Wall rock cress is an outstanding spring-blooming groundcover for rock gardens and dry, sunny spots in zones 4-7. It's easy to care for and produces a carpet of pure white flowers so thick, it almost hides the foliage. After blooming, wall rock cress sports gray-green leaves that keep their color throughout the year.
Wall rock cress (Arabis caucasica) shares several traits and a common name with rock cress (Aubrieta deltoidea), but they are of different genera. Both are members of the Brassicaceae family which includes cabbage, broccoli, Brussels sprouts, and mustard. Both are early spring-blooming perennials that bear striking pink, purple, or white flowers. But wall rock cress is less common than common rock cress and has larger foliage. Wall rock cress and common rock cress also share similarities with wallflower (Erysimum spp.), a spring and summer-blooming perennial in zones 3-10. Use combinations of the three related plants to create vibrant bursts of color across otherwise tough landscapes.
Wall Rock Cress Overview
Where to Plant Wall Rock Cress
The key to success with wall rock cress is good drainage and full-sun exposure. Its low-growing nature makes it an excellent choice for planting along paths and walkways. Or, when planted on a slope or green roof, wall rockcress blends seamlessly into landscape. It also works beautifully in containers or as an edging plant at the front of a garden border.
This easy-care ground cover is a fine choice for rock gardens and trough gardens—especially when paired with other alpine-type plants like thrifts and lavender. Because it roots in as it grows, you can also use wall rockcress to creep over walls and fill in the pockets between stones.
How and When to Plant Wall Rock Cress
Plant nursery-grown or small wall rock cress plants in the spring or fall. Dig a hole twice as wide as the plant’s root ball and just deep enough for your plant to sit at the same level in the soil as it is in its container. Transfer the plant from the container to the hole but avoid overhandling the roots. Backfill the hole with the displaced soil and tamp the soil down firmly. Water well. If planting more than one wall rock cress plant, place them 12 to 18 inches apart.
If planting between rocks or along a rock wall, fill the gaps with gritty, alkaline, well-drained soil and secure your wall rock cress plants in the pockets. Water well and keep the plants moist as they establish themselves (twice weekly in dry weather). A drip irrigation system behind the wall works best but you can also soak the surface of the wall with a garden hose and spray nozzle.
Wall Rock Cress Care Tips
Wall rock cress is easy to manage in sunny spots with gritty or sandy well-drained soils. The evergreen perennial makes a great ground cover and grows easily in the crevices between rocks. It also attracts early-season pollinators, including bees and butterflies, to spring landscapes.
Light
In a sunny spot, this perennial is practically carefree. Wall rock cress demands full sun—at least eight hours of direct light per day. If it doesn't get enough sun, it won't bloom well and is more susceptible to root diseases.
Soil and Water
For successful wall rock cress, well-drained soil is essential—the faster the soil drains, the better. This makes wall rock cress an ideal pick for neutral to slightly acidic gardens with sandy or gravelly soil. If your soil has a high clay content, plant wall rock cress in a container or raised bed.
Wall rock cress, like other rock garden plants, is drought tolerant. Water new plants regularly (once daily for 2 to 3 weeks) in dry weather. Once established, wall rock cress plants need watering only when the soil is dry.
Temperature and Humidity
Wall rock cress is native to areas of Western Asia and the Middle East, so it fares well in areas with cool summers. The evergreen perennial prefers temperatures between 40˚ and 90˚ Fahrenheit and dry to moderate humidity. In areas that experience hot, humid summers, the plant tends to languish. Prolonged exposure to high temperatures may kill the plant.
Fertilizer
Well-planted wall rock cress may not need fertilizer, but an occasional once-yearly application of a balanced, slow-release fertilizer may boost growth. Apply it early in the growing season when the foliage is dry. Brush excess fertilizer off the foliage to prevent fertilizer burn.
Pruning
After flowering, cut your wall rock cress back by half to encourage bushier new growth. This practice will also reduce the likelihood of leggy bare patches—a common occurrence for aging wall rock cress plants.
