How to Build a Crevice Garden for Beginners

Step-by-step construction of a crevice garden using vertical flagstone slabs and gritty soil.

DIY Crevice Garden

One of the most popular forms of rock gardening today is the crevice garden which uses flat stones installed vertically to create deep planting pockets. They offer a unique opportunity to showcase alpines and other drought tolerant plants. See how to create one step-by-step in this DIY article.

Garden Gems Crevice Garden Project
How to Build a Crevice Garden Step-By-Step
Crevice Garden Through the Seasons
Saving Mangaves Over Winter

Crevice gardens have become one of the most popular forms of rock gardening in recent years, especially as conserving water and connecting to nature have become priorities for many home gardeners. By sinking flat stones vertically into gritty soil that has exceptionally good drainage properties, you can create a one-of-a-kind garden where alpines and other drought tolerant plants shine and thrive.

We’ve all seen small scale plants we’d love to grow but would get lost in our garden beds. Crevice gardens are the perfect place to display them where their unique traits can be showcased rather than crowded out.

Narrow spaces between stones and deep, cool soil allow plants that are naturally well-adapted to growing in mountainous regions or rocky soil to flourish in crevice gardens. Since many of these plants are sun-loving and adapted to growing without a lot of moisture, the best place to locate a crevice garden is in full sun. Take care not to site one where automatic irrigation goes off frequently or for a long period to water other nearby plants or the lawn.

Crevice gardens can be created at any scale – from small troughs to large expanses in the ground. The difference lies not in the types of materials used, but in their size and quantity. If you are new to this style of gardening or on a tight budget, consider starting with a small crevice garden and then expanding later if you enjoy it.

Tools and materials used to build a basic crevice garden:

Flat slabs of stone such as flagstone, slate or sandstone
Gravel
Topsoil or compost
Alpine, succulent and drought tolerant plants
Shovel
Rake
Garden fork
Trowel
Wheelbarrow

DIY Crevice Garden Project

What to Expect

The time it takes to build a crevice garden depends on the size. A tiny crevice garden crafted in a container could take less than an hour, but large crevice gardens like the kind you might find at a botanical garden could take months to complete. The crevice garden in our project pictured here was completed over a few days’ time.

Once completed, you’ll need to keep the newly installed plants watered for the first month or two until their roots are established. After that, water only when the soil is dry several inches down, which could be as little as once a week or so depending on rainfall. Keeping the soil relatively dry and mulching with a 1-inch thick layer of gravel will cut down greatly on the need for weeding. Overall, crevice gardens are a very low maintenance garden style.

Our Garden Gems Crevice Garden Project

The premise behind our crevice garden pictured here was to make better use of an underutilized part of the yard. The area is located in full sun within a large gravel bed where raised vegetable troughs are hooked to drip irrigation. The crevice garden borders a frequently used wood mulch path and is not watered by automatic irrigation. The means of watering include rainfall and hand watering with a hose or watering can once every 7 to 10 days.

In addition to making good use of space, this crevice garden solves the issue of gravel spilling over into the wood mulch path and adjoining lawn. Small, gemlike annuals and perennials as well as showy mangave plants are easily admired in this unique setting. Maestro^® hummingbird mint, Stardiva^® fan flower, ‘Lemon Purrfection’ catmint and Rock ‘n Round^® stonecrop draw in pollinators which helps to boost the yields of the vegetable plants in the troughs.

Recommended Plants for a Crevice Garden

See what we planted in our Garden Gems Crevice Garden.

ANNUALS

Maestro^® Coral and Maestro^® Gold Agastache

Flambe^® Yellow Chrysocephalum

Silver River^® Didelta

Mojave^® Fuchsia and Mojave^® Mango Portulaca

Stardiva^® White Scaevola

Lemon Coral^® Sedum

ART & SOL^® MANGAVE

‘Aztec King’

‘Lavender Lady’

‘Moonglow’

‘Purple People Eater’

‘Silver Fox’

PERENNIALS

‘Pink Diamonds’ Dicentra

‘Lemon Purrfection’ Nepeta

Rock ‘n Low^® ‘Boogie Woogie’ Sedum

Rock ‘n Round^® ‘Popstar’ Sedum

How to Build a Crevice Garden Step-By-Step

With the right materials and a plan, building a crevice garden is a surprisingly straightforward project. Here are the steps we took to build ours.

STEP 1: Clear the Area

Start by clearing the spot where you plan to build your crevice garden. In our case, the area was covered with a 4-inch layer of pea gravel on top of weed barrier fabric laid over the native sandy soil. We started by pulling back the gravel and fabric and moving it out of the way.

In your case, you might be removing plant material, sod or wood mulch. Aim to clear and excavate the area to a depth of about 6 inches.

STEP 2: Loosen the Underlying Soil

After you’ve cleared the mulch and plants from the crevice garden area, you’ll be left with a dense layer of soil underneath. The goal is to have a 6 to 12-inch layer of very well-drained soil for your crevice garden plants to grow in. If your soil is heavy clay, construct a raised berm for your crevice garden to facilitate drainage. The base of the berm can be constructed with coarse gravel.

For our crevice garden, we built it in an area where the top few inches of soil were sandy loam and the native soil below that was very sandy. Both soil types naturally have excellent drainage properties so there was no need to create a raised berm. However, the weight of the pea gravel had compacted the soil a bit, so a garden fork was used to loosen and aerate it to a depth of about six inches.

