Monday, August 22, 2022

Plants for the Unwatered Crevice

 Several friends' inquiries made me realize this was needed. So here it is. 

These are species I have grown without irrigation, in crevice. I am sure there are more. There are a few things that seem to require being in either/both crevice and unirrigated. 

Know that a "rock garden plant" is subjective, and usually comes down to size and habit being appropriate with your rocks. Plenty of these are too large for a small crevice garden with small rocks and are noted as such. As with any unirrigated garden, performance and show will vary with rain and weather year to year... just like nature. 

Keep in mind that different parts of a crevice garden receive/repel more or less runoff, so plants specific to those are noted. Soil type effects things, too. Generally silt and clay hold more water longer. Also know that all plants will need supplemental (at least weekly) irrigation the first season to get established. 

Also know that Bob Nold’s ‘High and Dry” is basically an encyclopedia of plants that can grow without irrigation in Denver (and this classic book has a rock garden plant chapter). We are a little more limited over here in the hotter/drier Grand Valley.

So here it is. 

If this is useful to you, I recommend saving it to your computer before practical blogs, like this one, get buried or are left unsupported.

Plants for the unirrigated crevice garden in Colorado. 

(below 6000’asl, like Grand Junction and Denver)

Flower power

Castilleja integra, sessiliflora. C. miniata in shade/wetter. 

Physaria ovatifolia, fendleri, arizonica, and most others but alpina.

Phlox nana (not a tiny plant, it creeps.)

Phlox hoodii (tiny)

Scutellaria resinosa (in a wetter spot, Denver not GJ, not tiny)

Melampodium leucanthum (not tiny)

Zinnia grandiflora (spreads a lot, large gardens only- it will eat your small CG for snack)

Arenaria desertorum hookeri (seems to like afternoon shade)

Astragalus utahensis (short lived with organics in soil)

Astragalus spp, so many other western ones.

Heuchera pulchella, abrahmsii, rubescens, even ‘Firefly’ (in deep shade and or with good runoff)

Ephedra minima/monosperma/regeliana in Denver, not GJ. Spreads by rhizome!

Liatris punctata- maybe too large for small gardens.

Phemeranthes (Talinum) brevifolium, parviflorum, calycinum, sediforme  (capricious, sometimes brief.)

Lewisia nevadense

Oenothera caespitosa (up to 1-2’, some forms are rhizomatous, most are short-lived)

Oenothera howardii (up to 1’ wide)

Atriplex corrugata (Hates water, ultimately a short shrub, plant in early/late winter)

Woody lilies

Yucca nana

Agave toumeyana bella

Agaves, most hardy sp, let’s be honest. 

Nolina greenei is the smallest/hardiest “Beargrass” but big: best behind the CG.

Lil yellow daisies

Stenotus acaulis

Haplopappus armerioides

Tetraneuris (Hymenoxys) acaulis, scaposa, and argentea

Calylophus lavandulifolius, C. serrulatus

Heterotheca jonesii

Heterotheca ‘GoldHill’

Erigeron liniaris (may need to be low/wetter)

Lil other daisies

Townsendia hookeri (the best/longest-lived), T. glabella (big-ish), T. spathulifolius, T. incana, etc.

Erigeron tener (super)

Aster ericoides ‘Snow Flurries’ can be 2’ or more wide.

Erigeron compositus (come. to. daddy.)

Artemisia frigida- will get too big for some gardens. 

Buckwheats Yo

Eriogonum caespitosum, kennedyi, wrightii (small ssp), jamesii, pulchrum, and more.

Eriogonum umbellatum (ie Kannah Creek) in wetter/shadier spots in Denver

Eriogonum ovalifolium, all spp except niveum.

Eriogonum heermanii (ie, var sulcata) - fantastic. 

Some Eurasians for ya

Acantholimon spp, especially blue leafed ones, not alpine or green-leafed spp.

Limonium minutum

Goniolimon sp that fit in size.

There are surely countless others species yet to be tried…

Limonium minutum

Africans for the right spot: usually wetter

Aloinopsis spathulata

Nananthus transvaalensis

Escobaria sneedii (v leei)

Lil Cactus duh

Escobia sneedii, leei, orcutii, villardii, and probably any hardy sp.

Escobaria missouriensis, vivapara especially.

