Cosmos are half-hardy annuals with daisy-like flowers that are easy to grow from seed and are incredibly long flowering, from midsummer until the first frosts.
They’re very useful for filling gaps in summer borders, look good in meadow-style planting schemes and are ideal for container displays. They make fantastic cut flowers and are great for wildlife, too – they attract bees, butterflies and hoverflies.
Discover 10 colourful cosmos to grow.
For the best results, sow seeds in March or April. Harden off the seedlings before planting out in a sunny spot, and deadhead the spent blooms regularly to prolong flowering.
Cosmos look good with many different plants – here are eight inspirational combinations.
Cosmos and calendula
Here, the magenta Cosmos bipannatus ‘Dazzler’ is grown in drifts, combined with a tall marigold, Calendula officinalis ‘Indian Prince’. Both are easy to grow from seed and make excellent cut flowers.
Cosmos and zinnia
In this all-pink combination, the daisy-like flowers of pale pink cosmos are enhanced by magenta zinnias. Discover eight essential border daisies to grow.
Cosmos and tobacco plant
White cosmos and tobacco plant (Nicotiana) are two essential components of a white garden. If you mostly enjoy your garden in the evening after work, white plants work really well as they show up well in the fading light. Discover how to grow nicotiana from seed.
Cosmos and dahlias
Cosmos and dahlias both bring colour and long-lasting blooms to gaps in borders, and both are staples of the cutting patch. As their flower forms can be quite similar, grow contrasting colours. Browse our plant database for over 70 beautiful dahlias to grow.
Cosmos, thalictrum, nepeta and hardy geranium
In this blue and white display, annuals and perennials combine – the white cosmos is combined with the spray like white flowers of Thalictrum delavayi ‘Album’, and the blue flowers of catnip (Nepeta racemosa ‘Walkers Low’) and Geranium ‘Orion’.
Cosmos, French marigold and bidens
Orange and white is quite an unusual flower combination – the yellow/orange centre of the cosmos complements the orange of the double flowers of French marigold (Tagetes) and tickseed (Bidens).
Cosmos and eryngium
Cosmos bipinnatus ‘Antiquity’ has flowers that start off crimson, then fade slightly. They contrast with the icy blue, spiky flowers of Eryngium x zabelii ‘Big Blue’.
Cosmos and Verbena bonariensis
Cosmos look great in meadow-style planting schemes. Here they are paired with airy Verbena bonariensis. Both plants will flower for months on end.