Paul Spriggs and I, having folded a year or two ago to the pressure of our friends, are writing this comprehensive crevice garden book. Not shockingly, I have been too comprehensive at times.
Recently, I pared down the maintenance chapter from an over-thorough very rough thing I wrote a year ago or more. It doesn't fit with the new structure of our book, and hadn't had input from Paul, yet
Just for fun, I'm sharing it, because it may have details and nonsense in it that is amusing and useful to beginners and experts, or worth sharing with someone with an obscure google search, but not worth weighing down the paper in a book.
It's divided into sections, so you can skip parts (if not all!) and read about bits that interest you.
Most portions of this were scrapped and a few might just make it to the last cut.
How Crevice Garden Maintenance differs
Life is short- so crevice gardening had better be pleasurable, especially if you go through the great effort to create such a garden. This is how crevice gardens are unique; they tend to require more up-front effort: blood, sweat, tears, (and perhaps cash!), but require much lighter upkeep. It’s truly ironic. It is also truly satisfying that the dramatic boldness and proportions of stone still deliver their powerful impression forever after- while the greatest manual labor on a regular basis may be pulling tiny weeds and pruning tiny trees. Not wheelbarrows of clipping, but handfuls. Perhaps the greater effort of front-end good planning is in direct proportion to the ease of back-end aftercare. Don’t worry- you can’t prevent all the work- No matter how clever you are or successful a control freak you may be, nature will still provide you enough curve-balls to keep you on your toes and not taking for granted the well-earned and gentle appearance of the actors in your well-orchestrated flower ballet.
Most plant collectors, and crevice gardening seems to attract a disproportionate share of such folks- experience a storyline in their gardening life: they find an interest in a plant, acquire it, and then try to figure out how to keep it alive. This is the order of the the emotional motivation, and we fully defend the sacredness of that. But a cunning gardener who has certainly been through this cycle before, but is about to embark on crevice gardening- or even just create any new garden or any kind- can reverse the script and find the story works backwards very nicely, but this time, to the the great advantage of the gardener in ease of flow, with less struggle and failure. Here’s what we mean: Think of a new garden from the last thing you’ll do to it- the maintenance- and work backward. Design your space around how you want to interact with it, and then chose the materials, plants, and layout that prompt that interaction, because after all- that is how you will end up spending most of your time with that new garden. Truly, attitude or mood is the only difference between “maintenance” and “gardening!” So why not make it fun?
Why are crevice gardens easier to maintain? The stars of the crevice garden- cushions, buns, and evergreens- tend not to produce as much herbaceous material which needs cleaning up. They just grow slowly larger every year, and what little dead material does need cleaning is small in stature. The the crevice garden, there is also less room for weeds- the surface is almost entirely occupied by plants or rocks, leaving less room for uninvited guests. There is also the health benefit of the magical effect of crevices themselves- creating a better environment for the plants’ tops and bottoms. Pests are fewer; perhaps because their growth is less lush and therefore less attractive to more common pests, or the plants are from places where their enemies have not totally followed them; this depends on the type of crevice garden and plant, of course. It may also be, in part, because stones create homes for beneficial creatures like bug-eating lizards, spiders, centipedes, and others that go bump in the night.
But wait...There’s more!: Long-lived plants need replacing less often. The lean soils of crevice gardens invited fewer weeds, pathogens, and overgrowth. Fertilizing, pivotal in other gardens, is optional, usually used in only specific situations for the rock garden.
Perhaps another thing lent by the nature of folks who are attracted to crevice gardens is growing their own plants- their motivations may be of collectorship and interest in variety, or the challenge of that, because crevice garden plants are rarely something you can just pick up at a garden center. So, we like to think that growing and planting new plants, which isn’t usually in the garden itself, as part of the culture.
Lastly, rocks don’t die. Well, not really. A few kinds may decompose, but they don’t come and go like the living green stuff around them. Even if you find a way to kill off all the plants in your crevice garden, you will still find yourself with a sculpture of charismatic beauty which shines stoically like the naked rock faces of mountains. All of the traditional chores of gardening are eliminated, made optional, or shrunk. And you are about to take advantage of that like a wizard because you are reading a book about it.
A crevice garden begs a few special tools, or a special use of familiar ones. The small nature of the plants and the oddly rocky nature of the surface where plants live exclude old standbys like a good old fashioned spade shovel or hard rake. Most folks with a new crevice garden are at first turned off by needing to use new tools, but quickly become amused connoisseurs of devising their own or mail-ordering exotic tools for those certain tasks they do a lot of. Truthfully, it is a small adaptation and does not require an annex to the tool shed; crevice gardening is not a hobby like yachting, with the expensive barrier-to-entry of costly accoutrements; in fact, its home-made historical origins anchor it down quite earthily- any very specific needs can be addressed either freely or cheaply.
Tools are the route between you and your garden; so everyone finds their own course of smoothest sailing. You may be a tool collecting aficionado who takes pleasure in washing them after every use, or the gritty minimalist who stashes a couple trusty rusty utensils under a certain rock, a creative mind will make tools a pleasure rather than an encumbrance.
McGeyver’s stash in the Crevice Garden:
A butter knife and a half dozen coin envelopes. You might be surprised to find that Kenton, who maintains several gardens in different towns while he passes through, keeps just these two tools hidden away near his crevice gardens for impromptu visits and light maintenance. The butter knives allow for a swift prophylactic execution of young weeds before they become larger, harder, and time-consuming for the next visit. Paper coin envelopes, often the size of a credit card, can be kept dry in a plastic baggie, poised to be ready to help the visitor collect seeds which are suddenly or unpredictably ripe. These can be shared on the spot with flower-amorous garden tourists in the very moment because the paper breathes to dry the wet, fresh seed.
The average garden trowel varies considerably. What a crevice garden simply begs of one is to be stronger and narrower, as it must not only fit between the stone but be strong enough to survive literally working between a rock and a hard place- leveraging a trowel against a stone is harder wear on the tool than levering it against soil, and lightweight cheap trowels often snap at their stem or connection to the blade. Since rock gardens are nothing new, european-made “Rockery Trowels” are available and are exactly what they sound like: long, skinny trowels of hard steel that are of varying curve in cross-section. Hard plastic trowels exist, and their advantage can be one of comfort for the user, absorbing some of the shock of running into rocks, but we also find them useful working around bulbs and tree roots we don’t want to damage since they are less apt to slice into those subterranean bystanders. Take your pick of stainless or old fashioned metals, and rubber, metal, plastic or wood handles. Wood is not as cold to the touch in chilly weather and like anything wood, enjoys a bit of oiling/preserving from year to year if you like to spoil yours tools. Modifications and accessories maybe a holster to keep your hands free when the the trowel is not in use, or painting your smaller hand-tools some excellent gaudy color to make them easy to find when misplaced during a blissfully distracted day in the rock garden.
This is a special trowel, and is often the crevice gardener’s choice because of its slimness. Originally used by the dutch and english for sowing, transplanting seedlings, or planting small bulbs (since it digs a narrow, deep hole), its curved cross-section of the blade allows it to actually remove material from a narrow hole, which is harder to do with a flat trowel or knife which, in turn are easier than the widger to stick in the narrowest crevices. There are blade-only or handle-attached versions, and we’ve seen Do-it-yourselfers slice a PVC pipe lengthwise to create a plastic-blade version. Its disadvantage is that most makes are made of softer metal and can bend or snap off with long use. While it may have a blunt tip, I don’t recommend accidentally trying to take it on a plane.
Hori Hori/ Japanese Gardening Knife
There is lore that the gardeners of Japanese Emperors were the secret first defense against royal invasion before enemies even reached the buildings. It’s easy to pretend you are a royal guard with your Hori-hori in hand. These rugged suckers are what you most often see hanging from the belt of folks who work at botanic gardens, and for a reason. There are different styles of this dangerous looking tool, but the blades tend to be flat or close to flat (only slightly concave on one side), and one edge tends to be serrated and the other is sharp-edged, the tip pointed. The handles tend to be compressed (wider than thick- not round in cross-section) which is easier to hold and leverage. Blades can be all kinds of metal or even other materials, as with the handles.
