Sow the seed thinly 13mm (½") deep direct into finely raked, moist, warm, weed free soil where the plants are to flower. Germination usually takes 10-15 days. As the seedlings develop, thin them out gradually to achieve a final spacing of 30cm (12"). For early flowering sow in trays indoors in February-March, transfer into 9cm pots, grow on then acclimatise before planting outside where the plants are to flower, once the risk of frosts have disappeared.