How to Grow Italian Aster
Aster amellus
Aster amellus is a compact, drought-tolerant European perennial with violet-blue daisy flowers and golden centres from August to October. Unlike New World asters, it prefers alkaline, well-drained soil and full sun, and is naturally resistant to powdery mildew. Cut back to a few centimetres after flowering. Divide clumps every 3-4 years in spring to maintain vigour. Does not need staking when grown in full sun.
Yearly Lifecycle
Care Essentials
Apply a balanced granular fertiliser in spring as new growth emerges. A light top-dressing of general-purpose feed in May is sufficient — avoid high-nitrogen feeds which promote leafy growth at the expense of flowers.
Watch For
- Aphids
- Aster yellows (phytoplasma)
- Powdery mildew (rare on this species)
- Slugs on young growth
Companions
Rudbeckia, Sedum (Hylotelephium), Ornamental grasses, Echinacea, Salvia nemorosa
Care Requirements
Light
Full sun essential
Requires at least 6 hours of direct sun daily. In shade, plants become lax and flower poorly.
Watering
Drought tolerant once established; water sparingly
Water young plants regularly to establish. Once established, Aster amellus is drought tolerant and prefers drier conditions than Symphyotrichum asters. Avoid waterlogging, especially in winter.
Fertilizing
Light spring feed; avoid high nitrogen
A single application of balanced granular fertiliser in spring is sufficient. High-nitrogen feeds produce leafy growth at the expense of flowers. No need to feed through summer.
Soil
Well-drained, alkaline to neutral soil
Thrives in chalk or limestone soils. On heavy clay, improve drainage with horticultural grit or plant on a raised bed. Avoid acid soils.
Pruning
May pinch; cut back after flowering
Pinch shoot tips by one-third in late May for compact bushy growth. Remove spent flowers to prolong the display. Cut all stems to 5-10 cm after flowering in autumn.
Growing Tips
Soil drainage is the key
Aster amellus resents wet roots, especially in winter. On heavy soils, plant on a slight mound or improve drainage with grit. Alkaline to neutral pH gives the best performance.
May pinch for compact growth
In late May, cut the young shoots back by one-third. This produces a shorter, bushier plant with significantly more flowers in late summer — no staking needed.
Deadhead to extend the show
Remove spent flowerheads as they fade. This encourages more buds to open and can extend the flowering season by several weeks into October.
Divide every 3-4 years
Unlike Symphyotrichum asters, Aster amellus doesn't need annual division. Lift and divide congested clumps in spring every 3-4 years, replanting only the vigorous outer portions.
Pests & Diseases
Pest Aphids
Identification: Clusters of small green insects on shoot tips and buds, causing distorted growth
- Squash by hand or blast off with a water jet
- Encourage ladybirds and lacewings
- Spray with a contact insecticide containing deltamethrin
Pest Slugs and Snails
Identification: Irregular holes in young leaves and shoots; slime trails on and around plants
- Apply organic slug pellets (ferric phosphate) around emerging shoots
- Use beer traps or copper tape barriers
- Ferric phosphate-based pellets
Disease Aster Yellows
Symptoms: Yellow, stunted growth; deformed flowers; green petals (virescence). Caused by phytoplasma transmitted by leafhoppers
Treatment: No cure. Remove and destroy affected plants immediately. Do not compost
Prevention: Control leafhopper populations; remove weeds that act as host reservoirs
Disease Powdery Mildew
Symptoms: White powdery coating on leaves — much less common on Aster amellus than on Symphyotrichum
Treatment: Remove affected leaves. Spray with a fungicide approved for ornamentals if severe
Prevention: Ensure good air circulation and avoid drought stress. This species is naturally resistant