Versatility is the top of several reasons this is most gardener’s personal favorite tool, even outside of crevice gardeners: the flat blade makes for good access in narrow places, the broad handle and heavy metal gives a person durable leverage, and the serrated side allows for cutting of roots or even pruning back of leafy material, almost replacing your pruners. A variety of materials, colors, and sizes are available now as their popularity has expanded around the world. Most include a measuring-marks on the blade so you can measure planting depth, but none of them are wifi enabled yet. Thank goodness.
This is not a funny brand name of some new trademarked garden tool. It is a butterknife, and unless you want to retire your current table set to the garden, second hand and thrift stores are a great source of them for mere pennies for the orphans of someone else’s set. They make a formidable and often perfectly sized trowel, are often stainless, and small enough a that they can be stashed, hidden, around the crevice garden for your unplanned spontaneous assassinations of weeds. They provide the narrowest reach into the tightest crevices.
Salad Tongs, Chopsticks, and other Strangeness
Desert and Steppe gardeners are not surprised by tongs- for that is the preferred way to handle spiny cacti, succulents, and thorny shrublets. Perhaps alpine gardeners will adopt them for their Acatholimons. Larger barbeque tongs are great for pruning and planting larger cacti. Don’t fail to consider the king of quirky cross-discipline garden tools: a locking hemistat meant for horse surgery. All of these gripping tools put some space between the gardener and many species of cacti which have glochids: minute, nearly invisible, and perversely itchy spines often hidden below the obvious ones. Since glochids can embed and ruin a pair of gloves, many cactus collectors do not wear them, but favor of a set of cartoonishly surgical tongs.
A few gardeners use skewers, tweezers, forceps, and even chopsticks to deliver the deep roots of young plants into tight crevices. Don’t balk until you’ve tried it. You may find it another excuse to order chinese take-out!
Your classic favorite pruners still find use in the Crevice Garden, especially among most fibrous or woodier plants pruned, but diminutive plants like Draba inspire many to use scissors or floral snips for finer deadheading. It is amazing how many gardeners use dull pruners. It is also amazing how many years religious believers in sharpening suffered dull blades before they learned. But once you learn the very easy skill of sharpening with a simple file, you’ll never go back. Sharp and oiled pruners not only help make the work easier on the hands and wrists, but makes the task fun and fast, as well as benefits to the plants with cleaner and therefore healthier cuts. Gardeners who collect many related plants- like of a genus, are more apt to need to sterilize their pruners as they make cuts between plants to prevent bacteria, fungi, and even crawling parasites from transferring. We’ve seen folks carry lighters, sprayers of rubbing alcohol (isopropyl) and even aerosol air freshener/disinfectant. Bulbs are particularly susceptible to virus transferred with dirty blades, and these are very sad friends indeed to lose because of spreading disease yourself.
Again, because of the smaller nature of the crevice garden world, as well as the narrow folds and valleys between rocks, a small hand-held rake works well in these smaller spaces. The material of the rake’s tines is worth thinking about, as there is a danger of damaging your plant’s tender leaves: metal will last longer, but plastic and wood (or bamboo) is less apt to scratch. Succulents are particularly susceptible to rake scuffs, so a good old fashioned broom may be the best leaf litter remover for them, even if being seen brooming off your tiny yard-mountain confirms all your neighbor’s suspicions about you.
Trenching Shovel and Sharp-shooter
They are certainly more used in construction of a crevice garden, but the occasional woody planting, removal, or perhaps rock adjustment or annex will call for this long-handled but narrow-bladed shovel. Small but effective, you will see why pipe layers are religious fans of this tool. Similarly, the sharp-shooter, which is the one with a short handle with a perpendicular grip on the upper end, is unbeatable working in tight spaces where the full power and size of a shovel is needed. That gripping handle allows you to twist the blade of the shovel, which is extra convenient for maneuvering around.
Even gardeners like myself who despise the irritating ever-present buzz of power yard equipment- we can be caught smiling warmly, and cooing gently to our leaf blower as we carry it out to clean fall leaves from the rock garden. Speed of air, distance from the garden surface, and direction are all part of the easily learned art of using one. You’ll find the sweet spot of speed which will remove debris but not scatter gravel. While you may kill the peace for a moment, it is unsurprising leagues faster than gently hand-raking fallen leaves around your precious cushions or picking up leaves by hand. It will not harm your cushions and bun plants which come from windier places anyhow; they may even like it! If it has a gas engine, don’t forget to maintain it as you would any small engine- a bottle of that fancy stabilized gas beats having to overhaul a clogged engine after the winter. Please protect your ability to enjoy the quiet for the rest of you time by wearing earplugs when you use one.
A reversible outdoor vacuum also works, if a bit less powerful. A clever gardener may even just use the utility vacuum to take up dead leaves, which is indeed smart, but takes special practice not to suck up gravel and soil as well! But beware, the above power tools can be surprisingly adept at separating your plants from their labels!
Yes, you need a camera. If the purpose of a crevice garden is enjoying it, then a camera not only preserves moments of joy- like the delicate glorious first blooming of a beloved plant- but it will cause you to take a closer look, to see the garden from new angles, and perhaps notice small details, which might well even be very practical- like pests or other new developments. A camera also helps as a record keeper. Photographs can be named, and visual plant maps can serve you well when the label gets blown away by the leaf blower!
Paper Bags and Envelopes
It’s wise to think of these things ahead of time, because we often discover something is in seed when we are not planning for it. Even if you are the rare crevice gardener who has no interest in growing plants from seed yourself, don’t forget your neighbors and friends who do, or seed exchanges, which are worthy and important programs to contribute to. Paper allows the bit of moisture left in aging seed-stems and pods to escape and allow the seed to dry safely. Just a few plant groups are best collected and maintained moist- like Ranunculus, so plastic would be preferable then. So often, the person who has the seed of a cool plant does so not because she was the only person who saw the plant in a garden or at the roadside, but because she was the only one with bags or envelopes on hand!
Why write about such a mundane thing? To point out that in comparison to the herbaceous border garden, where you may prune piles of plant material, collected into a wheelbarrow parked in the path, the crevice garden’s plants produce smaller amounts of waste which are easier collected in buckets, which can be carried over the rock garden easier than trying to off-road an oversized wheelbarrow. We find ourselves carrying a couple of buckets through the crevice garden when planting: one to collect or wash potting soil cleaned from roots, and one full of clean water to settle new plants in. Variations are your choice and comfort. For the industrious no-waste gardener, many sizes of buckets (in which foods were shipped) are often available from restaurants and grocery stores. Note that plastic handles often weaken from the sun’s light, and you don’t want to discover this if you use such a bucket to carry sloppy compost down your stairs out to the garden; you may be acquiring a new bucket that the carpet cleaner came in.
Plant Labels/Tags and Writing Instruments
The unique creative nature of gardeners blossoms here. Everyone has their own system and materials to fit their needs. Just take note of how a tag or marking material ages: wood will rot, plastic breaks down in the sun, some metals rust. It’s always that very beloved ancient plant, which has been thriving for decades, that you want to identify. You forgot- it was decades ago, right? Permanent markers may prove not-so-permanent with a little exposure. Burying a penned plastic label will reduce this danger. Embossed metal tags are a favorite of European plant collectors since there is no ink or dye to fade or wash away. Pencil graphite, (6B is best) being a mineral, does not decompose, but can be effectively erased or abraded by the movement of soil around the tag or like one of the authors, who repeatedly pulls them in and out trying to memorize the names!
Irrigation: Mention that one of the principles of crevice gardening is to not have to water too much - covered mostly in “principles” chapter but worth a mention at the beginning of this section)
Control over delivering water to cultivated plants is a key part of humanity’s rise to agriculture and civilization. We’ve been doing it in an effort to close a gap between what a plant wants and what the local climate has given it. It’s essentially artificial rain, so we can irrigate to create unusually ideal plant conditions- we basically create implied miniature rainstorms into the tiny world that is a potted plant.
