How to Grow Aster (Michaelmas Daisy)
Perennial
Michaelmas daisies are traditional late-season asters, carrying clouds of starry flowers when summer borders are winding down. Colours range from white and pale blue to pink, violet and purple, often with golden centres. They are invaluable for extending the garden season and provide a busy source of nectar for bees in autumn.
Planting
Plant asters in April or May, after the last spring frost, or in early autumn where winters are milder. Give them sun, fertile soil and reliable moisture without waterlogging. Space plants 40 to 60 cm apart to improve air circulation, as crowded growth can encourage powdery mildew. Water thoroughly while establishing. In Scotland and cooler northern gardens, spring planting is generally preferable so plants settle before winter.
Care
Mulch in spring to retain moisture, water during dry spells and stake taller cultivars before they flop. Pinch out the growing tips once in late May or early June to encourage bushier plants and more flowers. Remove tired stems after flowering, then cut all old growth down in late winter. Divide clumps in spring every few years and discard weak central sections.
Bloom time
Michaelmas daisies flower from August to October, often peaking around September. In mild southern gardens, late varieties may continue into November; in cooler northern areas they begin and finish a little earlier. Their late flowers provide important colour and nectar when many other perennials have finished.
Garden uses
Grow asters through sunny borders, meadow-style schemes and cut-flower patches, combining them with sedums, rudbeckias and grasses. Use shorter cultivars near the front or in large containers. Their open centres are excellent for bees and butterflies, making asters a valuable component of RHS Plants for Pollinators planting.
Tips
Choose mildew-resistant varieties and give every plant good airflow. Avoid drought stress, which can worsen powdery mildew, but do not overwater foliage. Dividing clumps regularly keeps them youthful and floriferous. Seek AGM selections through the RHS or a local garden centre, especially where autumn colour is a priority.
Growing Aster (Michaelmas Daisy): frequently asked questions
How do I grow aster (michaelmas daisy) in the UK?
Plant asters in April or May, after the last spring frost, or in early autumn where winters are milder.
When does aster (michaelmas daisy) flower?
Michaelmas daisies flower from August to October, often peaking around September.
How do I care for aster (michaelmas daisy)?
Mulch in spring to retain moisture, water during dry spells and stake taller cultivars before they flop.
General guidance for UK gardens. Timing and hardiness vary by region and season; the RHS or a local garden centre can advise for your area. Page updated 18 Sep 2026.