Aster novi-belgii Dauerblau

The 'Dauerblau' New York Aster is a large recent variety with blue-purple flowers in September-October. Autumn wouldn't be the same season of colours without these perennials covered in their bright blue-violet stars. Rugged and easy to grow, this aster thrives in mediocre soil as long as it remains moist.

The 'Dauerblau' New York Aster belongs to the Asteraceae family. This hybrid originated from the Aster novi-belgii and is found along the east coast of North America, ranging from Newfoundland to Georgia. This perennial exhibits an upright, bushy habit from the start of spring. It reaches 1.40m (5ft) in height when in bloom, and spreads up to 1m (3ft) in width. The very generous flowering takes place in September and October. The inflorescence takes the form of a capitule with ligulate peripheral flowers that are blue-purple. The central flowers (the heart) are yellow-orange. This aster is a deciduous perennial with smooth, branching stems. The leaves are smooth and dense, sessile, lanceolate, and medium green. They measure 8-16 cm (3-6in) long and 3.5 cm (1in) wide, with rough edges and a dentate upper half.

Plant the 'Dauerblau' New York Aster in autumn or spring in ordinary, rich, and well-worked soil that retains moisture. It prefers a sunny exposure but tolerates partial shade, where it will have a slightly looser habit. Strong winds should be avoided as they may flatten the clumps. Once established it is best not to move it as it does not like change. In a flowerbed allow at least 50 cm (20in) spacing around the plant. Mulch the soil from June onwards and water in case of heatwaves. New York Asters are susceptible to powdery mildew, which manifests as a white powdery coating on the leaves. Spray preventively with Bordeaux mixture or another copper-based product. Divide the clumps every three years to ensure they remain floriferous and more resistant to disease. Do not replant the divisions in the same spot, and provide them with rich soil.

It is impossible to imagine gardens without aster beds or borders. Undemanding, they pair well with all other plants in the garden, such as Salvia microphylla or Crocosmia 'Meteore'. Both cheerful and melancholic, these perennials are a fixture of the autumn season and accompany the splendour of its foliage. Try combining blue asters with the 'Grace' Smokebush or dwarf winged euonymus: the colour combination is stunning. These plants also make excellent cut flowers.

In Europe cultivars bloom around the month of October - the month of harvest - which earned the species the name 'grape harvester'. The 'Dauerblau' New York Aster (Symphyotrichum novi-belgii) is sometimes called "Virginia aster," but scientifically speaking, this species is no longer classified within the genus Aster by many experts.