In the crevice garden- the mimicry of rain is essential, since the path of water is a major part of the magic function of the crevice. Water drains over the surface of stones, concentrated into the lower crevices and sent immediately into the soil, pulling behind it oxygenated air. A crevice garden is different in that it does retain moisture deeply- water is forced to depth by simply being displaced by rocks, so surface drying from sun, wind, and warmth are all greatly diminished. And it does work best with overhead waterings. The water will run quickly off of steep surfaces to accumulate in basins and level areas, and that is just what it is meant to do. The movement of water from high places to low is simply how moisture microclimates happen in crevice gardens- the tops of mounds will be dryer and the lower edges will be wetter, and plants, sited accordingly, will prosper. Soils which remain moist can also tend to cool, adding temperature to the microclimate difference.
How much, how often, and when to water are all a matter of what you are trying to grow and where. There are no formulas, but we’ll give examples for reference. The closer the plant’s native climate to your own, the less intervention is needed from you. And it’s up to you to figure out the difference. You are not trying to exactly administer the same number of annual millimeters of water which fall on a certain plant in it’s native home, but approximate the effect of the whole environment of the plant. Crevice gardens are not just serving the needs of each plant, they are made to recreate a climate, so we learn to water the soil, and not just the plant. A person will learn to know when the soil dries out by poking into it or reading the plants.
An alpine crevice garden in a warm, dry continental valley may be watered as much as 1-3 times a week, (which is still generally less than turf grass lawn in those areas) while the same kind of garden in a coastal climate may receive irrigation just a few times during a dry summer. Again, how you water will be determined by your plants, your climate, and your soil. Like any garden.
Taking this basic need of plants upon yourself, at the cost of time spent (is it a cost to you, or a pleasure?) is the most sensitive, least water-wasteful, and most responsive to seasonal and weather changes- as well spot-watering new plants which may need additional water for a time. It forces you to visit the garden, the whole thing, regularly and intimately, which is at once pleasurable (maybe even meditative) and practical- by drawing your attention to things- like new flower buds or pests.
A big thing to keep in mind with hand watering is paying attention to how much water you are actually delivering, and fancy hose-end trigger space-gun style sprinklers are often to blame. Comparing the speed such a sprinkler fills a bucket compared to an open hose is one way to audit it, or by conducting a precipitation test by placing a cup or rain gauge out in the garden when you water (try to forget it’s there, ok?) and then see how much you are really delivering. It may surprise you. Also- don’t be afraid to poke into the soil and find out what it looks like, but know that a crevice garden is designed to be dry on top, so sending a wooden skewer deep into a crevice, letting it sit for a few seconds, then pulling it out, will reveal the deeper moisture by wetting that skewer. Or not.
We like to recommend hand-watering for new plants and small gardens. Plenty of folks have an irrigation system that they can turn on so that this task of making rain is optional- and not a chore, or that they only use when on holiday.
Automated watering has basically become so advanced and widespread, it’s like a religion; many folks just assume they need it because everyone else does. But irrigations systems are tools like any other- and a hammer can drive a nail as well as smash a finger!
A system is best used when irrigation is frequent and necessary. If your climate is moist most of the time, hand watering for that rare dry month is for you. But if you are a lowland continental gardener growing alpine which need water twice per week, an irrigation system will keep you from being a slave shackled by the hose.
Prefer overhead irrigations. Impact heads, pop-ups, rotators, and a growing circus of them exist to choose from. Overhead mimics rain the best, and is less apt to be intercepted by the height of the garden- something to bear in mind when making a system for a crevice garden: will the rocks and topography block water? Or can you use that to your advantage and enjoy a fake rain shadow for Dionysia? And, unless you are deliberately creating irrigation rain-shadows, it’s standard practice, for best coverage, for sprinkler head to be head- to- head, meaning one head can wet the nearest one to it; their patterns overlapping one another.
Also in the spirit of breaking rules- a few crevice gardens do employ buried or internal irrigation. It can be drip tubes and emitters or a perforated pipe, charging the inside of the garden with water, where the roots are, and allowing the top to be as dry as what rain allows. One possible downside to this is clogging of the system- you don’t want to go ripping up the garden to fix it.
The best thing about an irrigation system is how consistent it is. And the worst thing about an irrigation system is how consistent it is. You can use your buried system, but turn it on manually for a happy medium. While water needs may increase as the summer gets warmer, but most controlled systems continue to apply the same, making them potentially water-wasteful. Wet spots tend to invite weeds or moss or overgrowth, and only maintenance and vigilance can prevent this. The gardener, by avoiding hand-watering must now unclog heads, blow out pipes before freezes, replace broken heads, adjust heads, and adjust the timer, which may take less time, but more tools and skills.
One of the most unusual yet viable irrigations system styles is the temporary: spray-heads and tubes are set up, usually with a battery operated timer, and an area of all new plants is irrigated for its first season at somewhat wide intervals, like weekly or fortnightly, and it’s all removed in fall when the plants are well established and will be satisfied with natural precipitation from then on.
An irrigation system can make your life better if you know, most importantly, when to use one and when not to.
Gardeners in moist climates are not shocked by this, desert dwellers may cry blasphemy. A completely viable option is not to irrigate, at least, as maintenance. New plants usually need water to get started, (expand on establishing new plantings?) and of course raising young plants in containers or under shelter will require it.
The great advantages to not watering are first, obviously, escaping the task forever. Second, It does not provide excess resources to encourage weeds. Third, it saves water, which is important in arid zones where water is or will be a scarce resource. If you live in the desert and pay a premium for water, this one may top your own personal list. Fourthly, and this one is not to be forgotten- there is a special suite of cool plants which can only be grown very dry.
Gardening without irrigation is a bit different in that you are challenged to place plants in the water-microclimate that truly suits them, and that your establishment-watering must be successful enough that plants are able to grow on their own once you stop. A way of making this easier is picking a good time of year, like just before your usual cool or wet season.
The unwatered garden may seem limited by what plants can’t be grown, and it is, but this is true only to an extent. Relative wet microclimates exist even in unirrigated gardens- near down-spouts, at the bottom of a slope, et cetera. The unirrigated garden will tend to grow plants from the same or similar biome as where you live- including the overseas counterpart. Denver, Colorado, USA and Ankara Turkey are awfully similar. It is no wonder that plants from either place prosper in either place! The time you save from not watering may give you a chance to explore and discover all kinds of wonderful new plants from climates like yours.
The great bogeyman, the great monster, dracula, or just scapegoat. Weeds are an intrinsic part of gardening. It’s the logical balance to the concept of cultivation: Encouraging plants you like, and fighting plants you don’t. But weeds do not exist simply to annoy us, they tell stories about the place they grow and they are nature’s sincere effort to mend something which appears broken- disturbance to the soil or an empty ecological niche.
Generally, crevice gardens have fewer weeds because not only is the environment in the crevice garden different than that of the weed patches (and seed sources) nearby, but there is just less space. It’s been noted by generations of crevice gardeners that while many weeds are excluded, tap rooted weeds like the good old Dandelion- Taraxacum officinale, are right at home in crevices. Looking at their growth style, it’s no surprise.
A huge advantage in the war on weeds is knowing your weed. What is it? What encourages it? Is it annual or perennial? Know your enemy, and win the war!
Annual weeds must come in as fresh seed, so preventing their formation as far as possible is your first preventative move. But they are quick- so vigilance is needed. Most tend to be on a yearly cycle, appearing at a predictable time of year. This makes them easier to deal with. Don’t be too afraid of annual weeds, for they have no backup plan- no stored buds underground- when you pull them.
Perennial weeds are a different story. They do have a backup plan- maybe even an buried trust fund of energy to spring back with. If they spread by long rhizomes and are happy with the water regime or soil of your crevice garden, you should be concerned. They can weave between and just invisibly skip under your crevice garden’s stones, effectively avoiding the scorn of the weeding tool, and can come up to subsume your most precious gems. Be weary of nearby colonies of running grasses, field bindweed, bramble-like bushes, horsetail, nutsedge, and the like. Be concerned, but don’t cry- for there is always a way. The best method to win against creeping, perennial weeds is to eradicate them from the area before even building the garden. Your future self, committed to years of uphill battle, will thank you for it.
