Aubretia (Aubrieta deltoidea) is a tough, mat-forming perennial that transforms rockeries, retaining walls, and garden edges into cascading carpets of purple, blue, pink, and white flowers each spring. Native to the mountains of southern Europe, this evergreen groundcover thrives in well-drained, slightly alkaline soil and full sun. It is one of the earliest perennials to flower, providing colour and nectar for bees when few other plants are blooming.
Top 3 Killers
When to Plant
Sow aubretia seeds in autumn or late winter for the strongest establishment before the heat of summer.
Plant: Autumn (Mar-May) or late winter (Jul-Aug) in temperate and cool zones.
Flowers: Late winter through spring (Aug-Nov), depending on zone and variety.
Aubretia germinates best when soil temperatures sit between 18°C and 20°C. Watch for the first daffodils and jonquils as a phenological cue that spring-flowering perennials are entering their active growth phase.
Sow indoors Jul-Aug or direct sow Mar-Apr. Flowers Aug-Oct.
Sow indoors Aug-Sep or direct sow Mar-Apr. Flowers Sep-Nov. Excellent zone for aubretia.
Marginal zone. Sow Mar-Apr. Best in elevated areas like Toowoomba. Provide afternoon shade in summer.
Sow Mar-Apr. Ensure sharp drainage. Protect from extreme summer heat with afternoon shade or rock shelter.
Site, Soil and Setup
Choose the sunniest, most freely draining spot in your garden. Aubretia performs best on slopes, raised beds, rockeries, retaining walls, and along pathway edges where water runs off quickly.
- Full sun is essential. Six or more hours of direct sunlight each day produces the tightest, most floriferous growth.
- Soil must drain freely. Amend heavy clay with coarse sand, perlite, or fine gravel before planting.
- Target a slightly alkaline pH of 6.5 to 7.5. If your soil is acidic, work in garden lime or dolomite lime (100-200g per square metre) at least four weeks before planting.
- Aubretia prefers lean, low-nutrient soil. Do not add rich compost or manure at planting.
Aubretia does not need crop rotation, but avoid planting in spots where brassica family members have recently suffered from clubroot. As a member of Brassicaceae, it can be affected by the same soil-borne disease.
Container Growing
Aubretia is excellent in containers, especially shallow wide pots, hanging baskets, and troughs where it can cascade over the edge. Use a pot at least 25cm wide and 15cm deep (roughly 5 litres) with large drainage holes.
- 'Cascade Purple', 'Cascade Red', and 'Pixie Pearls' are well suited to container display
- 'Kitte Blue' produces large flowers on a compact plant ideal for smaller pots
- 'Argenteovariegata' adds variegated foliage interest between flowering periods
Use a gritty, free-draining potting mix. Combine standard potting mix with up to one third coarse sand or perlite. Add a pinch of garden lime to the mix if your potting media is peat-based and acidic.
- Water only when the top 2cm of mix feels dry. Over-watering is the most common container mistake.
- 🌱 Feed once in early spring with seaweed solution (30ml per 9L) to support new growth. No further feeding is needed.
- Position in full sun. Rotate the pot occasionally so all sides receive even light.
Sowing Seeds
Aubretia seeds are tiny and need light to germinate. Surface sow onto moist mix and do not cover.
Starting indoors
Start seeds indoors 8 to 10 weeks before you plan to plant out. This gives seedlings time to develop a strong root system.
- Fill seed trays or small pots with a fine seed raising mix. Moisten the mix thoroughly before sowing.
- Scatter seeds thinly across the surface. Press gently to ensure contact with the mix but do not cover.
- Mist lightly with a spray bottle. Cover the tray loosely with clear plastic or a humidity dome to retain moisture.
- Place in a bright spot out of direct sun. Maintain a temperature of 18°C to 20°C.
- Germination takes 14 to 21 days. Remove the cover as soon as seedlings emerge.
- Water from below to avoid disturbing tiny seedlings. Keep the mix moist but never waterlogged.
Direct sowing outdoors
Direct sow in autumn (Mar-May) in prepared soil where plants are to grow permanently.
- Clear the area of weeds and loosen the top 10cm of soil. Mix in coarse sand if drainage is poor.
- Scatter seeds on the surface and press lightly. Do not bury them.
- Water gently with a fine rose attachment to avoid washing seeds away.
- Thin seedlings to 25-30cm apart once they are large enough to handle.
Transplanting
Move indoor-raised seedlings outside once they have at least two sets of true leaves.
- Harden off (gradually expose seedlings to outdoor conditions) over 7 to 10 days.
- Plant at the same depth as the seedling was growing in its tray. Do not bury the crown.
- Space 25-30cm apart to allow each plant to spread into a full mat.
- Water in gently with seaweed solution (30ml per 9L) to support root establishment.
Care by Growth Stage
Aubretia is a minimal feeder that performs best on lean soil. Over-feeding produces soft, leggy growth at the expense of flowers.
