Crevice Gardens are starting to peak in bloom, like mine here, which is probably why the International Rock Gardening Conference is about to happen Wednesday in Prague. Oh, I'l be there, yes, thanks to Denver's Rock Garden Club: RMC-NARGS, who graciously sponsored my trip and for whom I'll be reporting everything I dig up. Just the best crevice gardens on the planet will be on show, that's all, and the world's finest plant-collecting talent will be presenting programs.
Stay tuned for updates this week as Paul Spriggs and I dig deep into Czech rock garden history and pick every rock garden innovator's brain for every trick they have.
Iris acutiloba ssp. lineolata. These things always bloom when I'm out of town. So I schedule a trip, then go a day later so as to catch them in bloom the day I leave... It and its onco iris kin are the reason for the crevice garden's construction, and luckily they like it. Next door to it is a native mint shrub: Monardella odoratissima, and it grows in the West Elks in Colorado (where I probably got my seed) and in the La Sals, which are the backdrop to Arches National Park outside of Moab, Utah.
An old friend. Or foe. "Frenemy" as we millenials say. An aggressive friend. Colorado native skullcap, Scutellaria britonii, is an shameless underground spreader and must either be put in check every spring it shows up everywhere or planted in a place where it can go nuts. Think 4-7 feet (1-2m) expansion underground per year. It gives spring weeds like Dandelions something to contend with; I am trying it as an underplanting for warm season clump grasses. It goes dormant soon after blooming. You should see the piles of pearl-necklace like underground rhizomes.
New to me, and an exciting Southwestern US native which not only seems small enough for a rock garden, even crevice garden (said to be a limestone chasmophyte in nature) but is red! Salvia henryi, grown from Alplains (NM) seed, has been super easy to germinate and grow in the home nursery. I'm excited to try it in the ground; I think it will nicely replace the habit of Verbascum rupestre which had to be kicked out of the garden for its terrifically agressive reseeding. Except this is red! Red!
Many people have asked if Joshuatrees would grow here in Grand Junction, CO. (Yucca brevifolia) Here is the answer: seed-grown plants ( I think young is the key- most transplants fail) by Don Campbell are about 12 years old and taking on real character, several feet taller than a person now. CSU extension office demonstration gardens, at the Mesa County Fairgrounds- this is the Cactus Club's section.
It's amazing how natives quickly fill the niches weeds had. Oenothera caespitosa and Sphaeralcea munroana take to the cracks!
Spring number two, the radio station garden is filling in nicely. Stanleya pinnata (yellow) does most of its growth in very early spring for a big brassicaceous romp in Late April/May- the desert US answere to Asia's Eremurus. The Penstemon eatonii, perhaps thanks to a snowy winter (read: well charged soil) has reseeded madly, and we're not stopping it. Next year will be a firestorm.
In the ongoing quest to find the perfect way to grow Paintbrush (Castilleja), here is Castilleja integra planted with two plants as hosts: Penstemon secundiflorus (which can be short-lived) and Echinocereus triglochidiatus/mojavensis (Which is long-lived - the Claret Cup Cactus). My feeling is that the best host is a strong host; for Castilleja seems capable of killing weak plants. Now, I favor small, established shrubs like Black Sagebrush, Artemisia (tridentata v.) nova, Yucca sp, Agave, et cetera. In a perfect world, you will plant a new Castilleja with it's roots touching a healthy plant which has been there and established for a few years. It's working.
Penstemon acaulis, luckily two plants here, promises good seed this year. I pray it doesn't spill away before I get home to collect it. A testament to the efficacy of the clay- laced crevice.