Sow in a propagator on a windowsill, or in pots or trays in a greenhouse, at approximately 15-20°C (60-68°F) using a good quality, moist seed compost. Cover the seeds with 3mm (1/8") sieved compost. Germination 10-21 days. Transfer resulting seedlings, spacing them 5cm (2") apart in trays and grow on. Acclimatise plants to outside conditions before planting out 23cm (9") apart when danger of frost has passed. May also be sown direct outside late April/May. Can also be sown in September to overwinter under glass for early flowering the following year.