Autumn means asters to most gardeners and that usually refers to perennial asters – real asters (or they used to be till they were renamed as symphyotrichum). But late summer is also the season of annual asters or, more properly, callistephus – unless those meddling botanists have been at work here too!
As bedding plants they are a bit lacking because they do not bloom till quite late and they have a finite number of buds so you do not get a long display of blooms. But their flowers are lovely and they make excellent and long lived cut flowers.
Apart from ignoring the dwarf ‘bedding types’, it is difficult to chose a favourite though I always love the single ‘super chinensis’ types with their bright, yellow centres.
And of the doubles, I prefer the needle-petalled types that open into large ‘fibre optic’ blooms, such as T&M’s ‘Spider Chrysanthemum Mixed’ or ‘Unicum’.
These asters are grown as half hardy annuals. I sow the seeds in mid to late March in seed trays in gentle heat (20c). The seedlings are transplanted into small cell trays and grown on in the greenhouse and put outside to harden off in early May, making sure they are not frosted. The seedlings are planted out in late May and spacing varies but they need at least 20cm to give them room to grow. They require full sun to bloom well and apart from a soil disease that you may never experience, the only real pest is aphids.