Growing New England aster 'Purple Dome' in a pot

Water regularly during spring and summer, particularly in dry spells. Aster 'Purple Dome' has moderate water needs and performs best when the soil remains consistently moist but not waterlogged. In clay or loam soils with good organic matter, weekly deep watering is usually sufficient; in lighter soils or during hot weather, increase frequency. Reduce watering in autumn as growth slows and rainfall typically increases. Feed in April or May as new growth appears. Apply a balanced general-purpose granular fertiliser such as Growmore or blood, fish and bone around the base at the rate recommended on the packet, then water in. A second, lighter feed in early summer can boost flowering, but avoid high-nitrogen fertilisers after June, as these promote soft, leafy growth at the expense of flowers and increase susceptibility to mildew. Powdery mildew is the most common problem, especially in dry conditions or where air circulation is poor. White, powdery patches appear on leaves in late summer. Good spacing, mulching to retain soil moisture, and watering at the base rather than overhead all help prevent it. Affected plants usually recover without intervention. Slugs and snails may damage emerging shoots in spring; use your preferred control method if damage is severe. Refresh the mulch layer each spring with garden compost or well-rotted manure to suppress weeds, retain moisture and provide a slow-release nutrient boost. Aster 'Purple Dome' is fully hardy and needs no winter protection in zones 7–9. Clumps benefit from division every three to four years in spring to maintain vigour and flowering quality.