Mammillaria heyderi/maeiacantha

Echinocereus, most sp, where they fit. In Denver and wetter places, a slope or a rise help keep these drained. 

Opuntia fragilis, small forms like the “potato cactus”

Coryphantha sulcata- delicious.

I know there are more small cacti. South Americans tend to want irrigation. 

P. pachyphyllus


P. laricifoius, tiny, long-lived, hard to find.

P. alamocensis, barbatus, - big plants with wee shadows 

P. moffatii

I know there are many more...

Choice things/Crown jewels/hard to source/Oddballs

Astragalus spathulifolius

Castilleja scabrida

Penstemon acaulis- don’t you dare go pester this in nature.

Leptodactylon spp.

Lepidium nanum

Chaetopappa ericoides- good luck, witches.

Sphaeralcea caespitosa

Chaemachaenactus scaposa- long lived, hard to find seed.

Linum kingii- way cool.

Hoffmanseggia (Caesalpinia) repens. 

Cymopteris bulbosus. Takes years, hates water.

Worth a shot, I haven’t tried them (enough).

Lewisia rediviva

Artemisia assoana.

Erigeron elegantulus

Penstemon linarioides.

Stachys, fuzzy ones

Sideritis sp. 

Salvia… most fuzzy asian ones will probably do, but most are too large

Pterocephalus spp. Not in GJ.

Petrophytum caespitosum of desert provenance. 

Convolvulus boisseri, tragancanthos, etc. 

Phlox ‘Lemhi Gem’

Achillea, miniature spp. like serbica, ageratifolia.

Penstemon petiolatus- perhaps on a north side as it happens in nature.

I have not trialled enough Grasses

Bouteloua hirsuta (Denver, not GJ?)

Bouteloua ‘Zig Zag’ very worth a shot in Denver.

Lycurus pheoides (oh no, this one is good)

Muhlenbergia torryi, pungens.

Eremeoruruefurususus something. Fluffgrass. Annual or nearly so.

Aristida purpurea/longiseta. Often short lived and bad in dog fur.

Acnatherum hymenoides (1-2’ if you have space. Great. It’s been weedy for a rare few)

Hesperostipa comata- big translucent plant, no shadow. 

Buffalograss can work as a “skirt” but will invade/cover rocks in a rainy summer.

I know, I know, there is ruby muhly at Apex, but there is ample space and it gets a little water. 

Koeleria macrantha - someone should try it

Things you’d expect to go without water but won’t (usually)

Arenaria ‘Wallawa Mtn’ (it’s alpine and probably European, actually!)

Arenaria alfacariensis

Delosperma (with some exceptions… or they look bad when stressed. They need sun to be happy but need regular irrigation to be in sun…)


Sedums (lanceolatum, and a few others allegedly have done it)

Sempervivum (also been a report or two but I am dubious. They are usually alpine plants)

Half the Mesembs/Aizoaceae/Iceplant family, generally. They just haven’t persisted without regular, if minimal, irrigation. 

Erigeron scopulinus

Manfreda maculosa

Zauschneria (Epilobium), generally. I wish they did.

Chamaechaenactis scaposa

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Wow, this blog platform is truly horrible to use now. When will we push back against the trend of AI/Clickbait/Advertisement taking over the internet and making it very hard to find good, real, in-depth information any more? How long will we tolerate the threshold being pushed towards us on this and other fronts? 

Wednesday, January 12, 2022

Kenton's Lectures 2022

Some of these are not pinned down for exact time or event yet.

Kenton’s Lectures  2022


Boulder City NV Garden club, 

online 8pm MST

the Modern Crevice Garden

Feb 1-3:

ProGreen  Denver, CO

Crevice garden construction for professionals

Sead Meadow panel discussion with Ross Shrigley and John Murgel

Feb 19: NARGS Rocks: Meadow Gardens conference, host.

Click to visit page and buy tickets!

March 16: Home Garden Club of Morristown, NJ? online?

March 19:

Watnog Chapter NARGS, 10:30 EST online: 

the Modern Crevice Garden

April 13:

Evergreen Arboretum: 7pm online

the Modern Crevice Garden

April 4-8 

Far Reaches Conservancy

Pt. Townsend, WA

Crevice garden annex build

Possible program TBD?

