Expe choice Cosmos bipinnatus
Whatever the variety, and there’s a dizzying range, these are all very easy to grow, says Graham Rice
Each flower is crowded with cranberryred petals rolled into frilly tubes, often hiding the yellow eye. 1.1m x 45cm
They’re like big daisies, right? Well, yes and no. Wild Cosmos bipinnatus from Arizona and Central America is tall, up to 2m in height, its divided leaves cut into thread-like leaflets and big yellow-eyed daisy flowers with white or pink petals.
After it arrived in Britain from Mexico in 1799, the seed companies started reducing the height to a metre or a little more, separating the flower colours and bringing forward the flowering time from late to early summer. A hundred years later there were double flowered varieties. Then it took another hundred years for ‘Sonata White’, just 60cm tall, to make cosmos suitable for the smallest gardens.
The last thirty years have brought new colours, at least three different kinds of bicolours, three kinds of double-flowered varieties and new flower shapes. The latest innovation is the lovely Cupcakes Series, originating in a private garden in California, in which the petals are fused into an elegant bowl.
But the elegantly simple single-flowered types retain their appeal, with traditional colours, antique shades and peachy bicolours, mixed with prolific flowering. And the one thing that has remained constant all this time is that they’re easy to grow. You can even sow them now for autumn flowering.
Happy in any reasonable soil in full sun, though avoid extremes of drought and waterlogging.
Sow seeds inside in March or April, outside in May or even in June or July for later flowering.
Frost tender, so only plant them out after the last frosts in your area.
Taller varieties will usually need support, a single cane supporting the main stem is often enough.
Regular picking or deadheading will keep the flowers coming into autumn.
Where to buy mr-fothergills.co.uk, 0333 777 3936; nickys-nursery.co.uk, 01843 600972; thompson-morgan.com, 0333 400 0033.