It may require thorough soil-screening, well-timed herbicide, and waiting for residual plants to try to come back in order to truly eradicate such a pest. Again, it is worth it.
The surprising appearance of a rhizomatous weed, if it’s roots and stems are indeed too deep to pull- can be treated by vigilant tireless pulling to starve the roots. It may take years and it may not succeed, depending on species. Or, they can be treated by painting-on an herbicide before their dormant season (when they are drawing nutrients, and therefore your poison, downward) and avoiding poisoning your nearby precious plants.
Herbicides, though easy to use, does risk poisoning your own plants or your soil, (or yourself accidentally) and since modern herbicides have not been around for a very long time, their true long-term effects on the soil and their chemical decay is not entirely known. Your own values and sensibilities will drive when and if you use chemicals, but they are still biotoxins, and personal protection when using them should never be forgotten.
There is much to be said for weeding by hand. It gets you into the garden and down at plant level. It’s meditative and teaches us humility. You can do it by hand and you can use tools. We are particular fans of hoes, especially hoop-hoes, for the large expanses of gravel around the crevice garden. You can pretend you are vacuuming them up without having to bend over or pick them all by hand. But even if you hate meditation, there are ways to avoid or reduce this task.
Avoiding Weeds by Design
Where you find yourself weeding is a great time to learn something. Why are there weeds here? Could I adjust a sprinkler and dry it out? Could I thicken the gravel so that the radicles of the weed seedlings can’t reach in and make it? How about planting a plant here to take up the water, soil, space, and sun? Who doesn’t want another plant?
If there is a place where weed seeds can come up in your garden, then it’s possible your own plants can reseed there, too. Watch closely and let the Draba seedling survive while you pull out all the weed seedlings around it. Designing a garden where seed germination is discouraged is great, and possible, but- oh no! What about your own seedlings? It will prevent them, too! Most folks find they have seed-friendly areas and seed-unfriendly ones, where planting grown plants is the only way to introduce new things to that area.
What kind of weeds you have can tell you a lot. Bindweed tends to appear when the soil is disturbed, dryish, and have improperly decomposed organics. Prostrate spurge shows up in compacted soils when the weather is warm. Most weeds show up when there is room to be a plant and no one is taking that spot! Just think- there is a reason why you don’t see weeds in certain place, like perhaps- on a mountaintop crevice! Let it be your game to create those reasons in your garden.
Generally, we find that a well designed crevice garden has less weeds as time goes on- the soil settles and the seed banks are depleted.
Just like irrigation, fertilizing is an artificial act trying to bridge a gap, to help plants which want more.
Every plant is unique in its fertility needs and tolerances. And again, like irrigation, it may be wise to grow your plants in zones where fertilizing is or isn’t going to happen. All plants are not created equal.
Fertilizing is often seen as unavoidable in containers, since the goal is to grow them up to plantable size, but their roots are limited in being able to seek out more food. In the garden? The soil, plants, and climate will dictate that. True rock-debris and crevice lovers often do not require much fertility. They may prefer the mineral nutrition in mineral soils with no organic matter. Others, like subalpine meadow plants, (especially Aquilegia) are hungry suckers who will gobble it up. Their native soils may actually be pretty rich in organic material. Lastly is how local climate affects nutrition. High precipitation means that soluble nutrients wash away, which would otherwise remain in the soil in a dryer place.
Practically speaking, chemical fertilizers are strong but short-lingering. They wash out as fast as they came in. Advantage or disadvantage- your call. Some may discourage soil life like mycorrhizae, which can be a good or bad thing depending on what you are trying to grow. Organic fertilizers are weak but long-lived and usually supply micronutrients well. Many nursery growers, understanding this, switch between or mix chemically- and organically-derived fertilizers.
Plants only take up fertilizer when they are actively metabolizing- weather by active growth or internal creation and storage of energy with mature leaves- so keep this in mind with your timing of applications. Over-fertilizing at its mildest means leafy, bloom-shy plants, and at its worst, means whitish leaf tips trying to sequester and shed salts (which is the form chemical fertilizers take) while the plant’s tissues effectively suffer from drought
Well fertilized plants provide better stem cuttings, seeds, and tend to overwinter better. Of course, plants growing in a good soil will also prosper here. Wouldn’t you rather have a full belly before you had kids or endured the cold? You may find you only fertilize your pots, the odd plant in the crevice garden which is not happy with the soil mix, or plants about to be propagated.
Remember again that the green things we are trying to grow in crevice gardens are often found, in nature, in pure rock. Do they really want the kind of feeding that woodland plants or vegetables need? Well, sometimes. But not often. They are still plants and may be opportunistic hogs, thriving on foods they’d not see in nature. But this may grow them “out of character,” and too much nitrogen can discourage blooming. There is also plenty of evidence that some plants are more apt to have diseases or rot when fed or overfed.
Just like not irrigating, your plant palette may seem limited by that choice, but the options open up for plants which prefer scant soils. The soil you have will need to have good mineral nutrition, at least, and they will grow slowly and steady, perhaps even living longer because they are “grown hard,” as the old phrase goes.
It falls from trees, it sheds from plants, it is the byproduct of living things being around. Where we are concerned with it in the rock garden is several fold. Most towns and cities are de-facto forests, so bringing a crevice garden into that matrix means it will have to be protected somehow from the implications of an artificial forest ecology. Especially if you are a neat-freak, you’ll think it looks bad- it doesn’t make sense with the mountaintop aesthetic of your crevice garden. Dead leaf material can smother or rot plants, since saxatile plants may not grow anywhere near trees in nature or the wind may blow away litter in their native home. Lastly- leaves decompose and create soil by becoming humates, which is lovely in the forest’s beautiful cycle of life and death, but isn't’ necessarily a welcome part of the scene for rocky places. Overly rich soil may mean water retention, and too much fertility, which welcomes weeds or upsets plants which love lean or mineral soils.
This is where the crevice gardener starts picking out the debris by hand, rake, or cracking out the blower. In fall, the gardener’s strategy for leaf cleanup in the crevice garden is often trying to nail that perfect target time when one, the offending tree has dropped all of its leaves but two- it has not rained yet and stuck all those leaves to the rocks and gravel!
The good news is that while an individual, deep, crevice may trap a leaf, steep slopes in the crevice garden can be used to discourage debris by simply shedding it off by gravity! A crevice garden can be designed so that basins or the flat areas nearby are allowed to receive and accumulate leaves, as part of the natural-cycle in a tiny ecology there with leaf-litter loving (woodland) plants, while preserving the mineral nature of the ecology in the crevice garden itself. It’s a small effort which does a big thing in the long term. You are acting as the great forces of nature which separate and define different ecologies. Smile to yourself that the simple act of taking crevice garden prunings and cutting them up to toss immediately as mulch onto a nearby herbaceous garden seems so lazy, yet is efficiently cunning, working with the tides of nature rather than fighting hard against them.
Trees- Neighbors of above and below.
We usually avoid mixing crevice gardens with trees because more often than not, they are at odds. Rocky places which inspire crevice gardens rarely have trees, so the plants of either of ecology find disagreement in the way they like to live. But this is not a rule, and what is more, most urban places where gardeners live are graced by munificent shade trees, and people must garden- acting as mediators- to keep these two in peaceful balance.
Trees cast shade, have roots, and shed dead material (leaves, needles, stems, flowers, bark, seed, fruit, whathaveyou), and all of these are mostly against the purpose of rock gardens and their plants- Most rock loving plants want sun, don’t compete with bigger plant roots well, and certainly don’t want to have junk burying or smothering them.
In dry climates, it is especially true that rock garden plants prefer sun, so shade will leave the plants stretched out, a bit thin, and certainly shy to flower. The roots of the tree will inevitably form a strong, dominating network, competing with rock garden plants for water in the soil. We find that in dry climates, a crevice garden under a tree may seem to need twice as much water (or, effectively, receive half) when under a tree. This will happen in relation to when the tree is active- a deciduous one, for instance, suddenly will not dry the soil when it doesn’t have leaves!
Trees as friends
You probably noticed there is an exception or reason to break every rule of crevice gardening.