June 9

Plant Select, Denver

June 11th

Berkshire Chapter NARGS with Paul Spriggs

The Crevice Garden

June 20-24

APGA: Crevice Gardens 

with Paul Spriggs and Jeremy Schmidt

Workshop/Build at Cistus Nursery

September 14-16

Urban Growth Conference, Malmö Sweden

Modern Crevice Gardens & Hardy Succulents

Thursday, January 6, 2022

Meadows Versus Rock Gardens. Cagematch or Team Fantastic?

NARGS Rocks: Rock Gardening Does Meadows

A webinar hosted by Kenton Seth. 

Feb 19: 10:30am-4p, MST 

Tickets Here.

Yet another in the varied, successful, and wonderful series created in the last year by NARGS, I am hosting the meadow-garden themed webinar. I am stunned by the caliber of speakers, and especially excited to expose listeners to a few certain folks whom I’d call sleeper talent- amazing geniuses perhaps not known in wide circles. 

A meadow is not a new idea- arguably the classic border and cottage garden is a meadow- it’s really any garden dominated by herbaceous plants. But recently it’s come to mean more grasses and plants grown for wildlife forage or habitat, including bugs. In the zeitgeist of the alarmism of climate change shifting to action, gardeners are broadly embracing their opportunity to genuinely mend the world, starting in their front yard.  

We’ll start with Cassian Schmidt, Director of Hermannshof Gardens in Germany, exemplifies the deepest history in Germany if not the first examples of meadow-style garden concepts. The infamous ornamental grass Karl Foerster is named after one of the great trailblazers from that country. The germanic innovation continues today.

Several more notable public gardeners follow him- Lisa Roper, who has long tended the gravel garden at Chanticleer in PA. (And thus directly inspired dang near everyone gravel gardening in the US. When I was quietly hunting for speakers, most of my prospective folks all showed slides of her garden as the example that inspired them to do what they are doing). Fergus Garret is an established mogul at the Great Dixter- it means a lot when a storied and historical garden not only deeply embraces but pushes the forefront of invertebrate-minded gardening. Krissy Buys from Cornell in NY will talk about two native “lawn” projects of hers, which lay the groundwork for a future of native and threatened plants genuinely being used to replace unused turf. 

My friend Kyle Dallefeld will ring in from Des Moines, Iowa, heart of the tallgrass prairie and some of the richest soils on earth to give us a perspective of rock gardening and tall herbaceous systems- from wild to farmland. Lastly, an old friend Erik Fleischer, of Symbio Studio in Victoria, BC, will bring it all down to earth to talk about practical home-sized garden projects of the front yard scale, and where rock garden techniques have influenced modern seed-grown and habitat-creating garden approaches.

I see a powerful teaming up between the rock garden and meadow worlds, aided by a de-facto blending that has always been there: both rockeries and meadows are totally inspired by nature, representing archetypical biomes of earth. The botanical sophistication of rock garden culture empowers any mission towards biodiversity.  Meadows work in larger areas where rockeries aren’t tenable, and rockeries fit into the increasingly small and topographically awkward garden-able spaces of cities and suburbs.  Together they will make the world a better place for both humans and our other living friends. 

Sunday, August 1, 2021

The Warm-blooded Touchy Carrot Clan

Ipomoea leptophylla, five years without water.

In context of establishing great plants into gardens, I have come to know a certain motley crew of remarkably unrelated and excellent plants that all seem to have the same problems- problems which may explain some of them being so absent in gardens. Lassoing them into a group in my mind has made it easier to deal with their funky personalities, and so I want to tell you who they are, and my trick to skipping the bull and enjoying them at their best.

-Most hate transplanting- some usually die from it.

-They have significant taproots, often hate being in pots, and hate overwintering in a pot even more.

-They don't emerge until it's freaking hot outside: no-shows of spring but kickass bloomers in summer. 

-They are usually big and herbaceous, leaving big old holes when you clean up their great freaking skeletons. A challenge to design with...

-They are too awesome, once in the garden, to give up: They tend to bloom in the worst of summer heat and all will grow without water for me in Western Colorado.

They all look so very different, but if you close your eyes and consider how they behave, I swear they are all the same damn plant.  So who are these rascals?