💧 Water lightly until established, then reduce. Drought tolerant once settled.
🌱 Minimal feeding. One application of seaweed solution in early spring is sufficient.
✂ Trim back by one third to one half immediately after flowering each year.
Establishment (weeks 1-8 after transplanting)
- Water every 2-3 days for the first few weeks until roots are anchored. Let the soil dry between waterings.
- 🌱 Water in with seaweed solution (30ml per 9L) at transplanting to encourage root development.
- Keep the area weed-free. Young aubretia plants are slow to spread and can be smothered by vigorous weeds.
Active growth (autumn and spring)
- Water only during extended dry spells once the plant is established. Aubretia is drought tolerant and prefers to stay dry.
- 🌱 Apply seaweed solution (30ml per 9L) once in early spring as growth resumes. This is the only feeding most aubretia plants need for the entire year.
- A thin gravel mulch (not organic mulch) around the base helps drainage and keeps the crown dry.
Flowering (late winter to mid-spring)
- Maintain even, light moisture during the flowering period. Do not let the soil dry out completely while flowers are open.
- No feeding is needed during flowering. Excess nitrogen at this stage reduces bloom quality.
- Enjoy the display. Blooms last 4 to 6 weeks. The flowers attract bees and other beneficial pollinators.
Post-flowering and summer rest
- Trim hard immediately after flowering finishes. See Trimming and Shaping below.
- Reduce watering through summer. In hot climates, the plant may look sparse during peak heat. This is normal.
- If growth stalls in poor soil, a balanced liquid fertiliser (NPK around 12-3-8) applied once at half-strength can help, but this is rarely necessary.
Winter dormancy
- Aubretia is evergreen and frost hardy to -15°C. No winter protection is needed anywhere in Australia.
- Do not water during prolonged wet winter periods. Ensure the soil drains freely.
- 🌱 Apply a light side-dressing of blood and bone (50g per square metre) in late winter if the plant looks pale or weak after its second or third year.
Tips and Tricks
- Plant into vertical spaces. Aubretia grows naturally in rock crevices. Tuck small plants into gaps in dry-stone walls, between pavers, or along retaining wall cracks. The sharp drainage in these spots suits it perfectly.
- Use gravel mulch, not organic. Bark chip and straw mulches hold moisture against the crown and cause rot. A 2cm layer of fine gravel or crushed rock keeps the crown dry and the roots cool.
- Take cuttings as insurance. Aubretia is short-lived. Take 5-8cm semi-ripe cuttings in late summer each year and root them in free-draining mix. You will always have replacement plants ready.
- Divide every two to three years. Lift the plant in early autumn, split into sections with a sharp spade, discard the woody centre, and replant the vigorous outer pieces. This keeps the clump healthy and prevents centre die-out.
Trimming and Shaping
Hard trimming after flowering is the single most important maintenance task for aubretia. It keeps the plant compact, prevents woody die-out, and encourages a fresh flush of foliage.
- As soon as the last flowers fade, use secateurs or garden shears to cut the plant back by one third to one half.
- Do not be timid. Aubretia responds well to hard cutting and regrows quickly from the base.
- Water lightly after trimming to help recovery.
- Complete all trimming before late autumn. Cutting too late may remove next season's flower buds.
Companion Planting
As a groundcover flower, aubretia works best alongside plants that share its love of sun and free-draining soil.
- Alyssum - white or yellow flowers create a striking colour contrast in spring
- Candytuft (Iberis) - similar low-growing habit, flowers at the same time
- Arabis (rock cress) - another alpine groundcover that pairs naturally in rockeries
- Daffodils and short tulips - spring bulbs emerging through aubretia mats create a layered display
- Dianthus - shares the preference for alkaline, well-drained soil
- Moisture-loving plants - ferns, hostas, and bog plants need watering that will rot aubretia
- Vigorous groundcovers - fast-spreading plants like ajuga or native violet can smother slower-growing aubretia
- Heavy feeders - plants requiring rich, frequently fertilised soil create unsuitable conditions
Harvesting Blooms
Aubretia is primarily a garden display plant, but its cheerful flowers can be picked for small posies and spring arrangements.
- Pick stems in the cool of the morning when flowers are freshly open
- Cut stems 8-10cm long with sharp scissors or secateurs
- Place immediately in water
- Expect a vase life of 3-5 days
Aubretia's small blooms look charming in miniature arrangements or floating in a shallow bowl. The flowers are not edible. Leaving most blooms on the plant feeds pollinators and keeps the display looking its best.
Common Problems
Pests and Diseases
Aubretia has very few pest or disease issues. Good drainage and full sun prevent most problems before they start.
- Plant in full sun with sharply drained soil to prevent root rot and fungal disease
- Use gravel mulch instead of organic mulch to keep the crown dry
- Avoid overhead watering. Water at the base of the plant in the morning.
- Trim after flowering to improve air circulation through the foliage