Plant Profile: Purple Rock Cress (Aubrieta deltoidea)

A wildflower native to the Mediterranean and Asia Minor, purple rock cress is a member of the mustard family, Brassicaceae, that also includes cabbage, broccoli, and stock. It grows 4-6″ tall and has  silvery-green foliage of spoon-shaped to oval leaves that covers rocks and spaces as it spreads forming lovely mounds of vegetation.  In spring, the loose clusters  of 4-petaled lavender to deep pink flowers are held above the semi- evergreen foliage.   Purple rock cress is especially attractive as a ground cover or edger, between stepping stones, in crevices, or spilling over a garden wall or out of a planter. It is a good choice for cottage, Mediterranean, and rock gardens but  should be treated as an annual or biennial in the South where it is short lived due to humidity and high night temperatures.   The genus name, Aubreta, honors Claude Aubriet (1669-1743) a French botanical artist.  The specific epithet, deltoidea, comes from the Latin word deltoidius, and means triangular.

Type: Herbaceous perennial.

Bloom: Clusters of lilac blue flowers in spring.

Size: 4-6” H x 12” W

Light: Sun to lightly shaded.

Soil: Average, light, well drained, neutral to slightly alkaline.

Hardiness: Zones 4-8.

Care: Shear back by ½ after flowering to prevent legginess.

Pests and Diseases: None of importance; but stems may rot in heavy clay soils in winter.

Propagation: Seed collected in mid summer; layering and cuttings after flowering; clump divisions are difficult but possible.

Companion plants: Arabis, Basket-of-Gold, tulips, moss pink, candytuft, spring flowering shrubs and trees.

Outstanding Selections:

• ‘Novalis Blue’ (deep violet-blue)

• ‘Bresshingham Pink’ (pink)

‘Red Carpet’ (red)