Aster Seeds

Aster Seeds

Annual asters are half-hardy, not to be confused with the late-flowering hardy perennials they're related to, like Michaelmas daisies. These bushy, free-branching plants have large, solitary, daisy-like flower heads, in late summer and autumn, sometimes up to the first frosts in good seasons. Modern varieties have many flowering shapes, resembling feathery doubles, incurved peonies, ostrich feathers, pom-poms and even a tiger's paw!

Flowers can be up to 15cm/6in across and are a firm favourite with flower arrangers. Varieties like Cut Flower Mixed are ideal for the cutting garden. Colours include white, light and dark pink, red, blue, purple, violet and yellow. They're perfect for beds, borders and large pots on the patio. 

How to grow Asters

Asters can be sown indoors during March-April in gentle heat in a propagator or windowsill, at a temperature of 15-20°C/60-68°F. Sow at a depth of 1.5cm/1/2in in good-quality seed compost. Once germinated, move to a cooler, light position to prevent legginess. Thin out to trays, modules or pots when seedlings are large enough to handle. Harden off in late May and plant out from June onwards, after all risk of frost has passed.

Seeds can also be sown outdoors from April-May, in their flowering position. Keep the seedbed moist and thin out to final spacings of 45cm/18in.

Asters like a sheltered site in fertile, neutral to alkaline, moist but well-drained soil in full sun, although some, like Duchess Mixture, will tolerate a little shade. Tall varieties and those with large flower heads will need staking - arrange a network of twiggy branches that the plants can grow through for a less obtrusive effect. Keep removing dead flower heads to encourage further blooms.