Cosmos in Bearsbridge
Cosmos bipinnatus
A half-hardy annual grown for long-lasting, daisy-like flowers. In the UK it does best in a sunny, sheltered spot with free-draining soil, and it flowers freely from summer into autumn if you keep it deadheaded.
Growing Guide
Step-by-step instructions for growing Cosmos
Planting Calendar
Sow Seeds Indoors
25 Mar – 18 AprSow seeds in trays or modules from 25th March to 18th April, using of fine compost. Keep them at and just moist, not wet.
Prick Out Seedlings
20 Apr – 4 MayMove seedlings on when they are large enough to handle, from 20th April to 4th May. Pot them into small pots and keep them growing in a bright, frost-free place.
Harden Off Plants
25 Apr – 9 MayAcclimatise plants over 15 days before planting out, from 25th April to 9th May. Put them outside in the daytime at first, then leave them out for longer each day so they do not check in cold weather.
Plant Out
23 May – 9 JunPlant into free-draining soil from 23rd May to 9th June, spacing plants apart. Water in thoroughly straight after planting and protect young plants from slugs and late cold snaps if needed.
Deadhead & Maintenance
30 Jun – 28 SeptRemove fading flowers regularly from 30th June to 28th September. This stops the plant setting seed too early and keeps it producing flowers until the autumn frosts. Tie in taller stems if the plants get blown about, and water during dry spells.
Companion Plants
Tap a plant to see why it works (or doesn't) with Cosmos.
Good companions
Plants to avoid
Why companion planting matters
Companion planting can deter pests, improve pollination, and make better use of space. Some plants confuse pests or attract beneficial insects; others improve soil or offer shade to neighbours that need it.
Suggested Varieties
Popular varieties of Cosmos to consider
Sensation Mixed
Tall, open plants with large single flowers in mixed colours. A very common bedding and cutting strain in UK catalogues.
Purity
Tall white-flowered plants with good stems for cutting. Reliable in a sunny border.
Sea Shells Mixed
Distinctive tubular petals and strong colour range. Good for a lighter, airy planting effect.
Sonata White
A shorter, compact type suited to pots and front-of-border planting. Useful where space is limited.
Related Plants
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Basil
Basil is a fragrant, tender herb whose leaves are a staple of summer cooking. Native to tropical regions, basil is treated as an annual in temperate climates like the UK because it cannot tolerate frost. It thrives in warm, sunny conditions and can be grown in garden beds or pots for a steady supply of fresh, flavourful leaves throughout the summer.
Brussels Sprouts
Brussels sprouts are a hardy winter brassica (cabbage family) that form sturdy, leafy stems often around 60–90cm tall. They produce edible mini-cabbage buds along the stem from autumn through winter. Thanks to their cold tolerance, sprouts remain productive into late winter, and frost actually improves their sweetness.
Calabrese
Calabrese (broccoli) produces a large central head of tightly-packed green buds, followed by smaller side-shoots after the main head is cut. It’s a cool-season brassica crop. Grow it in full sun with fertile, well-drained soil and keep plants watered during dry spells. Harvest the heads while firm, then leave the stem in the ground to allow side-shoots to develop.