Sow the seed thinly direct into finely raked, moist, warm, weed-free soil where the plants are to flower 13mm (½") deep. Germination takes 10-14 days. As the seedlings develop, thin to achieve a final spacing of 30cm (12"). Alternatively, for pots and patio containers sow on a windowsill or in a greenhouse at approximately 13-18°C (55-65°F), 3 or 4 seeds to a 7.5cm (3") pot. Plant out after careful acclimatisation to outside conditions.