False Rockcress Plants: Learn How To Grow Aubrieta Groundcover

Aubrieta (Aubrieta deltoidea) is one of the earliest bloomers in spring. Often part of a rock garden, Aubretia is also known as false rockcress. With its darling little purple flowers and dainty leaves, Aubrieta will scramble over rocks and other inorganic items, covering them with color and distracting the eye. Aubrieta groundcover is also remarkably drought tolerant once established and can handle the harsh heat of a full sun rockery. Read on for some tips on the care of Aubrieta and how to use this magical little plant in the garden.

Aubrieta Growing Conditions

Aubrieta is a perennial suited for United States Department of Agriculture zones 4 to 8. This temperate to cool region plant can spread up to 24 inches (61 cm.) over time and forms lovely purple carpets of color in spring. It is non-invasive and self-sufficient for the most part. Learn how to grow Aubrieta in your landscape so you can enjoy its charm in your border, rockery or even container garden.

False rockcress plants prefer full sun and well-drained soil. The plant prefers sites that are rich in lime. These easy-care plants are also adapted to partial shade locations but some blooms may be

sacrificed. Aubrieta is a member of the mustard family, a notoriously tough group of plants. It is deer resistant and tolerant of drought once established.

Once the full heat of summer is released, the plants tend to die back a bit and in fall much of the foliage will disappear in cooler climates. Aubrieta groundcover can tend to get a bit scraggly over time and responds well to shearing back after bloom or in fall.

How to Grow Aubrieta

Aubrieta grows well from seed. It is easy to establish and requires a minimum of water as the seedlings grow. Choose a sunny spot in the garden in early spring with well-draining soil or alternately start seeds indoors in flats 6 to 8 weeks before planting outdoors.

Remove any debris and till soil to a depth of 6 inches (15 cm.). Sow seeds on the surface of the soil. Water gently with a diffuser attachment to prevent drowning seeds and pushing them under too much soil. Keep the area moderately wet but not soggy.

Once seedlings appear, keep weed pests from the area and thin plants to one every 10 inches (25 cm.). Over the spring, false rockcress plants will gradually spread out to cover the area in a thick carpet. Young plants may develop a few spotty flowers but a full flush of blooms should not be expected until the following year.

Care of Aubrieta

These little plants couldn’t be easier to manage. Cutting the plants back after bloom can discourage seeding and keep the plants compact and tight. Every 1 to 3 years dig up the plant and divide to prevent center die out and propagate more plants for free.

Keep Aubrieta moderately moist especially during the growing season. False rockcress has few disease or insect pest issues. The most common problems occur where soil is clay or drainage is poor. Make sure you amend soil and check for percolation prior to planting them out.

There are several cultivars available with flowers of red, lilac and pink. These lovely plants are beautiful cascading over a wall or even a container. They tend to look a little sad in early spring, as some of the foliage will have dropped but quickly recover with warming temperatures and spring rain.

How to grow aubrieta

Because taking cuttings tends to weaken stock plants, many aubrietas today are seed-raised. The Mead Nursery (01373 859990; www.themeadnursery.co.uk) in Wiltshire has a fine collection, although it does not do mail order. Nurserymen Stephen and Emma Lewis-Dale rate the double violet-blue ‘Blue Beauty’, and the dark magenta-red ‘Gloria’, for their vibrance. The subtler ‘Bicolor’ has lavender and purple flowers that eventually fade to white so it shows all three colours at once; ‘Greencourt Purple’ AGM is a trailing purple with frilly flowers.

With so many varieties disappearing over the past 70 years, it’s a good thing that there is a collection at Leicester Botanic Garden. Ring 0116 271 2933 for more information.

Growing tips

Alan Bloom, who always had a succinct way of summing up a plant, records that aubrietas “have no liking for richness”, an attribute he also shared. Thin soil, preferably alkaline, in full sun, is their preferred diet. That said, aubrietas seem to flower happily on many garden soils.

The technique to keep aubrietas going year after year is to shear them hard as they finish their display, so that they develop a new cushion of tight foliage. Cuttings can be taken, and ideally these need to have three inches of brown stem below the rosette of foliage. The technique is to tug them away with a heel rather than cut them. This can be done in September and October (when the cushion of foliage is dense), or in late summer. A cold frame is ideal as it keeps the root cool. Sow seeds in spring.

