Cosmos

New and recent introductions make colourful cosmos as brilliant in the garden as it is in the vase.

- Graham Rice

For too long, annuals have been looked down upon by some gardeners as not in the same league as perennials. “Oh, it’s just an annual,” people say dismissively. Well, last summer’s display of almost 90 annual cosmos at the RHS Garden at Wisley made it clear what valuable plants they are.

There are about 30 species of cosmos, annuals and perennials, growing wild across subtropical America, and in Mexico in particular; two species extend their range into southern USA. The familiar garden cosmos, C. bipinnatus, grows naturally in rough meadows and scrub in Mexico, but has also established itself farther afield including much of southern and eastern USA as well as South Africa and Australia.

The only other cosmos species widely grown is the perennial C. sulphureus, with orange or yellow flowers, usually grown as an annual, and the popular tuberous perennial C. atrosanguineus, with its chocolate coloured and chocolate-scented daisies.

C. bipinnatus is a vigorous annual reaching from 60cm to 3m or more, with stout upright stems carrying large, attractive, fresh-green foliage repeatedly divided into thread-like segments. From midsummer into autumn, large golden centred daisies open in a wide range of pink and rich-red shades with white. Last year saw the introduction of the first effective yellow-flowered variants.