In a hot climate, some shade will help cool alpines, perhaps a welcome service at the cost of having to clean up the leaves and water more to compensate for the tree’s uptake. In winter, the canopy of even naked deciduous tree branches actually provide a great deal of protection from temperature changes, and in the strangest way- by reflecting back part of the earth’s normal nighttime infrared heat loss.
We’ll also not forget that there are occasional rocky areas in forests which are essentially woodland crevice gardens, rich with ferns, trilliums, heuchera and bulbs, which although are in the forest, still benefit from being off the ground.
In a wet climate, a tree’s root system can create a welcome place for plants which want dryness- and conifers are especially famous for drying out the soil immediately under them. Falling organic material however, doesn’t have much of an up-side for crevice gardens.
Cutting Back Herbaceous plants
Distinguishing this from cutting away living material, we mean cutting back the yearly growth of of herbaceous plants, when they are in seed in summer, tired in fall, or totally trashed in spring and need removal to make room for the year’s replacement growth. This can also mean taking of the year’s dead flower stems which are above evergreen foliage- plain old dead-heading of lore. If you hate the practice of cutting back, then a Crevice garden is a fine thing for you, as it’s a garden where you can feasibly exclude all herbaceous plants and still have a stunning, lush garden. As we look at the spectrum of rock gardens going into crevice gardens, more cushions are common and fewer herbs (Here, we mean “herbs” to be herbaceous plants, which, botanically speaking, are any plant that does not overwinter its aboveground parts, dying to the ground every year). How many herbaceous plants (or “forbs,” too, as they are called in the ecology world) that you have in your garden is something to keep in mind when choosing plants if you’re the maintenance-conscious gardener.
In nature, herbs are not cut back with pruners, but sometimes by animals, by snow, fire, wind, or even flowing water. Within the bounds of being a garden, we humans take on that role, having kept the wildfires and flash floods out of our garden! In a crevice garden, removing last season’s dead stuff is not just a matter of aesthetic cleanliness, perhaps honoring the clean natural aesthetic of rocky ecologies, but also practical. The dead stems of an herb may smother a nearby cushion and rot it quickly. This is a real and quick danger, as the tightest cushion and bun plants generally do not content with litter in nature either by weather than blows it away or no shedding plants nearby at all. Like leaf litter cleanup, cutting back reduces decomposing organic material from entering the soil and enriching it, which the rock gardener may want to balance or control. Of course, if you are aiming for a wilder garden in the fast lane to entropy and want some areas to become richer and some leaner, it is totally legitimate to break this rule of cleanliness and let natural soils form in your garden. Although this may cause the tight-bootlaced gardener to blush, there is a growing school of horticulture and matrix gardening which is exploring this concept. Generally speaking, the artificial ecology of a crevice garden is trying to reproduce an environment where dead material is not wanted. The permaculture gardener may take those trimmings from the rock garden and cut them to pieces to be used as mulch in the herbaceous or shrub beds.
Another less rebellious reason to not cut back is to wait until the right time. Many herbs’ standing and attached dead material provides winter bird food, nesting material, winter interest in seeds/stems, and even protection of the plant through winter. Don’t underestimate the amount of cold protection that a bit of dead stems can provide to the sleeping plant crown at soil level- it’s significant. This is most useful in dry and cold winter climates like Colorado, USA, where there may or may not be snow cover. We can enjoy the stem forms all winter to consolidate cleanup down to once in the early spring- which is a pleasant time to be in the garden, stretching winter atrophied muscles and enjoying the earliest blooms.
In mediterranean or other winter-wet climates where rain is more common than snow, that same dead material may start rotting immediately in winter and pose more imminent threat to plants, and may be best removed before winter. Or, if you just like a cleaner look with no dead material during the winter, suit yourself to late fall cutting back.
Another great time to cut an herb back is when you collect seed, usually in mid summer. If your plant is the type to essentially exhaust itself and its good looks with seeds, like Oreganum, Alyssum, Calylophus, tall Penstemon, XXXX(ADD SOME, PAUL!), they can be cut back to green growth or strong buds, which may even mean to the ground, which often results in the formation of a new, clean little flush of leaves before fall.
In the case of evergreens and some small woodies, which have annual flower stems which sit on top of permanent leaf stems, like Moltkia petrea, Lavander, and Aethionema it is convenient to slice off the dead stems where they meet the living plant, as it’s a distinct line. This is also true of any tall-stemmed buns and cushions like many Acantholimon, Hymenoxys acaulis, Eriogonum (ie umbellatum), Andryala aghardiana, Limonium minutum. You can gather the stems in a fist and cut with the other hand. When the plant is firm enough and the stems brittle enough, it may only take rubbing your hand over the top of the plant to knock off the spent inflorescences. This is very satisfying, but wear gloves if you are going to do that to Acantholimons! Some folks use an outdoor vacuum for this because they can take up the shattered small pieces of stem.
Finally, there is cutting back to control. Some herbaceous plants or small subshrubs might be getting out of hand or worse- covering neighboring plants- like Scuttellaria orientalis, Helianthemum spp, Veronica liwanensis, and Aubretia, they generally be safely cut back after flowering or in spring when they are starting growth. Many respond more favorably to being decapitated to the ground than you would expect.
Grasses in the rock garden will fall into the two grass categories- warm and cool season. There are few warm season grasses and sedges used in crevice gardens,- expect that to change in future thanks to arid climate gardeners- but those like Muhlenbergia, Bouteloua, and some Stipa can be cut absolutely to the ground in fall or spring to make room for new growth. Cool season grasses and sedges are more common because there are small species available, like Festuca spp, Poa spp, and Carex appalachica. Since they keep many or most leaves over winter, they can be cleaned out by rubbing a hand though them, raking, petting or a gentle grabbing motion to try to remove the dead leaves which are intermixed with the living. They will grow right back if you get tired of that tediousness and just shear them all the way down; they will just think they were grazed by a mountain goat. They evolved for that.
Lastly, the cushions and buns. These are the plants most unique to crevice gardens, and their cleaning is different. Standing flowers, as mentioned above, are easy to remove. Very easy, in that “Why didn’t I start crevice gardening earlier?” way. Then there are the sessile flowers (those without stems, embedded directly in the bun of the plant), like Silene acaulis, most do not have anything visible dead after they finish blooming, others have tiny bracts, calyxes, or dried up petals peppered across the bun. These can be rubbed off gently with a hand or broomed off. Buns have a tendency to die off in sections as they age or live out their generally long lives. This is obvious when a section of a bun goes brown. This can be tweezered out or plucked out by hand. Some gardeners fill the void with gravel or stones to keep the tight form of the rest of the plant.
If you are lucky enough that a bun, which tends to be a valuable slow-growing plant, is actually getting too big (perhaps it is about to swallow another, more valuable plant nearby) they can be pruned. If flexible, , like most Acantholimon, Antennaria, Thymus, Eriogonum kennedyi , their edges may be gently lifted, so pruners can slice through them like scissors taking off the corner of a sheet of paper. If it is a firn bun with an inflexible deathgrip to the rocks or earth below, like Arenaria alfacariensis, Saxifraga cochlearis, Gypsophila aretioides or Minuartia stellata , it may take a knife or blade-side of the pruner, diving in from above and at an angle pointing into the ground toward the center of the plant, cutting underneath a little, so that living rosettes are left at the very edge of the plant rather than beheaded stems ending at the cut. If you are wise, you will time your bun pruning with a good time to take cuttings of the plant!
Pruning, Reducing, and Training
Controlling woodies in the crevice garden is no different than woodies in the rest of your landscape, except that they are probably extra-miniature.
When faced with the promise of being able to collect lots of diverse woodies in a small space, most of us will find that even miniature conifers and other trees, although still knee-high, are pushing their bounds in the crevice garden. Because their branches are tighter and closer together, dwarf trees are more difficult to see to know where to cut and make reductions. Many conifer collectors “candle” their Pines, spruce, and fir- which is simply snapping or cutting off part or all of young new stem growth in the “candle” phase- before the needles have grown out. This can be done to shape and contain conifers yet more than their genes allow.
