New crevice garden at the Ruth Bancroft Garden

A crevice garden is a unique style of rock garden designed to mimic the conditions where plants grow in the cracks of natural rock formations, for example in alpine, desert, or cliff environments. Flat slabs of rock are set vertically, or at a slight angle, with narrow gaps (crevices) between them. This vertical placement creates a unique microclimate that is highly beneficial for plants that don’t like to be wet for long durations. The narrow crevices are filled with a lean, gritty, or sandy soil mix, which drains exceptionally well, keeping the plant’s crown dry. The rocks channel water deep down, encouraging roots to grow long and deep into the cooler, more consistently moist soil below. This helps protect them from surface drought and fluctuating temperatures.

Compared to traditional rock gardens, crevice gardens offer better water conservation, lower maintenance once established, and a more effective way to cultivate difficult-to-grow, moisture-sensitive alpine species. Plants suitable for crevice gardens include saxatile (rock-loving) and alpine plants like Armeria (sea thrift), Dianthus, Penstemon, and Lewisia, as well as many xeric plants, cacti, and succulents. (In this context, the word “alpine” doesn’t specifically refer to the European Alps, but to any mountain habitat.)

The modern crevice garden technique was primarily developed in the Czech Republic by passionate rock gardeners, most notably Zdeněk Zvolánek, in the latter half of the 20th century. These European gardeners were seeking a better way to grow their collection of rare and demanding alpine plants that were struggling in traditional rock garden settings. They observed that these plants thrived best when their roots were forced deep into narrow cracks, replicating natural stratified rock formations. The technique became known as the “Czech style” of rock gardening, characterized by the upright, tightly spaced stones. In the late 1990s and early 2000s, the concept began to gain wider international recognition as Czech gardeners like Zvolánek traveled abroad and constructed major crevice gardens at public institutions, such as the Denver Botanic Gardens, and the Royal Horticultural Society’s garden at Wisley in the UK.

In recent years, the movement has grown significantly thanks to Kenton Seth and Paul Spriggs, whose groundbreaking 2022 book The Crevice Garden (review on the danger garden blog) has popularized the technique, making it accessible to a broader audience, especially in areas concerned with water conservation like the American West. In recent years, larger-scale crevice gardens have been built in the Pacific Northwest at places like the Far Reaches Botanical Conservatory in Port Townsend, Washington, Heronswood Garden in Kingston, Washington, and Cistus Nursery outside of Portland, Oregon. Northern California has two major crevice gardens: at Regional Parks Botanic Garden in Tilden Regional Park, Berkeley, and at the Lake Merritt Rock Garden in Oakland.

Ruth Bancroft Garden

Just a few months ago, in September 2025, work began on a large-scale crevice garden at the Ruth Bancroft Garden (RBG) in Walnut Creek. Designed and shepherded by garden director Walker Young, this pioneering project applies crevice garden techniques to a choice collection of succulents, many of which require maximum drainage, especially in a climate that experiences both hot summers and winter rain. To achieve the necessary conditions, 35 tons of rock from three different Northern California quarries and 35 cubic yards of custom soil mix were brought in to create mounds, which elevate the planting areas and ensure water drains quickly. Plants include succulents like gasterias, haworthias (and closely related haworthiopsis), echeverias, and sedums, South African bulbs and mesembs, as well as plants from alpine regions around the world. The project is partially financed by a grant from the North American Rock Garden Society Western Chapter.

Walker has been creating mounds with rocks for several years now, tucking sensitive plants into cracks and gaps, but the new crevice garden takes this concept to a whole new level.

Through a fortunate set of circumstances, I visited the Ruth Bancroft Garden three times in October and November. The photos below may be a bit redundant, but they show the progress of the crevice garden over a period of six weeks. At the bottom of this post, you’ll find a short video that shows what it looked like on November 14.

October 5, 2025

The backbone of the crevice garden is finished and planting has begun. The rocks were placed to simulate a natural fractured landscape with deep, narrow fissures that protect the plants’ crown while allowing the roots to search for moisture deep within the substrate.

October 11, 2025

More plants have been added. As you look at these photos, bear in mind that each rock was placed by Walker, just so. Like a giant jigsaw puzzle with 5000 pieces.

November 14, 2025

We had a long chat with garden director Walker Young. He used every single rock that was brought in (remember, 35 tons!) and actually needs some more to complete the unfinished edges of the crevice garden. Some of the plants are bullet-proof, but others are experimental, especially fragile alpine plants. They have to survive not only cool and wet winters, but also hot and dry summers. Fortunately, the crevice garden is in a somewhat sheltered location. A year from now we’ll have a much better idea of which plants handle these conditions well and which don’t.

Cyclamen sp.

Gasteria sp. and Haworthiopsis reinwardtii

Haworthiopsis reinwardtii

Myriopteris covillei, one of several dryland ferns in the crevice garden

Echeverias, haworthiopsis, and deuterocohnia

Below is a short video I took on November 14. The quality isn’t the best, but it shows the topography and three-dimensionality of the crevice garden much better than any photo can. There’s no voice track, so you can watch the video on muted.

If you’re interested in learning more about crevice gardens, watch this presentation by Kenton Seth.

© Gerhard Bock, 2025. All rights reserved. To receive all new posts by email, please subscribe here.