Sow indoors, February-April, in pots or trays of seed compost. Maintain gentle warmth (21-24C) and keep the compost moist, but not saturated. Germination usually takes 5-14 days. Thin (prick out) to other trays when large enough to handle. Harden off before planting out, late May, allowing 23cm (9″) between plants. Or outdoors, April-May, in flowering position. Thin seedlings if necessary. Flowers: June to October. Remove dead heads to prolong the flowering season.