-Coyote Gourd, Cucurbita foetidissima. This one REALLY hates transplanting.

-Desert Four-o-clock, Mirabilis multiflora.  Many gardeners have noticed that volunteer plants are always tougher than their mom. Probably the least fussy of the lot and comes up a bit earlier.

-Jimsonweed/Moonflower, Datura wrightii, Hardy to say zone 6, it's a classic alley plant in Grand Junction and hardy in hot spots in Denver. 

-Bush Morning Glory, Ipomoea leptophylla. This one is rarely in commerce but lives foreverrrrr when it does get a big ol' root down. With flowers like that you know that it's looks are not the reason it's not popular.  

Cucurbita foetidissima is a giant octopus with shark fin leaves - it needs room!

Now, many of us have tamed them into air-pruning pots, bands, whatever, to grow them in the nursery. Some folks are very careful with the fussy roots. I have had good luck taking half or most of the leaves off of newly planted plants to reduce the root stress- it works really well. But there is an even better way. 

1. Sow them directly in their spot as seed. (no compost or amendments!)

2. In summer (like June/July).  

3. Defend the seedlings from crawling chewing bugs (like with a metal collar made from a beer can) and 

4. Water the living crap out of them when it's hot so they grow big and fat and fast to be a nice size by fall to overwinter with big legs and a full belly. (This means a good soak 1-2x a week when it's above 70F, and stop in fall.)

They will come up strong the following season and be a mature blooming plant without supplemental water or bug defense, far outpacing a plant that was planted and may not have overwintered anyway. The other great advantage is that the taproot is allowed to shoot down uninterrupted like a drill and yield a perfect root system with no traumatic history- no need to re-grow the taproot a year after planting. 

The challenge designing with them? I'm not sure I have a perfect answer- but simply having room to be placed behind other small shrubs or herbs will hide their spring-empty seats from view. It helps if those plants in front can tolerate shade when the thugs do come up and cast a broad summer umbrella over their neighbors. As for their big dead skeletons, chop them up, stomp on them, or grab them like a giant dead bouquet to haul off in one massive load. If you grow the four-o-clock you know what I mean. 

I think the story behind these guys is that most come from light soils whose water drains deeply and quickly (and they chase it with their taproot) and that these plants all specialize on monsoonal summer moisture.  Where I live, summer rains don't always happen, so the native populations don't recruit newbies on those years, like Mirabilis glandulosaThis year of course we are getting hammered with lovely summer rain which has turned the river to mud and is washing away highways like it's California or something, making all the NARGS folks detour on their way to the meeting in Durango next weekend. 

The handsome late July leaves of a datura, in bud, that I sowed in early June.

I feel like there are few more of these kids I forgot to name by species- (help me out and tell me who I forgot) You know how to identify them now and what to do to tame these marvy tigers in your native dry garden. 

Saturday, February 6, 2021

Sources of Expanded Shale and such


There has been discussion among rock gardeners, roof gardeners, bonsai growers, and the crevice people about sourcing expanded shale and other permeable aggregates. These materials are like porous gravel, holding water and nutrients without organic material- which is very useful mixed into crevice garden soil media and in containers to grow alpine or rock plants.

Here is a list I've been compiling:

Haydite (Ohio) 

Seramis (Germany/Europe/UK)

Permatill (by Stalite) North Carolina

Turface (actually calcined clay) or “Pro’sChoice” brand

Trinity Expanded Shale (Golden, Colorado)

Utelite  (Utah)

Soil Mender brand Expanded Shale (Texas)

Cat litter/“Oil-Dri”- coming in bags at the pet or automotive store, these occasionally turn out to be useful expanded shale, calcined clay, or diatomaceous earth, but most of the time are just clay clods- adding water will quickly reveal the truth. A source for desperate times. 

Broken pots- Terra-cotta, porous pots have the absorbent qualities of all the above, but this is not true for vitrified stoneware pots which are fired hotted and not porous. Broken terra-cotta may have been used for a very long time historically by rock gardeners in-the-know! Not a bad plan-B if nothing else is available or you want to dispose of old pots.

Thursday, January 28, 2021

Secrets of Dogtuff, Eryngium leavenworthii, and Amber Wheels

 Ever find out something about a plant that sure as hell isn't in the books about them?

