Androsace–often called rock jasmine–is a low growing alpine plant that produces small rosettes of hairy leaves and stemless or short-stemmed tubular flowers singly or in umbels. Androsace is often a selection for miniature rock gardens. It is mostly grown by alpine plant specialists.
There are about 100 species in the Androsace genus, almost all are mat- or cushion-forming perennials. Androsace requires almost perfect drainage; outdoors they do best on gravelly banks in rock gardens. Androsace does best outdoors grown in the company of alyssum, rockcress, and aubrieta which can offer some shelter from the sun to Androsace.
Alpine plant collectors often grow Androsace indoors where drainage is easily monitored.
Get to Know Androsace
- Plant type: Perennial
- Growing zones and range: Zones 5 to 7
- Hardiness: Hardy to Zone 5
- Height and width: Trailing plants are mat or cushion forming to just a few inches high; plants can spread to a few feet wide.
- Flowers: attractive alpine plants that resemble primroses.
- Bloom time: Early summer to fall
- Uses: Especially good for a sunny rock garden.
- Garden companions: A. sarmentosa with alpine columbine (Aquilegia alpina)
- Common name: Rock jasmines
- Botanical name: Androsace
- Family name: Primulaceae
Where to Plant Androsace
- Plant Androsace in full sun. In hot summer regions, plant in afternoon shade.
- Androsace grows well in poor, sandy, or slightly alkaline soil. The soil must be well-drained.
When to Plant Androsace
- Set out container-grown plants in spring.
- Sow seed outdoors in spring or in a cold frame in autumn.
Planting and Spacing Androsace
- Set Androsace 6 to 8 inches (15-20cm) apart; most varieties will spread via runners to three times planting distance.
- Sow seeds 1/8 inch deep in a cactus or succulent mix when starting plants indoors.
How to Water and FeedAndrosace
- Water Androsace from below to keep the neck and foliage dry to prevent disease.
- Indoors grow Androsace in well-drained soil that is equal parts potting mix and grit, with grit surrounding the collar. Indoors, Androsace is best watered from below.
- Outdoors grow Androsace in a scree bed, in vertical crevices in rock work, or in moist gritty soil.
Androsace Pests and Diseases
- Androsace can be attacked by aphids, especially indoors.
- Androsace is susceptible to rust, leaf spots, or downy mildew.
- Separate the rossettes and replant in spring or early summer.
- Sow seeds in a cold frame in autumn.
Androsace Varieties to Grow
- Androsace chamaejasme mat-forming perennial bears white or pink yellow-eyed flowers in umbels in late spring.
- A. ciliata bears deep pink flowers in spring and early summer.
- A. lanuginosa is a trailing, mat-forming plant with silver-gray foliage and pink-lilac blooms in mid- to late summer spreads to 3 feet wide.
- A. primuloides trailing plant with long runners; leafy rosettes are covered with silvery hairs; pink flowers appear in clusters on 5-inch stems.
- A. sarmentosa has rosettes of light green leaves and attractive, rosy pink flowers in late spring and early summer.