A Short Dogma of Growing Paintbrush

Castilleja miniata in the Aspen. (Populus tremuloides)

I named my late landscape company after Castilleja: Paintbrush Gardens LLC. Now that name refers to my micronursery that supplies my garden designs and also expresses my demented whims in personal plant tastes. 

Here is the way I grow paintbrush myself. There are other ways. I’ll list a few at the end.

1. Chose a species that is native to a similar climate as your own. For example, C. applegatei and latifolia have been good for growers in Washington, Oregon, and the UK. I’ve grown many from the lower elevations of Colorado but struggle with our alpine species. 

Castilleja sessiliflora is so boring it blends right in while in full bloom. Pollinators still find it. It’s one of the easiest to grow and some forms are pink and/or white. 

2. Collect your own seed. For whatever reason, I find my own seed from the last year or two or three germinates better than anything I buy. Usually. Commercial seed is perhaps old or stored poorly. An exception has been the superb seed from Western Native Seed here in CO. 

3. Screen that seed. A decent set of screens makes this really fast, or you can do creative things with folded paper (winnowing) or scraping with a credit card (reenacting Pulp Fiction). 

4. Store seeds in Fridge until you are ready to sow.

5. Sow out in fall, say October. Just two months of cold strat may not be enough. Three is more reliable.  Do it like traditional rock garden plants- low fertility and high porosity soil mix, a fine (not too deep) gravel grit topressing. Use a small 2”-4” pot. (5-10cm)

6. Pull into greenhouse in Jan/Feb. This gets the seedlings going to be big enough to plant this spring, rather than next fall. Bright light and good air movement. Look out for slugs.  Fertilize but gently. I grew half a dozen paintbrush species before I had my little greenhouse, so don’t let this step exclude you.

7. Prick out from one another, pair up with host. Letting the roots touch one another so the Castilleja finds the host easily, putting this unhappy couple in their own pot in March/April. I like to use one year old seedlings of subshrubs or other tough, long-lived and deep-rooted plants so they make a sturdy host. Eriogonum have been shown to be one of, if not the best. Use something easy that likes you.  If I have enough seedlings, I’ll often put two tiny 1/2”(1cm) plants of paintbrush per host for better odds at having one take. Also obviously pair up with a host that likes similar conditions to the species of Castilleja you are growing. I personally only bother to differentiate between mountain species and desert species.  

There was a great study done by Love and McCammon in Idaho, published in Native Plants Magazine, which had at least two big takeaways: Use eriogonums and germinate the hosts and paintbrush separately.  One friend of mine feels that seedlings may parasitize one another. 

Recently I put tiny Castilleja miniata with Penstemon davidsonii, something that happens in nature. 

I remember this better because a friend, David Sellars took a candid shot of me looking at this. 

Short but rugged Eriogonum porteri makes a great adaptable host for a number of dry american Castilleja from pot to crevice garden. Nurseries have long used Artemisia frigida or Bouteloua gracilis for Castilleja integra, which is one of the easiest species.

8. Plant out, barerooted, in April/May/June when the plants are still in active growth but before summer heat (And therefore potential semi-dormancy) has set in. If the plants are pretty leafy and grown when you do plant, I suggest pruning half of their tops off to reduce stress to their roots. Water and watch closely as well as protect from chewing bugs who will take away the other half of the plant. I like to shade them for at least two weeks until they show growth.  Now, water sparingly or to match their homeland rainfall. 

9. Enjoy and boast to friends. Really, savor it. Because plenty of species are not terribly long lived or just don’t persist in gardens.  Many species are only permanent in fairly exact conditions in nature, or in disturbed soil which inevitably settle and mature, excluding those pioneer plants.  Castilleja from dry places often go summer dormant, so don’t freak out if they turn brown in summer. That dryness and sleep might be what keeps them safe from rotting. 

Castilleja flava lived for three, bloomed for two. Maybe I let it get too dry?

Or:

Alternately, you can grow them alone until they are sturdy little lone seedlings and you pair them with a host when you plant them in ground in April. I also like to plant them next to multiple plants to give them diverse backup. Seems to help. 

C. integra with Echinocereus triglochidiatus. Seems the cactus is not happy about this. 

Also alternately, if you do not have a greenhouse or cold frame, you can do your pricking and pairing just a few months later where they grow outdoors, and plant them either the next fall or spring. I think they don’t like life in a pot so that’s why I shoot to get them planted as soon as possible.

I almost hoed this poor volunteer paintbrush. Don’t worry, an earwig ate it a few days later. 

Direct sowing. This works if that seed is absolutely ideally suited to your site.  I cannot underscore enough the danger that slugs and chewing bugs pose on paintbrush- they must be as uniquely tasty as they are uniquely beautiful. One night and one slug can take out my entire year’s crop of seedlings if I’m not religiously vigilant. Troughs or crevice gardens seem particularly helpful in accommodating species from dry climates and mineral soils. 