Like Gaillardia 'Amber Wheels' being rhizomatous.  Oh yeah.

Surprise #1

Hard-blooming Gaillardias are anything beyond a short-lived perennial. Usually you get seedlings off the mother plant before she dies. But last year, when I was planting bulbs in a high elevation flower bed designed by Scot Ogden, I saw shallow rhizomes everywhere. I keep an eye on that bed to keep certain nasty rhizomatous grasses out. But these white threads- I followed them back to the plants. Whaaaaaat? I emailed Scot to find out that the Gaillardia was Amber Wheels, a seed strain based on a wild collection by Larry Vickerman of Denver Botanic's Chatfield campus.

Just to make sure, I took root cuttings. They worked.

The original plants have been humming along since 2016 with no sign of getting tired. Fantastic.

Surprise #2.

Eryngium leavenworthii- a Texas version of sea-holly.  I had to try it because some of the coolest designers I know have use it. It's listed universally as an annual. So I got seed in winter, like you do, sowed it in the greenhouse, and planted it out in spring. And it slooooooowly established. I watched those tiny puddles of plants do nearly nothing all year. As the season wore on I grew more sure they sucked for my garden, or sucked in my climate, or I sucked at growing them, and then winter came. And they lingered.

Because they are biennial for me- and a friend in Iowa told me he has the same experience. What the heck? I'm grateful. Just to write it down somewhere: Eryngium leavenworthii is biennial if it isn't annual. 

Surprise #3.

I'm usually pretty careful about adopting new plants too fast because I hate to discover some plant's weakness or worse- its dark secret on a client's dime and in their garden. My friends and Chelsea (native) Nursery are even better about that. The reality of the cutting edge is that it's R&D- it's messy and unknown until tested well.

So I was slow to fully embrace dogtuff, the amazing bermudagrass that is all the rage in cutting-edge gardens in the cold dry American west. (Cynodon transvaalensis) It is native to Africa, was mysteriously found on a ranch in CO, passed between many plantsman's hands until Kelly Grummons found the ideal use for it as a super xeric, no-mow, dog-proof turf. 

I was mostly leery because I was raised in a valley where bermudagrass is a horrible bane to gardens and landscapes. The typical mongrel bermudagrass has ridiculously deep rhizomes, going an average of 18" (45cm) deep invading beds and swallowing your groundcovers with its coarse leaves and dagger-sharp stolon tips and rhizomes that jamb into your feet and easily punctures sweed-cloth. Why would I risk planting a short greener version of that crap?

So I have tested it and been on a mission to find out how badly it spreads underground. I have awkwardly asked to dig post-holes in friend's gardens. Well, whaddya know. It doesn't. Not that I have found. Before I was comfortable with that, I installed a patch for a client who wanted it, but not without containing it with a deeply buried bamboo barrier. In the end that was totally unnecessary. 

Trench and bamboo-proof vest.

Just a month after planting plugs.

What is more- I planted it in our back garden to give us a whopping 6' (2m) wide "lawn" where several paths intersect, and that doesn't require we own a lawnmower at all. We don't. And so on principal, I've never mowed it. In fact, I didn't cut back the dead material last spring to see what would happen and.... nothing. It greened up as per usual.  Lastly- here's the biggest surprise. For fun, I watered it once in 2020. May. One good soak. And I decided to not water it until it looked stressed out, so I could test just how dry it can grow. 

I waited. And waited. In August, at noon, one part looked almost imperceptibly stressed. I waited. Green again until frost.

What!? Kelly told me that during a wet summer in Denver he didn't have to water it. But in Fruita? In 2020 we got 105F (40.5C) with only 5" (125mm) out of our usual 9" (230mm) precip. Our dogtuff grass was satisfied with groundwater- which is 8' (2.3m) down and only in the summer. Wow. It doesn't have rhizomes but somehow the roots can get to water that far down?

I estimate it would be perfectly beautiful with a consistent 2 week watering schedule on any sunny soil. Now, if only I could find a basic irrigation control box that could be programmed to water that little.

Dogtuff is good. It doesn't run.

Sunday, January 17, 2021

A Flame in the Tinderbox: Crevice Gardens in California (and Earth, Generally)

Photo: Michael Uhler

Forced by writing a book on crevice gardens, I started to think about crevice gardens in all climates, which highlighted where they are (or would be-) most useful. The things that make them powerful- biodiversity, recycling, and microclimate creation- have different weights in different places.

