Cosmos in Barns of Claverhouse
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 Feb – 21 MarSow seeds in trays or modules from 25th February to 21st March, using of fine compost. Keep them at and just moist, not wet.
Prick Out Seedlings
23 Mar – 6 AprMove seedlings on when they are large enough to handle, from 23rd March to 6th April. Pot them into small pots and keep them growing in a bright, frost-free place.
Harden Off Plants
28 Mar – 11 AprAcclimatise plants over 15 days before planting out, from 28th March to 11th April. 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
25 Apr – 12 MayPlant into free-draining soil from 25th April to 12th May, spacing plants apart. Water in thoroughly straight after planting and protect young plants from slugs and late cold snaps if needed.
Deadhead & Maintenance
2 Jun – 12 OctRemove fading flowers regularly from 2nd June to 12th October. 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 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.