Cosmos: when to sow, plant and see it flower
Sowing, planting and flowering dates for your climate, with growing advice.
Photo: JA2020, Pixabay Content License · image resized
When to sow and plant in your region
Average dates, computed from the frost dates of each climate. For your exact dates, choose your town.
| Climate | Sow under cover | Sow outdoors | Plant out | Flowering |
|---|---|---|---|---|
| South and east of England | 23 February – 21 April | 20 May – 17 June | 20 May – 17 June | 9 July – 3 November |
| South-west England and Wales | 12 February – 10 April | 22 May – 19 June | 22 May – 19 June | 11 July – 19 November |
| Midlands, northern England and Northern Ireland | 6 March – 2 May | 1 June – 29 June | 1 June – 29 June | 21 July – 28 October |
| Scotland | 16 March – 12 May | 13 June – 11 July | 13 June – 11 July | 2 August – 19 October |
| Ireland | 20 February – 18 April | 1 June – 29 June | 1 June – 29 June | 21 July – 10 November |
Growing
- Life cycle
- Annual (sown and in flower the same year)
- Family
- Asteraceae
- Latin name
- Cosmos bipinnatus
- Cold tolerance
- Tender (killed by frost)
- Soil temperature to germinate
- 16 °C minimum
- Emergence
- 7–10 days
- Spacing
- 30 cm
- From sowing to flowering
- 50–90 days
Sources
- Jardiner Malin — Associations de légumes et fruits au potager
- Terre Vivante — Associer légumes et plantes pour protéger le potager
- The Old Farmer's Almanac — Vegetable growing guides (garlic, shallots, onions, spinach, peas, lettuce, kale, radishes, carrots, beets, swiss chard, kohlrabi, bok choy, fennel, cabbage, mustard greens, rutabagas, rhubarb, mint, cilantro, corn, arugula)
- NC State Extension Gardener Handbook — 10. Herbaceous Ornamentals
- RHS — Plant pages (hardiness ratings H1-H7)
- Gerbeaud — flower and bulb fiches (cosmos, souci, capucine, tournesol, alysse, zinnia, nigelle de Damas, coquelicot, pavot de Californie, pois de senteur, muflier, reine-marguerite, ipomée, mauve annuelle, annuelles rustiques, giroflée ravenelle, digitale, myosotis, pensée, rose trémière, pâquerette, lupin, ancolie, delphinium, échinacée, rudbeckia, gaillarde, achillée, tulipe, crocus, jacinthe, perce-neige, muscari, ail d'ornement, dahlia, glaïeul, lis, bulbes d'automne, profondeur de plantation)
- Jardiner Malin — flower and bulb fiches (same species; the lin, bleuet and lavatère pages are seed product pages, and lin is red flax)
- Plantura — flower portraits and planting guides (Cosmea, Kornblume, Jungfer im Grünen, Mohnblume, Flachs, Goldlack, Vergissmeinnicht, Stockrose, Silberblatt, Bartnelke, Kokardenblume, Rittersporn, Akelei, Sonnenhut, Blumenzwiebeln, Tulpen, Gladiolen)
- Royal Horticultural Society — growing guides (annuals and biennials: sowing in spring, sowing in autumn; sunflower, sweet pea, zinnia, lavatera, foxglove, lupin, hollyhock, delphinium, aquilegia, rudbeckia, achillea, tulip, daffodil, crocus, hyacinth, snowdrop, allium, dahlia, gladioli, lily, bulbs)
- The Old Farmer's Almanac — flower growing guides (cosmos, calendula, marigolds, nasturtiums, sunflowers, sweet alyssum, zinnias, sweet peas, snapdragons, morning glories, poppies, bachelor's buttons, foxglove, pansies, hollyhocks, lupines, columbine, delphiniums, coneflowers, black-eyed Susans, yarrow, dianthus, tulips, daffodils, crocuses, hyacinths, snowdrops, dahlias, gladiolus, lilies)
- Johnny's Selected Seeds — Flower Growing Guide and key growing information pages
- Promesse de Fleurs — advice pages (jacinthe read in full; the others through search-result summaries only, the pages return their navigation shell)