If at first you don’t suceed, plant and plant again

One of my most lustful plants has been the super cute Euphorbia clavarioides var. truncata. I first ran into this fascinating poinsettia cousin at the Denver Botanic Gardens in the 1990s, and have subsequently killed it 5 times, prior to the construction of our crevice garden. Now, our specimen below is 2.5 years old and thriving. The key is perfect drainage and no water in the winter.

Below is a giant clump, which we saw in the wilds of South Africa in 2005. These massive clumps are considered to be well over a century in age, so our little patch has a lot of growing to do.

Image of Euphorbia clavarioides var. truncata HCG form growing in our crevice garden.
Euphorbia clavarioides var. truncata HCG form
Image of Euphorbia clavarioides var. truncata in the wilds of South Africa.
Euphorbia clavarioides var. truncata in the wilds of South Africa.

Stunning bergia

Looking lovely in the garden today is the fall-flowering geophyte, Sternbergia sicula. This Mediterranean native is found in the wild growing on alkaline hilly sites. Some taxonomists list it as a subspecies of the more common Sternbergia lutea, but it seems consistently smaller. At JLBG, our plant thrives in the crevice garden. Hardiness is Zone 6a-8b.

Sternbergia sicula flowering in the crevice garden
Sternbergia sicula in the crevice garden

Cat Whiskers Cactus

Our planting of Glandulicactus wrightii is looking quite lovely as we head into fall. Sadly, few folks take time to closely examine the fascinating and intricate arrangements of cactus spines. Glandulicactus wrightii, which is native to Texas and adjacent Mexico has amazingly long, hooked spines that resemble cat whiskers. Long term winter hardiness is hopeful here in Zone 7b, since the seed from which this was grown came from a population at 5,000′ elevation on the New Mexico/Texas border.

Glandulicactus wrightii in the crevice garden
Glandulicactus wrightii

Little Big Man

Most highly prized rock garden plants originated somewhere other than the Southeast US. One notable exception is Bigelowia nuttallii, or if you prefer common names, Nuttall’s rayless goldenrod. This fascinating plant resembles a whisk broom that just swept up a spilled bottle of mustard.

Named after English botanist/zoologist Thomas Nuttall (1786-1859), who lived in the US from 1808 until 1841, this fascinating plant, grown by rock gardeners worldwide, is native in only a few locations from Georgia west to Texas.

Bigelowii nuttallii makes a tight evergreen clump of needle-thin leaves, topped from mid-summer until fall with 1′ tall sprays of frothy yellow flowers…yes, those are actually flowers, but without the typical showy “rays”. Full sun for at least half a day, and good drainage are the key to success with this very easy native perennial. Hardiness is Zone 5a-9b.

Bigelowia nuttallii
Bigelowia nuttallii
Bigelowia nuttallii

Stingray in the Garden

We love the spineless Agave bracteosa ‘Stingray’ in the garden. We’ve had these dotted throughout the garden since 2017, and so far, with good drainage, they’ve handled our winters quite well, which is certainly not normal for a variegated century plant. This particular species prefers part sun to light shade. Hardiness is Zone 7b/8a and warmer.

Agave bracteosa Stingray in the garden
Agave bracteosa ‘Stingray’ in the garden

Baccharis-foliaged Beardtongue

We are enjoying the rare Penstemon baccharifolius this summer in our high/dry crevice garden. This species is native to limestone ledges up to 6,500′ elevation from the Edwards plateau in Texas south into Northern Mexico. This species hates our summer rains, and we had given up on growing this until we built our alkaline crevice garden a few years ago. Now it thrives, growing in 3′ deep Permatill gravel.

More pricks

It’s been quite a floral extravaganza this spring in the dryland garden sections. Here are the latest of our flowering barrel cactus that have bloomed recently at JLBG. All of our cactus are growing outside without any winter protection in our zone 7b garden. The key for most is simply good soil drainage.

Coryphantha sulcata
Echinocereus coccineus
Echinocereus papillosus var. angusticeps
Echinocereus reichenbachii var. baileyi
Echinocereus stoloniferus
Echinocereus x roetteri
Echinopsis ancistrophora
Escobaria dasyacantha SB601
Escobaria vivipara var. neomexicana
Lobivia atrovirens var. ritteri
Lobivia haemantantha
Lobivia thionantha
Notocactus apricus
Notocactus floricomus
Notocactus x subluteus (submammulosus x roseoluteus)
Trichocereus 20-07 (‘Big Time’ x Iridescent Watermelon’)

Hot Ice Plants

Delosperma cooperi and Delosperma ‘Kelaidis’ have formed a lovely union in our crevice garden, where they grow in pure Permatill gravel. The key to growing ice plants in a hot, humid, rainy climate is excellent drainage.

Formanek’s Bellflower

The Greek bellflower, Campanula formanekiana has been superb in the crevice garden this spring. This amazing monocarpic (dies after flowering) species take three years to flower, and when it does, it puts on one heck of show. It’s namesake was Czech botanist, Eduard Formanek (1845-1900). We’re hoping for a good seed set. Hardiness is Zone 7a-9a, at least.

The Crevice is “Woke”

The crevice garden has “woke” for spring, with early flowering plants in full gear. Here’s a shot of one small section, featuring Delospema dyeri and Iberis simplex (taurica). We hope you can visit in person for the second weekend of our spring open house, May 6 – 8, 2022.

