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)
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.)
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)
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
Tetraneuris (Hymenoxys) acaulis, scaposa, and argentea
Calylophus lavandulifolius, C. serrulatus
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.
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.
Goniolimon sp that fit in size.
There are surely countless others species yet to be tried…
Lil Cactus duh
Escobia sneedii, leei, orcutii, villardii, and probably any hardy sp.
Escobaria missouriensis, vivapara especially.
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. laricifoius, tiny, long-lived, hard to find.
P. alamocensis, barbatus, - big plants with wee shadows
I know there are many more...
Choice things/Crown jewels/hard to source/Oddballs
Penstemon acaulis- don’t you dare go pester this in nature.
Chaetopappa ericoides- good luck, witches.
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).
Stachys, fuzzy ones
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!)
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.
Zauschneria (Epilobium), generally. I wish they did.