Thompson & Morgan Kew 'Cosmos' seeds

Part of the Kew Pollinators seed range, developed alongside the Royal Botanic Gardens, Kew, Cosmos brings tall, ferny foliage and bright single blooms in shades ranging from glacial white through to carmine pink, giving a cheery splash of colour to the back of borders. It mingles beautifully with summer-flowering perennials, and thanks to its strong stems and good vase life, it's a lovely choice for cutting — though pollinating insects will thank you for leaving some flowers in the border, where they're a valuable source of nectar right through summer. Quick and easy to grow, Cosmos bipinnatus more or less looks after itself once established, making it a great option for anyone after reliable colour without much fuss.

Growing guide

Sow from March to May, at a depth of around 3mm, into good-quality seed compost, covering with a fine sprinkling of vermiculite. Place in a propagator at 18–25°C, or seal inside a polythene bag, until germination. Once seedlings are large enough to handle, transplant and grow on in cooler conditions before planting out once all risk of frost has passed. Plants reach up to 120cm tall with a 60cm spread, so give them a little room and a spot towards the back of the border. Cosmos performs best in average to poor soil in full sun — resist the urge to feed it, as overly rich soil tends to produce more leaf and fewer flowers.