Good companions

Because all aubrietas – naturally suited to cold, high-altitude climates – tend to look ragged in hot summer months, find a partner that follows on afterwards. Possibilities include Dianthus alpinus, Geranium cinereum ‘Ballerina’, or ‘Lawrence Flatman’. Rock roses (Helianthemum nummularium) also fit in well and these sprawling plants also like lime.

Where to buy

  • Ice Alpines, Lyehead Road, Bewdley, Worcestershire (01299 269219; www.icealpines.com);
  • Ashwood Nurseries, Ashwood Lower Lane, Kingswinford, West Midlands (01384 401996; www.ashwoodnurseries.com)

Reader offer

Telegraph Gardening readers can buy six Aubretia ‘Blue cascade’ for £8.95 or buy 24 for £17.90 – half price. Please send orders to Telegraph Garden Service, Dept. TL207, 14 Hadfield Street, Old Trafford, Manchester, M16 9FG. Make cheques/postal orders payable to Telegraph Garden Service or call 0161 848 1106 for debit/credit card orders. Quote ref. TL207 when ordering. To buy online visit www.gardenshop.telegraph.co.uk/offers/. Delivery within 28 days to UK addresses only. Module grown plants supplied.

Aubrieta Blue Cascade

Buy this popular rockery perennial from Telegraph Garden Shop

Latest reader offers at gardenshop.telegraph.co.uk

How to grow aubretia

What better to herald the arrival of spring than a cascade of purple

You know spring has arrived when you see walls covered in a purple waterfall of Aubretia. This alpine member of the Brassica family needs full sun and dry conditions so is ideal to plant in the top of a wall where you will see it to its best advantage, cascading down the sides. It looks fantastic grown with bright yellow Alyssum montana ‘Mountain Gold’ and snow white Arabis caucasica ‘Snowcap’. They originally come from Central Asia and Europe where they grow in poor soil on rocky limestone screes and outcrops. Most of the varieties come in lots of shades of purple and lilac but if you search you can get pink and dark red forms.

Planting

They need a really well drained spot in full sun, ideally on top of a wall or in a container where they can cascade over the edge, as they can reach a drop or 60 – 90cm (2 – 3’). They prefer an alkaline soil but do seem tolerant of a neutral growing medium. Incorporate some horticultural grit into the compost and a little lime if it is neutral. Don’t enrich the soil with any fertiliser just a little leaf mould.

Aftercare

Water when first planted but once established it should take care of itself. Top dress with a 50/50 mixture of horticultural sand and leaf mould with a small handful of lime added, in spring. Once it has finished flowering shear it over to keep it nice and tight and prevent it going straggly, just don’t go right into the old woody growth. It should then grow new leaves which will keep the nice tight cushion form.

Propagation

Take cuttings from mid to late summer by pulling off a shoot. They seem to take better if pulled off with a heel rather than being cut. Select a shoot with a nice rosette of leaves at the top and about 5 – 10cm (2 – 4”) of brown stem. Place it in a really gritty cutting compost, add extra grit if necessary, and place it in a cold frame to root.

Problems

They are relatively pest and disease free but if they are not sheared over every year they can become a bit bald and woody in the centre. You can try and regenerate the centre by placing some gritty compost over the bald patch, obviously if it is growing down a wall this is not an option. You could try cutting it right back or the best option could be to just pull it out and replace with a new plant. Once it starts to go a bit woody take cuttings a couple of years before needed.

Recommended varieties

Purple and lilac varieties are to be found in early spring in all garden centres but there are a few a little bit different:

  • A. argenteovariegata – silver edge to the leaves
  • ‘Chianti’ – deep wine red
  • ‘Gloria’ – rich magenta
  • ‘Red Swan’ – deep red with cream edged leaves

Aubrieta is a cute little perennial ground cover. Its blooming sets on early in the season, with its first flowers blooming in April.

A summary of Aubrieta facts

Name – Aubrieta
Family – Brassicaceae
Type – perennial
Height – 6 to 8 inches (15 to 20 cm)
Exposure – full sun
Soil – ordinary

Flowering – April-May
Foliage – evergreen

Planting aubrieta

Aubrieta is planted in fall if possible, but planting can also be performed in spring, in non-freezing weather.