STEP 3: Mix the Planting Soil

The ideal planting soil for crevice gardens is a 50/50 mix of gravel or a gravel/sand blend and nutrient-rich topsoil, humus or compost. Bagged garden soil can also be mixed with gravel to create the planting soil. Mix the ingredients together thoroughly in your wheelbarrow with a shovel.

For our crevice garden, we used a mix of 50% pea gravel and 50% garden soil which contained a blend of humus, compost, topsoil and shredded bark. Your planting soil should look approximately like the soil pictured here when it’s ready to be used.

STEP 4: Spread the Planting Soil in the Bed

You’ve mixed up your planting soil, so now it’s time to fill your crevice garden bed. If you mixed your soil in a wheelbarrow, it should be easy to dump it into the bed. Use a rake to level it out and then you will be ready for the next step where you’ll really see your crevice garden start to take shape.

STEP 5: Set the Flat Stones in Place

Gather the flat stones you’ll be using for your project and sort them by size. If you will be using stones for edging as pictured here, set those in place first to keep the soil from spilling out of the bed when you set the others.

This is where crevice gardens differ in appearance from rock gardens. In crevice gardens, you’ll be installing the stones vertically rather than laying them flat on the surface of the soil. Aim to sink the stones a minimum of 4 inches deep, but preferably 6 to 12 inches deep. This will create deep crevices filled with cool, gravely soil for the plants’ roots to grow down into. Doing so will ultimately aid in drought resistance, cutting down on the need for supplemental water.

Crevice gardens have a natural style that mimics an outcropping you might find on a mountainside. Stagger the placement of the flat stones to achieve the look pictured here. Most should point in the same general direction, but not all be spaced equidistantly.

Here’s a look from the other end of our crevice garden. At the ends of the bed, the stones were rotated to give the appearance that they are flowing into the corners and around the curves.

STEP 6: Install Mangave in Clay Pots

To provide extra flair and textural interest to our crevice garden, we included five Art & Sol^{^®} mangave plants. Since they are not cold hardy where this garden is located, they were planted in terra cotta pots that could easily be pulled up and brought indoors for the winter.

The mangaves are focal points of this crevice garden, so we chose their placement first before the other plants were installed. Digging down so the bottom 75% of the unglazed clay pots were below ground, it kept the soil cool but not too moist. The exposed lip of the pot made it easy to remove in the fall and also fit the look of the garden.

STEP 7: Stage the Remaining Plants

This is where your creativity really takes root. Using the remaining plants you’ve gathered for your crevice garden, set the pots into the bed where you think you might want to plant them. Consider traits like color, texture, size and bloom time as you work through the process. Keep tweaking the placement, even coming back to it the next day to make more changes before planting.

In our crevice garden, we used a combination of smaller scale, all-season flowering annuals mixed with hardy perennials that bloom at various times. Some had tall spiky flowers, others were heart-shaped or buttonlike. By sticking with a somewhat limited palette of pink, yellow and blue or purple, we maintained a cohesive look down the length of the bed.

Tuck the smallest plants in the crevices created by the vertical stones and use larger gaps for bigger plants and spreading varieties. For instance, smaller scale Stardiva^® fan flowers or succulents work well in tighter spots, while ‘Lemon Purrfection’ catmint needs more room to spread so it won’t obscure the stones.

STEP 8: Plant Your Crevice Garden

Once you are happy with the staging of the remaining plants, use a trowel to plant them in your crevice garden. Help the plants’ roots establish more quickly into the gravelly planting soil by shaking off some of the potting soil and using the gravel/soil blend you’ve mixed up to backfill the holes.

When you are all finished planting, spread a
1-inch thick layer of clean gravel mulch on top of the entire crevice garden.

Pictured here is a look at our freshly planted and mulched crevice garden.

Crevice Garden Through the Seasons

See how our crevice garden matured through the season. Don’t miss how we handled the mangaves before winter arrived at the end.

STEP 9: End of Season Care for Crevice Gardens

At the end of the growing season, remove all of the annuals and cut back the perennials in your crevice garden. Unlike mulched garden beds, you don’t want the decaying foliage or leaves that blow in from surrounding trees to mix into the gravel.

Remember that the plants you are growing in your crevice garden are not accustomed to the humus-rich soil that decaying plant matter would create. In the wild, alpine plants grow on exposed rocky areas and mountainsides in very lean soils where plant debris does not collect.

Saving Mangaves Over the Winter

We wanted to save the mangaves from our crevice garden to use again the next year. Since we had planted them in sunken terra cotta pots, it was easy to pop them back out of the ground in the fall before temperatures dipped into the 50s. In their place, we set plastic grower pots to hold the spots until the plants were reinstalled the following spring.

Our potted mangaves spend the winter in this sunporch where they get plenty of light but stay cool and slightly dry so their growth rate is slowed. Store them above 60°F over the winter or grow them indoors as a houseplant. Extended cool temperatures can cause them to decline, and if they freeze, you will need to start over with fresh plants the following year.

If your mangaves have grown too large over the growing season, look for smaller offsets or “pups” which may have popped up around the main rosette. They can be separated from the mother plant and repotted into fresh soil to use in your crevice garden the following year.

Note that if your mangave flowered, the rosette from which the flower stalk emerged will not live another year, so it can be discarded. This trait is inherited from their Agave parentage. The rosette that produces a flower dies, and smaller offsets fill in its place the following year.

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