Aubrieta, a cheerful ground cover, is a great candidate for edging your paths or tucking into stone walls. After the profuse flowers have faded, the grayish-green foliage maintains a handsome mat that covers bare areas under leggy roses or between paving stones on a garden path. These plants are far more common in Europe than in North America. The genus name derives from Claude Aubriet, a European landscape artist from the 17th century.
|Common Name||Aubrieta, false rock cress|
|Botanical Name||Aubrieta spp.|
|Plant Type||Perennial, herbaceous|
|Mature Size||4-6 in. tall, 12-24 in. spread|
|Sun Exposure||Full, partial|
|Soil pH||Acidic, alkaline|
|Flower Color||Pink, purple, white|
|Hardiness Zones||4-9 (USDA)|
Aubrieta thrives best when planted in well-draining, alkaline soil in full sun. As a member of the mustard family, this is a tough plant that requires little care. Aubrieta is rarely bothered by insect pests and it is considered deer-resistant. Once established, it has good drought-tolerance.
Aubrieta plants shine in full sun, but will also grow in part shade. For best results, grow plants where they will receive at least a half-day of sun. Plants that grow in too much shade will lose their compact, mounded appearance, take on a leggy look, and have sparse flowers.
Aubrietas like a lean, rocky, alkaline soil with a pH between 6.5 and 7.5, which mimics the soil found in their native alpine habitats in southwestern Europe. If the pH is low, increase it with the addition of lime.
Aubrieta plants need a moderate amount of water, but they don't like wet feet.
Temperature and Humidity
Aubrieta plants grow best in areas with cool summers that mirror their alpine climate. Periods of high humidity are fine; in fact, the cool, damp climate of Great Britain or Washington state is where you are most likely to find extraordinary specimens of aubrieta plants.
Aubrietas grow in lean soil and need no supplemental fertilizer to make beautiful blooms. At most, occasional watering with compost tea is all the feeding aubrieta plants need.
Types of Aubrieta
Most aubrieta sold in the nursery trade are cultivars or hybrids. Popular varieties include:
- Aubrieta x cultorum 'Rokey's Purple' is among the most commonly seen aubrieta in gardens; it features bright violet flowers.
- Aubrieta x cultorum 'Doctor Mules Variegated' offers a completely different look; it's important to know, however, that variegated types may revert to green, so prune away any all-green stems that form.
- Aubrieta gracilis alba 'Snowdrift' is an all-white cultivar.
Aubrieta can get a bit scraggly after blooming. In midsummer, the foliage tends to die back and will benefit from a hard shearing. Keep it tidy by trimming plants back after flowering. Use shears, and trim no more than half the plant's growth at any one time.
Aubrieta can be divided in the early fall:
- Dig up the entire plant with a shovel.
- Tease the clump apart with your hands or a garden fork.
- Replant the divisions 12 inches apart in a new location at at the same depth as the original plant Water it well and keep it moist until you see new growth.
How to Grow Aubrieta from Seed
Aubrieta can be hard to find as nursery plants, therefore many gardeners grow it from seed. Note that seeds collected from your cultivar or hybrid plants won't produce plants true to type so it is best to start with seeds from a seed company.
- Sow aubrieta seeds in seed flats indoors on top of sterile potting mix. The seeds need light for germination, so press seeds down but don't cover them.
- Keep the seeds moist at about 68 degrees Fahrenheit. Germination will occur in two to three weeks.
- Harden the seedlings off for about a week before planting them in garden soil or in permanent pots.
Potting and Repotting Aubrieta
Aubrieta complements the container garden as a trailing plant, softening container edges. Plant it as a companion to other rock garden flowers with similar growing needs, like dianthus.
Pot up your aubrieta plants with a lightweight all-purpose potting soil. A potting mix meant for cacti is also appropriate for aubrieta plants. Take care not to bury the foliage when potting up aubrieta. There are a few inches of brown stem beneath the foliage, and this is the working area of the plant when repotting. Lift the foliage, and carefully mound soil around the stems and roots to secure the plant in its place.
Aubrieta does not require winter protection, unless it's grown in a container in a climate with heavy freezes. In that case, the roots needs to be protected. Wrap the container in burlap and bubble wrap, or place it inside an insulating silo.
Common Plant Diseases
Plants growing in damp, shady areas may experience downy mildew. You can prevent this fungal disease by providing enough light and spacing for air circulation.
Good drainage is important to prevent root rot. Use gravel, vermiculite, or another non-organic soil amendment that will help drainage without lowering soil pH.
How to Get Aubrieta to Bloom
Failure to bloom or sparse blooms are likely to due to lack of light. Aubrieta blooms at its best in full sun.
Where should I plant aubrieta?
Aubrieta makes a perfect pocket plant for garden walls and rock gardens and it provides good erosion control on hillsides. The plants have a very small footprint and can establish a deep root system in the soil behind a retaining wall, while foliage and flowers can spread up to 18 inches or more, giving the appearance of a living wall.
What's the difference between aubrieta and creeping phlox?
The flowers and form of aubrieta and creeping phlox (Phlox subulata) are so similar as to be indistinguishable at first glance. Both plants grow as a creeping mat, spreading across the border's edge or trailing down walls. However, creeping phlox plants are more heat- and drought-tolerant than aubrieta, which may account for its preference in American gardens.
Does aubrieta spread?
The plant has a trailing growth habit and benefits from pruning to bring it back into shape but it does not spread in any uncontrollable manner.
Saharan, G. S., et al. Downy Mildew Disease of Crucifers: Biology, Ecology and Disease Management. Springer, 2017
Cox, Jeff. Perennial All Stars: the 150 Best Perennials for Great-Looking, Trouble-Free Gardens. Rodale Press, 2002