Soil: Sand to loam
Light: Full sun to part sun
Bloom colour: White with yellow centre
Bloom period: Mid-summer to frost
Height: 3 - 5 feet/100 - 150 cm
Moisture: Medium to wet
Attracts: A large range of pollinators
Notes: Flat-topped white aster is native to eastern and central U.S.A and Canada. There are lots of white Asters in N. America but this is one of my favourites. A lot of white Asters can look a bit weedy and have to be planted en-masse. Flat-topped white aster can look absolutely majestic and you get all the wildlife benefits as well. The distinctive features of this Aster are its flat topped inflorences made of up decent sized composite flowerheads as well as the stiff and firm textured leaves. As the flowers on the central disc mature, the colouration will turn from yellow to cream. The blooms will persist for several weeks after they lose their appeal to pollinators. A single specimen of this plant can look quite good when placed appropriately in the garden.
The main reason for putting this plant in a wildlife garden is that it blooms earlier than other asters at a time when there are many different pollinators around to take advantage of the pollen and the nectar that it offers in accessible flowers. It is a standout plant for attracting a range of beneficial wasps as all the accompanying pictures verify. It is also a host plant for the Harris Checkerspot and Pearly Crescent butterflies.
Flat-topped white aster occurs on the edge of wetlands but they will thrive in average garden conditions in a soil with reasonable drainage and regular watering.
Flat topped aster works very well in the middle or at the back of a late summer border. The tall and stiff stems also make this plant a good candidate for growing in the centre or at the back of large containers.Since the bloom occurs at the top of the plant, the flowers will be highly noticeable even when grown behind other similar sized plants.