Some folks have used GA3- gibberelic acid- to bypass cold stratification. I’ve never been good with acid. Some folks use the fridge, but you must watch them carefully in there.  Paul Cumbleton in the UK wrote a great article for The Plantsman about growing them without a host, by taking good care of the plants from the early stages, forcing them to make their own food, and having them live and bloom this way. 

Nothing like a big, wild, unapologetic Rimrock Paintbrush. Castilleja scabrida. 

As hemiparasites, they all seem to have half the root system a plant should have, so they are just more delicate against any kind of stress you give them. In the end, they are elusive for a reason- wonderful and wild. And in wildness is the preservation of the world, right?

(Castilleja integra reseeds around the APEX crevice garden, photo by Tom Freeth)

A Crevice Garden in Christchurch, NZ

The largest city on New Zealand’s South Island wraps around a historical and expansive botanic gardens and park, which itself is outlined by the Avon river like the bezel for a jewel.

There is a new curator, Grant, (above) for the rock garden, and the local alpine plant club, NZAGS is eager to aid him in the complex nuances of Rock Gardens. In turn, Grant has an amazing breadth and depth of horticultural knowledge and experience to infuse into his work and the alpine club. The visionary director of the Christchurch Botanic, Wolfgang Bopp (previously of Hiller Garden in the UK) encourages this connection and exchange between serious hobbyist clubs (which are repositories of expertise) and public gardens; a wise move that many botanics don’t make. I liked the guy instantly because he wore a tiny vase as a jacket pin with fresh flowers in it. 

Anyhow, the finest way to solidify a working relationship between club and botanic was with work: to collaborate on a new exhibit  (see link for video, etc) and renovation in the rock garden- which is where I was fortunate enough to play my role as designer/builder for a crevice garden in the Christchurch Botanic. Crevice gardens are relatively few and new in New Zealand, only in the back garden of alpine gardeners like Michael in Lake Tekapo- but not in public gardens yet. 

We took some time determining how to add a bold new feature without it looking out of place, (“Like a pimple” as Wolfgang said- I like that) and honoring the existing design of the rock garden at large. We wound up siting it partway into the middle of a recently renovated heath and heather collection (Erica/Calluna) but with a few “island” beds across a path, and plan for a few to actually bisect the main path and appear within the alpine garden itself across the main path.

A collection of slivered stones has always looked horrible next to massive boulders to me, so this was just the second time ever (this being crevice garden #41 for me) I’d dealt with that- the solution being to create masses and shapes with the small stones that echo the size and character of nearby large stones. Luckily, the new and old stones are also similar in color.  

The alpine plant club, NZAGS blew me away. They were as serious as any Scottish or British club but more diverse in their plant interests, and were my introduction to the indescribable hospitality, humour, level-headedness, craftiness, and hard-working dedication of New Zealanders. I got to know all of them individually on a plant-chasing field trip, so I felt like I had friends in them by the time we worked together on the rock garden. 

What I was not prepared for was that the club would take what they learned from my lecture so quickly and bravely start setting rocks- diving fearlessly headlong into learning a skill that I have admittedly failed to be able to teach people time and time again. But they learned it. Oh yes. It was my job to ensure the garden design was cohesive and that is was structurally sound as well as practical to grow plants in, so I could hardly keep up with them in not only answering their questions while they all fast-tracked their new skill, but also to guiding the character of the garden to maintain a motif that made it look whole and unified. 

Suzanne, above, did some awesome work in and out of the garden- I realized late-game that she's already  written a blog on the project that is better than mine!  Check it out here. I reckon she will build her own and I won't be surprised if she does some innovation no one has done before. 

I have a lot of experience imagining 3-D objects and spaces in the garden setting; I can envision a crevice garden, finished, in my mind, before a project starts. I must- it is my job. But when we swept the sand and dust off of the stones, and washed it off, I was startled by the beauty of what I saw.  Truly, the quality of the detail of the rock work across the installation- thanks to each volunteer- was far better than if I had been left to do it alone and even spent weeks on it.  I was so humbled by watching in real-time: my passing of a baton of my tricks and experiences to not one person, but a group, and watching them sprint off with finesse ahead of me. I had never experienced that kind of synergy even with people I’d paid as staff for years when I had a landscaping business. It was exhausting and it was amazing. I left with my head spinning and my heart exploding. 

Special thanks go to Joe and Ann Cartman, who were the perfect people to answer all the obscure things I wanted to know about the ecology, plants, animals, and people of NZ, and who also took me to see a wonderful case study of the complexity of disturbed ecologies and the resilience of natives. 

Hamish Brown is the current prez of the club who instils a supercharged combo of smoothness and energy into all happenings. He and I were not above hijacking the golf carts at the botanic. I am indebted to him for helping me during my hurried exit from the country to return home due to the virus. His family and growing style deserve an article on their own. 