Miniature woodies should be pruned at the same recommended time of their full-size relatives. Deciduous trees will be easier to see without their leaves, so early spring is best for pruning them. Some daphnes, (Which sp?) which have latent buds at soil level can actually but cut completely down to re-grow. It may be hard to do if you’ve waited twenty years for it to reach that size, but its return, this time with a great root system, will be faster and just think of all those cuttings!
Otherwise, the rules of pruning evergreens- be they Daphne, conifer, Heather family members, are the same as when they occur in the greater landscape. Why it may be different in the crevice garden is why they need pruning- usually it is not out of height, but width, where they begin to shade out other desirables, so most rock garden woodies find themselves being reduced laterally more than vertically. In this case, those widest-reaching stems can be held to be separated from the rest of the plant and cut at their base where they issue from an older stem. This also gives you a chance to see what the plant will look like missing that branch before you commit to chopping it.
While woodies can sheared to change their form, simply cutting part of them off as you would a hedger, like a knife taking the edge off of butter- the plants will benefit from thinning, too, if they are older or becoming too thick, and running out of room for new growth. Woodies can be thinned by simply removing stems throughout their form, so that little gaps are left here and there to allow nearby branches to fill in. This is usually most useful in the case of older plants, or ones not getting enough air movement or drying to their interior.
Finally, we’ll talk about training woodies. No fetching or rolling over, but sending them one direction or another, or lifting their branches away from the rocks so that the stone can be seen or there is room for other plants at their feet. Often, a woody plant living on one side of the crevice garden can be trained to lean away from the middle of the crevice garden, leaving that sunny, rocky real estate for other valuable plants, while they occupy their area hanging over the edge. Training is best done early, as a branch is better to cut when it is a few centimeters long rather than a meter. This can be done to keep woodies narrower, so that their footprint or shadow is reduced, but they are allowed to grow taller.
Some gardeners will like to “limb up” some of their trees or shrubs so that their trunks are visible, especially if they have nice peeling bark or special curvy form. This is good to increase air movement within the plant in moist climates, but it also allows semi-shade tolerant shorter plants to grow underneath the canopy, and maybe even hug the trunk.
But “limbing up” (crown raising - as the arborists call it) is not always the way. Sometimes there is nothing more artificial looking than tiny trees with tiny trunks which look like model train layout decorations, mere gremlin versions of street-side trees which have been pruned up so that humans and lawnmowers can pass below them. If we take our inspiration from nature, we’ll see that a great deal of conifers, especially those found intermittently in rocky places and alpine, have branches, like a flowing dress, completely to the ground. That interaction between the form of the plant and the three-dimensional rocks at its base, where a branch may embrace the sharp edge of a stone- is one of the charismatic reasons for inviting tiny trees into our rock gardens. At the end of the day, it is a matter of opinion.
It’s important that while we take the referee’s role of keeping the order in the crevice garden, we let the plants be themselves. A skilled pruner can maintain all of his plants in such a way that it is not obvious he has been doing it. He will reduce size but preserve character. Perhaps because of the tight-form and open-space nature of crevice gardeners, the most well-designed garden will need little, if any, size-reduction pruning at all.
A Four-Season Look at keeping the Crevice Garden
We will assume you have a big crevice garden with all walks of plants, and have a combination of every climate so we can address the basic yearly routine below.
Get out there and enjoy it. No one has to tell you because you were probably stuck indoors all winter waiting for the temperature to warm while you looked at seed catalogues and imagined those plants in your garden. Deaths from the winter will need to be cleaned up (don’t let the evidence distract you from the bliss of spring!), any residual leaf or litter debris can be cleaned up. Overwintered new plants can be planted, and lists or maps of the plants can be updated for the year if you are that type.
Winter annual weeds, like Dandelions, having germinated in fall or winter or just days ago are begging to be demolished before they can mature to drop their own seed. Summer-blooming herbaceous plants, just emerging, are best dug transplanted or divided (or taken as cuttings for propagation) now before they get too big. Early flowering perennials should be split in late winter, and snowdrops can be moved or divided “in the green” when leafy but done blooming. Fall Cyclamen seed is about to mature and you’ve had all winter to forget they are there, coiled up under leaves on the soil.
Woodies get any pruning they need now, just at or before leaf emergence, while their sap flows to heal and clean cuts. Any warm-season perennials or grasses whose dead stems and leaves you left through winter are about to emerge or are just doing so, so it’s time to clean them up- a yearly task that perhaps creates the most profound and satisfying impact when you stand back and look at your work.
If you grow your own plants and have winter-sown seeds, keep checking on them frequently in case they must be moved to a place to grow-on after they’ve germinated. Now is about the time they and the home nursery needs watering to keep the pots moist. If you cover any alpines with evergreen branches for winter wet/sun protection, these should be lifted in late winter to early spring just before they start growing lest they etiolate or rot. Similarly, winter-rain-blocking panels for your wet-winter british climates can be taken down and stored to let the plants receive spring rains and moisture.
In a similar vein, Spring is when residual winter moisture is running out in dry climates, so the irrigation system may be turned on, and it had better be tested and adjusted after its winter rest, as well as a fairly thorough hunt for new leaks from frozen pipes. In a hot-summer climate, Spring flowers may distract you dangerously to forget that the toughest part of the year for them is coming soon, when you must help them out with irrigation or shading in the case of gardens in greenhouses, frames, and containers. Don’t forget pots and containers that are sunk or plunged for overwintering- time to bring them out!
New appearances of pests begin in spring. Many kinds can be suppressed before their populations increase- so early detection is the way. And since the plants are also starting their activity, now is the time for your first fertilizing if you do that.
Lastly, any damage done to a new crevice garden by frost heaving can be dealt with now- stones buried deeper, slopes and cliffs better footed to prevent it from happening next winter, and a fresh addition of gravel if soil was exposed in the process.
Things are greener, and bigger. Both the bloomed- out spring bulbs and herbaceous flowers who will need dead-heading (and their seeds collected! Some plants who have made and solidified their year’s growth already can be propagated by cuttings.
Warmth means that irrigation may need to be turned up, or deepened by longer duration. Since this is the time that vegetable gardeners are putting out their tomatoes your warm-season plants headed to the garden (like Yucca, Agave, Bouteloua, Salvia, Zauschneria, and Cacti) are plantable now, and while you do that, you’ll find nature’s warm season weeds, like knotweeds (Polygonum) and prostrate spurge (Chamaesyce humistrata) have also appeared!
Autumn is when the full grown size of plants is visible, and judgements about editing plants are easier to make. Cool season plants (most alpines) can be transplanted or divided or planted, in fact, in places where the hot summer is worse than the cold winter, fall is often better! A deep soaking of water will last into the winter just before irrigation lines are emptied and blown out to prevent freezing.
Tired- looking summer bloomers get chopped down, but architectural ones can be left for winter, you get to judge the difference. Make sure to collect seeds off of them to keep yourself busy in winter. Another group of plants is ripe for cuttings to be taken.
Looking forward to winter sun, you might place conifer boughs on burnable buns. Anticipating deep cold, movable containers get sunk in the veg garden, plunge, or overwintering frames. If you are in London looking to protect your cacti-studded crevice garden, you’ll put up the rain roof. Home nursery winterizing happens as a yearly dance watching weather and the sky.
Those perennial weeds with deep rhizomes a few paces away from the crevice which make you shudder at their invasive potential- they are best sprayed now, before they turn colors or dry up, so they draw the poison to their roots with their energy being stored for winter.
If you expect snow and you have seeds to direct-sow, put them down now so they are safely hidden from hungry birds by the snow.
Lastly, the leaf litter game begins for most folks who live near trees. We try to get the timing right after maximum fallen leaves and rain to make them adhere to the garden like wet confetti!
The form of the garden is what you get to enjoy most in winter, maybe as its features slowly disappears under a blanket of accumulating, ebbing snow. If that snow or normal winter rain does not come, it may be necessary to winter-water. This is more common in dry interior climates, where also a lack of normal snow cover can leave alpines to burn under the winter sun- common victims are small Dianthus and Acantholimon trojanum. If this danger appears, you can put down those conifer boughs or other breathable coverage. Or, you can take note of the suffering plant to transplant to a winter-shadowed area.
