Plant easy-to-grow cosmos seeds for annuals with spectacular summer flowers. Perfect for borders and cottage gardens, sow single, semi-double, double, or fluted varieties and prepare to enjoy a floral display that packs a real punch. Available in a broad spectrum of colours, cosmos flowers are never anything other than bright, colourful, and vibrant, which is why they're a big hit with bees and other pollinators as well as people. Growing cosmos for the first time? Make sure you deadhead regularly to keep the blooms coming.
Cosmos are the perfect summer border filler, and make lovely cut flowers too. Sow them under cover in late spring or direct sow into the border after the last frosts.
If you’re growing a taller variety such as a bipinnatus, choose a sheltered spot out of the wind or stake plants with a support cane. In a cut flower border, grow them through pea netting.
Cosmos are grown as annuals in the UK as they are not frost-hardy. However, they will self-seed, so if you leave them to their own devices they’ll grow again in the same spot in following years.
Cosmos will usually take between seven and 21 days to germinate, going on to flower around six weeks later. A warm environment will encourage faster germination.
Cosmos plants vary in height from dwarf varieties, such as ‘Dwarf Purple Picotee’, which grows to 30cm (12ins), through to tall varieties such as ‘Cupcakes White’, which can reach 120cm (47.2ins).
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