When to plant Cosmos in Bristol

Sow seeds in trays or modules from 5th March to 29th March, using 0.5 cm of fine compost. Keep them at 18–21 °C and just moist, not wet.

Move seedlings on when they are large enough to handle, from 19th March to 26th April. Pot them into small pots and keep them growing in a bright, frost-free place.

Acclimatise plants over 15 days before planting out, from 19th April to 3rd 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 into free-draining soil from 3rd May to 20th May, spacing plants 30 cm apart. Water in thoroughly straight after planting and protect young plants from slugs and late cold snaps if needed.

Remove fading flowers regularly from 2nd June to 2nd November. 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.