If the ground is not frozen in your region, winter is strange but fair game for transplanting, splitting, or planting new plants (as long as they are not warm-season, usually summer-bloomers which generally need to be well rooted before winter, so best messed with in spring). Think of it as rearranging their lives while they are asleep. Similarly, some plants, often cushions and broadleaf evergreens, can be cutting propagated in winter, and you have more free time to coddle them.
So many crevice garden projects for winter aren’t outside, which is conveniently closer to the teakettle and booze cabinet. Much of it is a juggle of seed: cleaning seeds, perhaps separating them to share with friends or store yourself, or winter sowing them into pots, which can be done inside dry.
Special Maintenance: Protections
Your design and your growing style will determine if you even need to consider protecting your plants from the extremes. The plants or beds of plants whose native homes are most different from your local climate will be the ones who need the most help, especially against the toughest times of year known in your climate. Every gardener figures out accidentally how much trouble they are willing to go on a regular basis to grow some kind of plant. As such, every style is seen, from intensive , constant work to maintain the right setting, to the laissez-faire style of creating the right passive microclimate up front, picking the plant for the place, and refusing to make a special effort to protect them from normal things that happen in your zone.
It’s a lot of work trying to protect plants from something they need and you have too much of, but alpines grown in a frame or greenhouse will need venting, shade, or probably both so they don’t cook, as high temperature tends to fall hand-in-hand with the sun. It comes with the greenhouse expectations. But what you may not expect is protection from winter sun- it’s most apt to happen with plants from snow or cloud- covered winters or places when grown in winter-sunny climates.
Plants in pots- be it a small trough that needs moving to the east patio before summer heat or your home nursery which either lives north of the house or under a shade-cloth; they need the shade as a result of being in pots and their limited water and higher temperatures in summer. Standard black pots, unfortunately really heat up the little roots and soil. Plants don’t grow in nature in pots, so they are pretty delicate when we coerce them into it!
Truly, good placement of your plants, troughs, pots, or nursery will solve the problem of sun on the design side.
If your normal rain is already too much for what you grow, time to exclude natural precipitation. Not at all new in alpine gardening, this is usually just called growing under glass- under protection, or under cover which may refer to growing in a greenhouse, which a person should realise excludes the rain so that the gardener has tyrannical control over all water.
Often used by alpine enthusiasts in winter-wet climates, there is an in-between approach to the greenhouse and the open garden for creating dryness: by erecting a shelter, perhaps temporary or mobile, to cover a section of outdoor garden. Some folks have a frame on which they can hang or remove glass or clear plastic when they need to, others have sunken poles or posts to which stakes are attached which support the overhang- the advantage of this is that this contraption can be removed when the weather is fine, you want the rain to water your garden, or you’re hosting a garden tour.
Snow and Hail
Snow is welcome to the majority of plants, but for woodies not structured to support it- they should be tied in twine, wrapped in burlap, or just not planted where the roof will shed exponentially on them! Generally, snow is a free blanket to keep your plants snug in winter, helping them avoid temperature fluxuations.
Looking at some historic glass greenhouses in Wyoming, USA with a friend years ago, I saw that all the houses were entirely covered with a superstructure of chicken-wire mesh with holes about 2.5 cm/1” wide. I asked if how such a wire shell could possible protect against hail that was smaller than the holes, and he said. “No, it’s for the hail that is bigger than than.” Most rock garden plants, especially alpines, and especially inland alpines, are completely evolved to be hail proof, or resilient to it. For a special collection of those that aren’t, you will be challenged to find a way to make wire mesh or wooden slats look pretty, since it’s usually impossible to accurately predict a bad hail event in time to go cover your leafies.
Yes, while most alpines are the world’s champs of cold survival, you are a gardener, never content, and you will find plants who are a few degrees short of naturally making your winter. If good microclimate placement isn’t enough, covering will be necessary. It’s worse in pots, since plant’s roots are, by nature, less hardy than their tops. You can help by sinking, or “plunging” them in the veg garden, soil, sand, or at least touching the earth; it’s a huge advantage. Otherwise, they can be covered with polyester frost cloth, a cold frame, dry leaves (if you can trust them to stay dry) or even conifer boughs. Oddly, overwintering plants in winter-shadowed areas helps by keeping them from temperature fluxuations which cause drying out, or waking untimely to freeze to death. Let them become ice cubes and stay that way.
You may find that those plants right on the edge of hardiness can be ignored except for that one nasty winter night you go out to cover it with a blanket, a upside-down styrofoam box, or a shovelful of extra snow.
That cleverest gardener, again, may never be caught mulching her mysteriously perennial tender african bulbs- because she does it growing them among grass tussocks which passively provide that protection!
It’s just like snow. You are silly for growing something that doesn’t like wind, or, silly for planting it in a windy spot. On the whole, rock garden plants get better- growing tighter and growing “in character” with what we’d prefer to call wind: “Good air movement!”
Hey, I thought we were done with heavy work already! Sometimes the garden needs a fresh topdressing, the original surface having been subsumed, rolled away, pooled in some places, or otherwise mysteriously disappeared. You may suspect the neighbor’s kids. Keeping the same variety or color of gravel uniform, as well as providing the different sizes, can be tricky because the produce of gravel pits change as they dig deeper and wider, so you’ll be wise to stockpile some at when you build the garden.
New gardens settle, most of it in the first year, so sunken pockets will need some filling to achieve their permanent level.
Spring is the easiest time to add any needed top-dressings of gravel, because herbaceous plants are at their smallest for the year and your always-tiny gems (including spring bulbs not visible in summer) are basically wearing their safety vests which beg you not to accidentally bury them: their bright flowers. You’ll notice that winter has the magical effect of settling gravel and chips in a relaxed and natural way, locking them nicely together, so enjoy that aid from the winter fairies. A splash of water will help start this and knock down the dust until they do their work.
Rich, organic pockets can either be top dressed with compost when it’s available, or with chopped-up clippings/leaves when they are at hand.
Plant Tracking Systems
Crevice Gardens are famous for the sheer number and variety of plants in them. Few things come closer to forcing the home gardener to start acting like botanical gardens staff.
Here is where your personality is betrayed. Neat-freaks will keep copious notes, trivia junkies will memorize every plant’s name, while relaxed pleasure seekers will not record anything at all. We’ve seen everything. Tags alone offer their own variety of styles, and list systems, too. A famous anecdote, which has been repeated often, goes that a neighbor once saw all the tiny tags in a rock garden and asked if it was a “mouse graveyard.”
Crevices themselves make quite the challenge in general, since there is less free ground to bury tags! Most folks slip them in with the trowel when the plant are planted- the tag in the same crevice. Here is a sampling of the most common and diverse strategies: Plastic tags, pencilled, buried (and therefore defended from the sun) just under the gravel to a consistent direction from their plant, like “the tag is always just north of the plant.” How about the tag hidden under the nearest lose stone? Or nails with enamel numbers painted on the head.
Embossed copper strips pinned down with a big staple to the ground in front of the plant- this is very permanent. Lastly, a recent one: A screw whose thread resists heaving out of the soil, whose color blends with the rocks, but is visible the gardener about to plant something new before he chops into dormant bulbs marked with that screw.
Some folks bypass tags entirely by keeping track with photos, binders, maps, and lists. These certainly prevent labels from cluttering the garden, but must be up to date or even present at all during the time that questions come to mind!
A list or map requires that different beds, slopes, aspects, and areas get names or numbers to use in conjunction with an actual list of plants, like a census of your own little insane kingdom. You’d be amazed how many famous rock gardeners accidentally refer to a certain berm they’ve internally named after a friend like “Mount Halda” or “Stireman Plateau…” An off-site list of plants is good for public gardens where tags and plant names are not important or are too frequently broken or stolen, which is particularly frustrating when some plants live, move, and die so quickly! A list must be updated when plants are planted, and can include as little or as much information as you want, for example: Genus, species, source, common name, color, expected height, date planted, number planted, size of pot, location in garden, and date dead. Just make copies or backup files in case you lose your precious history!
Just start by keeping your end in mind. Why and when and for whom do you want to know the names or histories of plants? And how easily will it be to maintain it? Remember, the most successful plants will grow up and swallow tags right next to them, and sadly, many plants lose their value to others if they lose their name or provenance.
