Cosmos / RHS Plant Guide

Cosmos

RHS Genus Guide

Both the perennial Cosmos atrosanguineus and the annual cosmos are upright plants, making excellent additions to a summer border. The annuals are particularly effective when massed and provide flowers for cutting over a period of months. Annual comos are easily grown from seed.

Botanical name: Cosmos

RHS / Joanna Kossak

Appearance

Annuals have feathery leaves and saucer-like, white, pink, red, orange or yellow flowers. In some, the petals fuse to form an open cup. Cosmos atrosanguineus has dark red, chocolate-scented flowers.

Preferences

Cosmos grow in most ordinary garden soils, provided they aren't soggy in summer, in full sun.

Dislikes

Very dry, poor soils and heavy, wet soils are unsuitable. Plants will not flower in shade.

Did you know?

Cosmos atrosanguineus is not reliably hardy. To ensure its survival over winter, cover the base of the plant with 15cm (6in) layer of straw or other dry material.

RHS Growing Guide