Potting and Repotting
Wall rock cress is great for containers in sunny locations. Use a pot with ample drainage and fill it with a well-draining succulent potting mix. Add the plant and secure it by tamping the soil around the root ball. Water your wall rock cress regularly and deeply throughout the establishment phase. Once established, water the plant whenever the soil feels dry. Apply a balanced, slow-release fertilizer once annually at the beginning of the growing season. As the plant grows, it will fill the container and maybe even cascade over the side. Once blooming is finished, cut the plant back by half to maintain lush, compact growth.
Plan to repot or divide your container-grown wall rock cress every 2 to 3 years. Begin by watering the plant to help ease the roots from the pot. Tip the plant on its side and gently pull the plant out by the base of the stem being careful not to damage the roots. Place the plant in a new container filled with fresh succulent potting mix.
Pests and Problems
Wall rockcress has no major disease or pest issues—although aphids and fungal leaf spots can occasionally be a problem. Also, if you have overly wet soil, watch out for root rot, crown rot, rust, and mildew.
How to Propagate Wall Rock Cress
The easiest way to propagate wall rock cress is via seed, cuttings, or division. Divide your wall rock cress every 2 to 3 years in the spring or fall. To start, dig up a healthy, established plant and use your fingers to gently divide it into 2 or 3 sections, each with a healthy root system. Replant the divisions approximately 12 to 18 inches apart.
To propagate via cutting, select a healthy non-flowering rosette from an established plant and use sharp, sterile shears to cut it just below a node. Remove the leaves from the base of the stem and plant the cutting in a terra-cotta pot filled with a mix of perlite and all-purpose potting mix. Water the cutting well. Place the container in a cool place (50˚ to 60˚ Fahrenheit) out of direct sunlight. Keep the soil evenly moist until the cutting takes root.
To propagate via seed, you can sow the seeds directly in your garden in early spring. Scatter your wall rock cress seeds on top of the soil and gently press them in approximately 1/8 inch. Water with a mist (to avoid displacing the seeds) and keep the soil evenly moist for 1 to 2 weeks as the seeds germinate.
Types of Wall Rock Cress
Wall Rock Cress ‘Compinkie’
The ‘Compinkie’ wall rock cress cultivar bears sweetly fragrant rosy-pink flowers from midspring to early summer. It grows 6 to 8 inches tall in zones 3-9.
Wall Rock Cress ‘Rosabella’
The ‘Rosabella’ cultivar of Arabis caucasica bears dusty rose-color flowers with yellow centers from mid- to late spring. As temperatures rise, the lightly scented flowers fade to a paler pink. ‘Rosabella’ grows low and dense, typically reaching only 5 or 6 inches at maturity in zones 4-7.
Wall Rock Cress ‘Variegata’
As the name implies, Wall rock cress ‘Variegata’ features variegated light green leaves edged in soft yellow. It blooms with sweetly-fragrant, snow-white flowers from midspring to early summer and grows 6 to 8 inches tall in zones 3-9.
Wall Rock Cress ‘Little Treasure Deep Rose’
This wall rock cress cultivar is carpeted with sweet, purplish-pink flowers from early to midspring. It is hardy in zones 3-9 and has a bushy, compact growth habit that remains only 4 to 6 inches tall at maturity.
Wall Rock Cress 'Flore Pleno'
Arabis caucasica ‘Flore Pleno’ has lovely, long-lasting, double-petalled white flowers from late winter to late spring. It also features evergreen foliage with oblong, toothed grey-green leaves. It typically grows in a dense mat just 4 to 6 inches tall in zones 4-8.
Wall Rock Cress 'Snowcap'
The 'Snowcap' cultivar of wall rock cress bears so many fragrant white blossoms, it looks like a snowdrift from early to late spring. The rest of the year, the evergreen perennial features a dense mat of gray-green foliage. It grows 6 to 8 inches tall in zones 4-8.
