Cosmos in Fortuneswell

Cosmos bipinnatus

Cosmos
Cosmos · 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.

90 cm · Full Sun · Moderate Water

Add to garden

Calibrated to Fortuneswell · last frost ≈ 20 Mar

Sow indoors February, plant out April. Frost risk December to March.
ActivityJanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecember
Sow indoorsNoYesNoNoNoNoNoNoNoNoNoNo
Plant outNoNoNoYesNoNoNoNoNoNoNoNo

Growing guide

Step-by-step instructions for growing Cosmos

  1. 01

    Sow Seeds Indoors

    3 Feb to 27 Feb

    Sow seeds in trays or modules from 3rd February to 27th February, using of fine compost. Keep them at and just moist, not wet.

  2. 02

    Prick Out Seedlings

    1 Mar to 15 Mar

    Move seedlings on when they are large enough to handle, from 1st March to 15th March. Pot them into small pots and keep them growing in a bright, frost-free place.

  3. 03

    Harden Off Plants

    6 Mar to 20 Mar

    Acclimatise plants over 15 days before planting out, from 6th March to 20th March. Put them outside in the daytime at first, then leave them out for longer each day so they do not check in cold weather.

  4. 04

    Plant Out

    3 Apr to 20 Apr

    Plant into free-draining soil from 3rd April to 20th April, spacing plants apart. Water in thoroughly straight after planting and protect young plants from slugs and late cold snaps if needed.

  5. 05

    Deadhead & Maintenance

    11 May to 4 Dec

    Remove fading flowers regularly from 11th May to 4th December. 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.

Cosmos guides by town

See how Cosmos timing shifts in other towns with different frost dates.