Aubrieta Seeds - Rockcress Seeds - Aubrieta deltoidea

4, 5, 6, 7, 8, 9

USDA Zones 4-9: Grows as a hardy, mat-forming perennial in these zones. It is evergreen in milder climates (Zones 7-9) and semi-evergreen in colder areas (Zones 4-6), where it may die back to the ground in harsh winters.

Best Performance (Zones 4-7): Thrives in regions with moderate summers and cold winters. These zones provide the ideal cool-to-mild conditions for it to establish and produce a spectacular spring flower show without "melting out" in high summer heat.

Hot Climate Zones (8-9): Performance is highly variable and challenging. Aubrieta dislikes high heat combined with humidity (e.g., US Southeast) and may fail. It performs best in Zone 8-9 climates with dry summers (e.g., Pacific Northwest). In all hot zones, partial afternoon shade is essential to help it survive the summer.

Soil Temperature (for Germination): Requires cool soil temperatures between 65-70 degrees F for best germination.

Growing Season (Perennial): This is a long-lived perennial that grows slowly from seed in its first year, often with light flowering. It will reach its peak performance and bloom heaviest in its second and third years, returning reliably each spring. Excellent drainage is required to survive wet winters.

Learn more about USDA Hardiness Zones here

When to Plant (Indoors):

Recommended Method: Start seeds indoors 6-8 weeks before your average last frost date. This gives the slow-growing seedlings a strong head start.

When to Plant (Outdoors):

Direct sow in early spring as soon as the soil is workable, or in late summer/early fall (at least 6-8 weeks before the first hard frost) to allow roots to establish.

Where to Plant:

Sunlight: Full sun (6+ hours). In hot climates (Zones 8-9), a location with partial afternoon shade is necessary.

Soil (Critical): This is the most important factor. Aubrieta must have excellent, sharp drainage. It will rot and die in heavy clay or soil that stays wet. It is perfect for sandy, gravelly, or average soil.

Soil pH: Prefers neutral to alkaline soil (pH 6.5-7.5). If your soil is very acidic, amend it with garden lime.

Location: Ideal for rock gardens, between paving stones, on slopes, or spilling over the top of a retaining wall where water can drain away freely.

How to Plant (Seed Starting):

Depth (Critical): Seeds need light to germinate. Do NOT cover the seeds with soil.

Process: Press the tiny seeds firmly onto the surface of a sterile, moist seed-starting mix.

Moisture: Keep the soil mix consistently moist (but not soaking) by misting or bottom-watering. Cover with a clear humidity dome or plastic wrap to retain moisture.

Germination: Place in a bright location (or under grow lights) at 65-70 degrees F. Be patient; germination is slow and can take 14-21 days.

How to Plant (Transplanting):

Harden Off: After all danger of frost has passed, acclimate your indoor-sown seedlings to outdoor conditions for 7-10 days before planting them in the garden.

Spacing: Space plants 12-18 inches apart to give them room to spread and form a mat.

Growing and Care:

Watering: Water regularly during the first growing season to help the plants establish a strong root system.

Drought Tolerance: Once established (after the first year), Aubrieta is drought-tolerant. Water deeply but infrequently during extreme dry spells.

After-Bloom Care: This is key. Shear back the entire plant by about one-third to one-half immediately after it finishes flowering in late spring. This prevents it from getting "leggy" and encourages dense, tidy new growth.

Mulching: Use gravel, small rock chips, or sand as mulch. This keeps the crown of the plant dry, suppresses weeds, and mimics its native alpine environment. Avoid heavy organic mulch, which can hold too much moisture.