Most of this thinking was informed by watching them take off here in Colorado. So, to myself, I predicted the next hot spots: California, because of its longer history of water-use awareness, native gardening, and a big population of gardeners and plant collectors. Then Arizona- one of the recent fastest growing suburban places in the west, but very limited in water. They have an established “desert” aesthetic that liberally embraces new hardscape styles. I think aesthetics may be a big driver there. Then perhaps Texas, with its amazing natural biodiversity and its own gardening identity. 

What I am more blind to, like a typical american, is the rest of the world. The Japanese have a perfect score of adopting something and elevating it into and art and science, while putting their own stamp on it: Aquariums, cars, whatever. A genus of plants is a genus of plants- like Morning glories or Chrystanthemum, until it goes to Japan. It comes back an entirely different thing. They just have a culture of honing, dedicating, and perfecting skill. Can you imagine what they will do with crevice gardens? They’ll leave us looking like cavemen. Get ready to be an old hat.

I think that crevice gardens (can I just call them CGs now?) will continue to fill in within the intermountain West, Midwest and eastern US, where they are already scattered. Same for the UK, Canada, Ireland, Scotland and New Zealand, places all within the well-connected english-speaking rock garden world. I don’t know much about CGs in Australia yet. CGs have been around western places a while and will steadily grow. Same for Europe. But South America, Africa, middle Eurasia, and all the islands- I have only the vaguest of guesses. I think we’ll see isolated and adapted use of CGs in tropical places, since chasmophyte plant forms can shift seamlessly into epiphytes there. The middle east could be incredible- it’s already a strong influencer connected climactically to Arizona and Mexico.

I don’t know enough about China to know when and how things will develop there. The most populous country on earth, I’m sure it will be big. The second biggest? I’m afraid to betray my own biases, but I don’t expect anything big and soon in India. I have no doubt private gardeners or isolated innovators and geniuses will create amazing things, but the country as a whole suffers from a lot of status quo and a glut of sinecures (easy prestigious jobs with high pay and little work or skill). All the public gardens I personally saw there unfortunately suffered from that weight. The hashtag #rockgarden in India is saturated with narcissistic teen selfies at Chandigarh.

I also guessed that Turkey was deeply unlikely to see crevice gardens anytime soon- and boy was I wrong. I lived one summer in Turkey, so the place is a certain home to me. The first public CG is at the Nezahat Gökyiğit Botanical Garden in İstanbul. It’s big, and they feature turkish endemics in a sophisticated way. Then, in SE Turkey: Antalya’s Mediterranean University reached out to Paul and I to build one in marble, no less, but the plan was snuffed by the pandemic. 

The Crevice Garden in İstanbul's NGBB.

Photo courtesy of Mike Smedley, future host and de-facto ringleader of June’s NARGS annual conference. 

But I’d like to swing all the way back to my first prediction: California. I was keeping my ear to the ground when Panayoti was the first to let me know it was happening. 

The Tilden Regional Park, on the foothill-ed edge of Berkley, CA, specializes on California natives, honoring the most floristically diverse state in the union. I was generously filled-in by gardener/builder Michael Uhler and director Bart O’Brien there about their project. In the last two years, they’ve set tons of a glorious rock they call “Mariposa Slate.” They have taken a slow, focused and deliberate approach to maximize and leverage the best of what a CG can do to grow specific plants. Let’s be frank- most of us build something cool and see what we can grow in it. They have taken a more thoughtful path with a focus on Sierra Nevadan alpines. Here is a link to a preliminary newsletter article on it.  

The next issue, Vol 25:1 (2021) will feature a meaty and wonderful article by Michael about the whole history of the crevice garden and a deep look at the plants it was designed to host and their origins.

Photo courtesy of Michael Uhler

Bart says that there are now at least three private crevice gardens that were influenced, spurred, or otherwise affiliated with Tilden Park project. I am reminded of the time when Denver Botanic’s Mike Kintgen put in the first two at Denver botanic. That was the spark that ignited interest in Colorado and well beyond. 

I am holding onto my seat and grabbing for the seatbelt to see what is about to happen in California.