A bit on crevice gardening in New Zealand: Sand, rock, and climate.

For americans, it’s best to imagine a coastal California or Washington climate- Eucalyptus and pines thrive. Dryness happens more in summer, but proximity to the ocean means dry is never so extreme as the world’s big continents. There is also a mildness of winters and summers that is not unlike the UK.  Of course, the north island is even milder; (reminded me of the Carolinas) and the interior can be drier than the coasts.  Their Mountains- not small things- create some Mediterranean-dry places and valleys almost as cold as Western Colorado- where my familiar landscapes of vineyards and orchards appear.  And of course- the mountains are shouldered with a real montane weather, and peaked with true alpine. 

Local Alpine gardeners have found that good old sand is an ideal growing medium for troughs, raised beds, and mounds, providing enough mineral nutrition without gravel fines, and not fatally drying out in summer. So this is what we used in the crevice garden on top of an old loam. 

The historic Hallswell Quarry, source of our glorious rock.

While sedimentary rock exists around New Zealand, and even a few outcrops of limestone, the place is mostly dominated by volcanic and metamorphic rocks clothed in acidic soil.  The Crevice garden was privileged enough to use the much coveted Halswel stone, which was used historically all over town, but is no longer quarried- the botanic had special permission to gather new stone from the quarry on account of being used to renovate something historical (the rock garden) and that both are council holdings. (The city government manages both the botanic and the quarry as open spaces/parks.)  Someone said our stone is an andesite; it really did feel and sound like a rhyolite I have used in Colorado. It slivers in irregular wedges characteristic of things like related basalt, which is what the large boulders in the rock garden are.  We used most of the 13 tons (12 metric tonnes) that was gathered for it.  

Gotta love that incredible leopard print rind. 

I can't wait to come back in a year or two and see what they plant, how things grow, and what they discover a crevice garden offers to gardening in New Zealand.

Time for a cuppa tea.

Overlooked Native Dandy: the Circus Onion

One of the first wild things to bloom in lowland Western Colorado (aside from Lomatiums) is Allium macropetalum. I still I cannot think of it by any other name than what my friend Trina calls it.

We once dug handfuls of “Circus Onion” from some land to be developed on the north end of town that sits on clay barrens.  A humble little bulb- one of about 4 local desert species of Allium around here. 

(Like A. nevadense, which makes fat dense creampuffs and a single spiral leaf, or A. acuminatum,  which explores the color affinity to highlighter markers) Since then I’ve learned a bit more about this completely ignored native darling.

It grows like a champ in nasty unirrigated clay soil, or even nice garden soil. And multiplies. It leafs out in fall and winter, and blooms for a long period in early April, standing no more than 4” (10cm) tall. They vary from pure white to mostly rose, with most being a striped intermediate. Some are not fragrant, some smell like an outhouse.  But just a few individuals have a heavenly fragrance!  Making those distinctions with your face a few inches above the dusty earth and your hands on the ground is really... special.

We fell in love with it. It multiplies well from year to year and, just as in nature, makes a wonderful, non-competitive, non-aggressive understory bulb to appear before taller plants, showing up to bloom when their successors are barely emerging. They politely and thanklessly fill an empty niche of early native bulbs for the super super dry garden when it is too dry for Muscari, Scilla, Galanthus, species tulips, and the like. While Denver is usually moist enough for the above, it is too dry in or unwatered cactus gardens of the Great Basin. Some of us don’t like to water our cactus gardens because that just means weeding in between all those spines. 

Knowing we’d not have the windfall of just digging up patches of bulbs in future, I tried to propagate them in pots from seed and bulb division.  They hated it. That is to say, they almost died out entirely, so I frantically planted them in the ground to save them. They hated pots. This happens with some truly wild natives- the best ones.  But what also happens is that genetics from a certain population will break the rule. That is why some wonderful natives you could never buy suddenly appear in the nursery one year.  And it turns out that an Allium I gathered in Las Cruces grew up nicely in a pot, bloomed this spring, smells like cat pee, and turns out to be Allium macropetalum- looks like it has a wide range across the mid southwestern US. 

The Las Cruces form of Allium macropetalum.

Most Alliums are very easy from seed- they need a few months of winter to wake the little seeds for spring germination and a couple years in a pot before being blooming size.  They sleep fine through the summer in their pots in the West, better than most bulbs that get too dry or fry or rot.  Mountain and alpine species are the easiest, and desert/steppe species can be a little trickier (or not)- but you don’t know until you try. Throwing the seed strait into your garden is even easier. Pests and grazers will usually avoid eating them. So I encourage any hikers and naturalists out there to look for their local Allium- they are usually secretive cherubs and harbingers of spring- and collect some seeds and welcome them home in your native garden.