Annual Pollinator

Cosmos Purity

Cosmos bipinnatus 'Purity' — the definitive white Cosmos

£2.40approx. 100 seeds

Pristine silky white petals around a small golden disc — the definitive white Cosmos for cutting, weddings and the moon garden. Glows in evening light.

Sowing months
JanFebMarAprMayJunJulAugSepOctNovDec
Height
90–120cm
Spread
50cm
Spacing
45cm
Position
Full sun
Soil
Poor, lean, UNFED soil only — the most important rule for all Cosmos
Grow guide
How to grow Cosmos Purity
Read the full guide →
About this variety

Broad silky white petals around a small gold disc, 8 to 10cm across, on airy stems at 90 to 120cm. If you grow one white flower for cutting, this is a strong candidate.

White is the most useful colour in a bouquet because it makes everything beside it read more strongly. A jug of mixed cottage flowers with 'Purity' through it looks brighter than the same jug without. It also glows at dusk in a way coloured flowers do not, which is why it turns up in every moon garden and every evening border.

The drawbacks are the ones that come with white. Rain spots the petals brown and they stay spotted, so cut ahead of a downpour if you have a use in mind. And it self-seeds enthusiastically. Volunteers will come up for years and gradually drift back towards pink, so pull anything that is not white if you want the planting to stay clean. It is half-hardy, flowering July to the frosts, and it wants lean ground. Feed it and you get a six-foot green shrub with a dozen flowers on it.

Plant alongside

Cosmos Purity pairs beautifully with these cottage garden classics

RHS Plants for Pollinators

This plant has been assessed by the Royal Horticultural Society and recommended as especially beneficial to bees, butterflies and other pollinators. Growing plants like this directly supports UK pollinator populations — something close to our hearts at Salle Moor Hall Farm, where we see the difference a cottage garden full of the right plants can make.

Learn more at RHS.org.uk →