Aubrieta loves old walls, rocky ground and cascading cliffs, where it will produce a very ornamental impact.

  • Aubrieta loves sunbathed locations.
  • Place about 5 to 10 specimens to a square yard (1 m²) to create amazing ground cover.
  • Water abundantly at the beginning.

Aubrieta in pots and containers

Aubrieta is a flower that is very well suited to growing in a pot or a garden box.

  • Plant your aubretia in a pot with special flower plant soil mix.
  • Water on a regular basis, whenever the surface soil is dry.

Pruning and caring for aubrieta

You’ll appreciate your aubrieta when you discover how easy it is to care for, and how abundant its blooming is.

  • Cut the stems back after flowering.
  • Every 2 or 3 years, divide the clump to easily propagate and multiply your aubretia.
  • For spectacular blooming every year, fertilize your garden soil at the end of winter.

Aubrieta and potential diseases

Aubrieta is a plant that resists most diseases and fungi very well, but it sometimes is hit by downy mildew.

This happens when heat and moisture occur at the same time. A layer of whitish webs appears on leaves and stems.

  • Here is how to fight downy mildew.

As for parasites, you might spot a few aphids from time to time.

  • Here is how to get rid of aphids.

All there is to know about aubrieta

This cute ground cover plant produces roundish bushy balls with purple blue flowers.

From the beginning of spring, it bears hundreds of flowers to the point of actually crowding out its own leaves.

Both hardy and cold-resistant, it can grow in a hole in the wall, along edges or in rocky terrain.

It is often compared to a cute flowered pillow, and is just as suited to growing in pots or garden boxes as it is growing in the ground with other aubrieta plants.

Smart tip about aubrieta

You can add special perennial organic fertilizer after the blooming.

  • Also, watch out for aphids.

Aubrieta Seeds – Rock Cress Whitewell Gem Ground Cover Seed

Groundcover Specifications

Season: Perennial

USDA Zones: 4 – 9

Height: 4 – 6 inches

Width: 12 – 23 inches

Bloom Season: Mid spring to early summer

Bloom Color: Violet purple

Growth Rate: Moderate

Environment: Full sun to partial shade

Deer Resistant: Yes

Planting Directions

Temperature: 68F

Average Germ Time: 14 – 21 days

Light Required: Yes

Depth: Seeds must be covered thinly

Soil Type: Well-drained, pH 6.5 – 7.5

Sowing Rate: Approximately 2000 Aubrieta seeds covers 40 square feet

Moisture: Keep seeds moist until germination

Plant Spacing: 12 inches

Note: For detailed directions for indoor and outdoor planting, please

Care & Maintenance: Aubrieta

Rock Cress (Aubrieta Hybrida Whitewell Gem) – Grow this terrific perennial from Aubrieta seeds. Aubrieta Whitewell Gem, commonly known as Rock Cress, is an extremely popular rock garden plant and a familiar sight in the spring garden. It forms a low cushion of evergreen leaves, literally smothered by flowers for several months. This Rock Cress variety has flowers in various shades of purple to violet, over grey-green leaves. These ground cover plants should be trimmed lightly immediately after blooming, to encourage a thick mounding habit. Rock Cress plants are an excellent choice for a rock garden in sun or partial shade, growing over rock walls, or in alpine troughs, containers, or in mass plantings for a flowering ground cover. Aubrieta plants do take light foot traffic.

Sow Aubrieta ground cover seed indoors 6 – 8 weeks before the last expected frost date. Use starter trays using a sterilized mix. Press the Rock Cress seeds into the soil and thinly cover. The Aubrieta seeds need light to germinate. Transplant into the garden 12 inches apart after frost danger has passed. After frost season has passed, Rock Cress ground cover seeds can be directly sown into a prepared seedbed outdoors.

Shake ‘n Seed – We are now offering shaker bottles filled with our seed starting matrix: rich soil, gardening sand, water absorbing crystals, and starter fertilizer. This not only helps dispense your seed, but it gets it off to a great start! Simply remove lid from shaker bottle, add seed from packet, put back on lid, shake the bottle vigorously for 15 seconds, and then shake your way to beautiful new plants! Use Shake ‘n Seed over good quality soil, and then gently water to keep seed moist until it sprouts. Great for ground covers or mass planting flower seeds.

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