Meet Urophysa

Unless you’re a serious plant nerd, you’ve probably never heard of the plant genus, Urophysa. This small genus of only two species in the clematis family (Ranunculaceae) is only found growing in Karst cliff crevices in a few limited provinces of South Central China. In other words, they are quite rare. Urophysa henryi was originally named Isopyrum henryi, when it was thought to be a brother of our native Isopyrum biternatum. Urophysa is now considered most closely related to the famed half-columbine, Semiaquilegia adoxoides.

While the Chinese people mostly use Urophysa henryi as a medicinal treatment for bruises, etc., we prefer it as a winter-flowering gem in the rock garden. Here are our plants, which began flowering in our rock garden, just as we turned the page on the new year, 2022.

Winter Onions

Starring in the rock garden in early December is the amazing Allium virgunculae ‘Alba’. This delightful dwarf allium to 8″ tall is similar to the better known and slower offsetting Japanese Allium thunbergii. Allium virgunculae, which typically has lavender flowers, hails from Japan’s far south Kyushu Island.

Holy Zauschneria, Batman!

Try as we might, we have been epic failures trying to grow the showy southwest native Zauschneria (now epilobium) in our garden, due to the combination of high humidity and torrential summer rainfalls. No matter where we tried them in the rock garden, they quickly expired. That was in the years BC…before crevice. Here is our plant of Zauschneria canum var. arizonica ‘Sky Island Orange’, a David Salman selection, planted in early 2018 and still thriving in our urbanite crevice garden. Not bad for a plant that doesn’t grow here.

Long-leaf Buckwheet

We admit to a long-standing case of buckwheat envy. Every visit to the worlds great rock gardens, such as the Denver Botanic Garden, leave us lusting to grow the rock garden genus, eriogonum. We’ve killed many members of the genus, since they truly hate our humid and wet summers. Even our crevice garden was no help in keeping these alive, even including our reportedly easy-to-grow Appalachian native, Eriogonum allenii. After almost giving up several times, we can finally declare success with the Texas native Eriogonum longifolium, from our East Texas botanizing expedition. Here’s our clump in full flower, and quite happy in one of the rock garden sections. Granted, it’s not as stunning as some of the species that thrive in Denver, but hey, we can now check that genus off the list.

Eryngium longifolium

Late Summer Rains

We are fascinated with the wonderful genus zephyranthes (rain lilies). Zephyranthes are unobtrusive, summer-flowering bulbs that can fit in any garden, with a flower color ranging from yellow to white to pink. The great thing about zephyranthes is the lack of large foliage that often accompanies many other spring-flowering bulbs, so site them in the front of the border, or in a rock garden to be best appreciated.

Zephyranthes are one of our specialty collections at Juniper Level Botanic Garden, with 25 species and 257 unique clones. Here are a few of the zephyranthes blooming this morning in our alpine berm. You can view our entire zephyranthes photo gallery here.

Zephyranthes ‘Heart Throb’
Z. La Bufa Rosa group white
Z. La Bufa Rosa group
Z. ‘Star Spangled’

Rockin’ Rose

We’ve tried for years to grow Helianthemum, the European native rock rose, which is highly prized by rock gardeners. Over the last 35 years, we’ve failed miserably…until we built our crevice garden. Here, it is currently, thriving in our soil mix of 50% Permatill (popped slate).

Helianthemum ‘Belgravia Rose’

A Concrete Idea

Unless you’ve been hiding under a piece of concrete, you’ve no doubt heard of our crevice garden experiment, constructed with recycled concrete and plants planted in chipped slate (Permatill). It’s been just over three years since we started the project and just over a year since its completion. In all, the crevice garden spans 300′ linear feet and is built with 200 tons of recycled concrete. The garden has allowed us to grow a range of dryland (6-12″ of rain annually) plants that would otherwise be ungrowable in our climate which averages 45″ of rain annually.

One of many plants we’d killed several times ptc (prior to crevice) are the arilbred iris, known to iris folks as ab’s. These amazing hybrids are crosses between the dazzling middleastern desert species and bearded hybrids. Being ready to try again post crevice (pc), we sent in our order to a California iris breeder, who promptly emailed to tell us that he would not sell them to us because they were ungrowable here. It took some persuading before they agreed to send our order, but on arrival, they became some of the first plants to find a home in the new crevices. Although we’ve added more ab’s each year, the original plantings will be three years old in August. Here are a few flowers from this week.

Iris are just a few of the gems that can be found in our “cracks”, continuing below with dianthus. As we continually take note of our trial successes, more and more of those gems will find their way into our catalog and on-line offerings…as long as we can produce it in a container. Please let us know if any of these strikes your fancy.

If that’s not enough, here are some more shinning stars currently in bloom.

If any of this seems interesting, you probably should be a member of the North American Rock Garden Society…a group of similarly afflicted individuals. If you are specifically addicted to cracks, check out the nearly 2000 strong, really sick folks on Modern Crevice Gardens on Facebook

It’s pretty seedy around here

In addition to spring, one of the things we look forward to most each year is the members only seed exchange list from the North American Rock Garden Society.

This amazing list of plants, shared by members from around the world, is truly the place to find seed of rare, hard-to-find plants for rock gardens and pretty much any kind of garden. The seed list typically offers 3000-4000 different plants annually…probably the best in the world. The first round of distribution in January of each year is limited to 25 different seed types (35 if you donate seed), and the second round, which just went live, allows members to select another 100 varieties. We just got out order submitted, and now anxiously await their arrival. 

We think the seed exchange alone is worth far more than the annual dues, but there’s so much more from tours, to meetings, to networking, and a great journal. So, if you want to become a seedaholic, here’s your path to addiction!