Pests and Diseases.
Here is another chance, while going into great depth about maintenance, to tell you the advantage of Crevice Gardens. Generally, these plants have fewer attackers. It may be owed to their un-lush nature, the uninviting rocky environment to traditional pests, the excellent airflow and exposure working against disease, but admittedly, the few pests in the crevice garden may be pretty new to us, since there is not a long history of people growing tiny plants in heaps of rocks! Crevice gardeners, on the cutting edge of gardening, may find themselves being the practical solvers of their unique challenges.
The warm, dry, free-draining and mineral environment is an immediate discouragement for fungus and bacteria. The accumulation of dead organics will work against this- a motivation to keep the garden clean, but some buildup is unavoidable, and some fungal attacks will happen anyway because of climate stresses on the plant. Some appear slowly on the leaves, giving you time to treat it or for the weather to change and the plant to recover, while other diseases are strikingly immediate: especially among pioneer plant species which we’ve seen suddenly die, even while in full bloom.
Don’t underestimate a plant autopsy to determine what killed a plant, especially by just seeing if it was the leaves, crown, or roots which died first. Some immediate deaths can be easy pinned on root-eating creatures, like various species of insects’ larvae who has a non-discerning diet, as long as they can tolerate the gritty soil of the garden. You’ll enjoy learning what caused it as much as squishing it with your trowel. Admittedly, growing plants in
Insects like aphids, true bugs, grasshoppers, vegetarian beetles and the like, seem equally happy to eat healthy or sick plants. Make sure to try soapy water as a powerful bug scrambler, before you reach for more scary stuff, it seems most effective on anything with six legs, but not so much on molluscs and crustaceans…
Pillbugs, sowbugs and roly-polies. Some eat vegetable matter and some don’t. You won’t ask them who is who when you go stomping them in revenge. These chemical-resistant tiny tanks are best discouraged by cleaning up the leaf litter they hide under. The same can be said for earwigs, except that they are also affiliated with satan and soap-water does work against them.
Slugs are discouraged by the dry expanses of rock in crevice gardens, but are given free range in the coolness of night to mow down campanulas, especially. Since they are slow moving and reliably night active, manual murder patrol by the gardener is as popular as using slug bait.
It’s been said that when you take up crevice gardening, you trade away all of your old pest enemies for one: ants. This may be the most universal and uniquely crevice pest. That warm dryness and great drainage in the crevice garden you put together with plants in mind means you’ve also created the ideal, easy-digging living situation for ants; for the drainage is ideal for tunnelling, many species prefer open habitats, and the warm backs of rocks make ideal incubation chambers for their larvae.
These armies for the Queens of the underground usually have a most- active time in spring constructing new excavations which undermine stones and plants. Sometimes they will target plants in their way, other times they will simply remove all the soil from its roots or bury it. We’ve noticed that soil that ants have worked with intensively repels water, perhaps through the action of saliva meant to protect their homes. Whatever the case, it’s awfully annoying when water does not soak into your garden while the plants dry up.
Ant prevention can mean a little more water to areas where they are prone, bait or traps (to avoid poisoning other innocent beasts), or control of populations by soapy water floods to their entries. If you have room to allowing one part of the crevice garden to be a permanent ant colony, and they agree to this truce ot territory, allowing one population can fill the niche and prevent others from appearing.
One of our friends has a totally different response to ants: Birdwatching. A wildlife artist as well as crevice garden innovator, she allows the ant colonies to become Flicker feeding grounds so she can watch the birds lick up ants with their long tongues. She notes that the dirt excavated by the ants to the surface settles down and washes back under the stones and gravel on its own.
Beneficials on Plants
Remember that systemic pesticides essentially render the plant poisonous for a long time to all things which may interact with the plant, including bees, pollinators, and other beneficials. Contact pesticides, like pyrethrins, do not have the same prolonged dangers. Do not underestimate the role of beneficials in your garden until you have sat at ground level and watched all of the crawling and flying life for a day. John Stireman in Sandy, Utah, USA once said that “By paying attention to the insect life, you can essentially double your pleasure in the garden.”
Plants on Plants: Competition and Allelopathy
It’s truly hard to know when plant are actually competing, because you can’t see all of their roots to know where they are and if, for certain, that is the reason they are thriving or not. Simply keeping some plants from overtaking others, or moderating a balance is not just a job of the trowel, but of the hose and fertilizer- by encouraging or discouraging plants with the environment you create.
Most plants co-exist well, but there are those that don’t- beyond the big kid simply swamping the little kid. A few plants are allelopathic which means that they use underground chemical warfare against other plants, which can be their own species, to other species, or even just prevent germination of their own progeny! (Have you ever had a million little seedlings appear in your garden only after the single, original mother plant died?) It’s more common than we thought, the famous example being Black Walnut, Juglans nigra, but more discoveries are made every year. It’s complex, and it’s new, so the implications in crevice gardens are mostly yet to be seen, but we think gardeners should keep it in mind so that we learn from observation. Why care? You could find that you can use your favorite allelopathic plant to prevent weeds! It’s been done.
Even more mind-blowing is mycorrhizae, or root-associated bacteria. Many plants rely on it to help “extend” their roots to give them the nutrients they need, but others, have even more complex relationships, like XXX (the leafless orchids) which is a beautiful plant who is a parasite on the mycorrhizae which works for a tree. In its aid to one plant, it may be preventing or killing another plant. Scientific study of mycorrhiza is not particularly focused on alpines, so rock garden plants are deeper in the shroud of the undiscovered than many!
It would be sad to ignore one of our favorite, beautiful plant-attacking plants: Indian Paintbrush, or genus Castilleja. Most are hemi-parasites, deriving part of their energy via theft, and have been known to actually kill host plants in the crevice garden. Since they are so pretty, we’d just recommend finding them a tougher host!
The horticulture industry uses the term “integrated pest management” to use chemicals alongside or as a last-case scenario behind good management and protective practices, as so many troubles can be prevented by better care rather than their late symptoms treated. Where disease is concerned, a healthy plant has a better chance. Where insects are concerned, environment and housing can be changed even if you leave their food source- your plants.
Mammals may also work against you. Specific to crevice gardens may be voles, which have always been known to prefer making their burrows under the protection of stones. They are a rare pest of the crevice garden, and even rarer when you have a local hawk, cat, or fox population.
Dogs generally have less impact on crevice gardens than they do in normal gardens, chosing the paths of least resistance and walking around the mounds and stones. In fact, the presence of dogs can discourage rodents and small dogs with the need to sunbathe are useful in detecting the warm microclimates.
Rock heaps, and especially those looking like miniature mountains, will inevitably attract children. We have no advice for this, but only warnings. Little ones grow into big ones, and both will step on your plants. When asked “what is your worst pest in the garden?” without any hesitation, the great crevice pioneer Josef Halda replied: “People.”
Conclusion- Are you Having Fun?
Crevice garden maintenance is at once nuanced and engrossing, satisfying and frustrating, easy and difficult, or predictable and surprising, as traditional gardening, if not moreso. If it were easy, would we not be bored and move on to less easily conquered hobbies? If nothing ever happened to the rock garden and it remained the same all the time, would we ever think to look at it? You know you wouldn’t. A garden’s purpose is for you. To please, to challenge, to reward, and to humble.
You will make those little adjustments over the years lived in your crevice garden- changing the nature of it’s maintenance. You will match your desires with its potential. And you will know when big changes need making- are you happy in the rock garden? As we age with our gardens and our backs cannot take the weight of heavy lifting- our minds have grown sharper, and we’ve found a way to dance with our partner- only gentle, thoughtful adjustments are needed to keep the harmony.
Compared to the rich plethora of subsets of gardening, from espalier to bonsai to tropical orchids, we think that crevice gardens hold at once as much entertainment, amusement, and engagement, yet if you stop maintaining the modern crevice garden, the consequence would not be so immediately disastrous and final. They offer a long-form conversation with every aspect of backyard nature- weather, physics, chemistry, botany, and wildlife- all of which whisper the gentle companionship and solace of the mountains