Sow outdoors, March-May, where they are to flower, 0.5cm (Â¼") deep, directly into finely-prepared, well-drained soil, which has already been watered. Seedlings usually appear in 14-28 days. Thin them to 30cm (1') apart. Water well until plants are established. Or sow indoors, March-May, in trays of compost. Water well and place in a cold frame or greenhouse. Keep moist. Transplant seedlings, 5cm (2") apart, to other trays when large enough to handle (always hold by a leaf, never by the stem). Gradually accustom young plants to outside conditions (avoid frosts), before planting out, May-June, 30cm (1') apart, when frosts are over. Flowers: June-October.