Wall Rock Cress 'Pixie Cream'
Arabis caucasica 'Pixie Cream' boasts billows of creamy yellow blossoms (each with a tiny yellow center) from early to midspring. The mounding groundcover grows 6 to 8 inches tall in zones 3-7.
Companion Plants for Wall Rock Cress
Creeping Phlox
Like wall rock cress, creeping phlox (Phlox subulata) is a low-mounding groundcover that offers cheery flowers each spring. Creeping phlox thrives in full sun and neutral to slightly acidic soil. It is drought-tolerant once established and needs little extra care besides a post-frost trim. It seldom tops 6 inches tall and is hardy in zones 3-8.
Dianthus
Dianthus (a.k.a. "pinks") are quintessential cottage garden flowers (in zones 3-10) that come in candy-colored shades of pink, purple, red, white, and yellow. They offer a stunning contrast to the stark white blossoms of most wall rock cress cultivars. The 'Firewitch' cultivar, for example, features fringed, magenta, clove-scented blossoms and grass-like, blue-green foliage. Dianthus requires little care when planted in full sun and well-drained, neutral to slightly alkaline soil. Like wall rock cress, dianthus won't tolerate overly wet soil. So, let it dry out between waterings.
Glory of the Snow
Glory of the snow is a harbinger of spring and one of the first to bloom after the last frost. In fact, they occasionally show up while snow is still on the ground. The most common variety, Chionodoxa forbesii, features blooms with a striking white center and blue-tipped petals. Like wall rock cress, glory of the snow prefers full sun and neutral to slightly acidic (6.0-7.0) well-drained soil. It is hardy in zones 3-8.
Rock Cress
They share a common name and family classification, so it makes sense to plant common rock cress and wall rock cress together. Common rock cress is an evergreen perennial (in zones 4-9) that forms splendid mats of color in the spring and—as the name implies—is at home in a rock garden. Like its familial counterpart, it prefers full sun and well-drained soil. But unlike wall rock cress, common rock cress blooms come in vibrant shades of pink and purple. So, plant them together to create alternating clouds of pink, purple, and white.
Wallflower
It's hard to talk about rock cress and wall rock cress without also considering wallflowers. Native to southern Europe, wallflowers are cool-season plants hardy in zones 3-10 that come in an abundance of colors—perfect to pair with clouds of rock cress. Wallflower is a short-lived perennial or biennial that prefers full sun and well-drained soil. They vary in size from low groundcovers to small shrubs, but the Erysimum 'Orange Bedder' cultivar bears bright clusters of orange flowers on compact, 1-foot-tall plants.
Frequently Asked Questions
- Is wall rock cress invasive?No. Wall rock cress is not classified as invasive, but can grow and spread aggressively in favorable conditions. To control its spread, cut the plants back by half after blooming and regularly divide existing plants. You can discard unwanted divisions, replant them in separate locations or containers, or give them away to gardening friends.
No. Wall rock cress is not classified as invasive, but can grow and spread aggressively in favorable conditions. To control its spread, cut the plants back by half after blooming and regularly divide existing plants. You can discard unwanted divisions, replant them in separate locations or containers, or give them away to gardening friends.
- Can wall rock cress be used between pavers?Wall rock cress doesn't hold up to foot traffic, so it's not the best choice for planting between paving stones. For pathway plantings, look for something sturdier like creeping phlox, Irish moss, or sedum.
Wall rock cress doesn't hold up to foot traffic, so it's not the best choice for planting between paving stones. For pathway plantings, look for something sturdier like creeping phlox, Irish moss, or sedum.
- Is wall rock cress deer-resistant?Yes! Wall rockcress is deer (and rabbit) resistant, so you’ll enjoy its springtime color show even if your yard is frequented by these four-legged visitors.
Yes! Wall rockcress is deer (and rabbit) resistant, so you’ll enjoy its springtime color show even if your yard is frequented by these four-legged visitors.