Sow seeds late winter to early spring at 21C (70F) in a good free draining seed compost. Sow seeds on surface of compost and do not exclude light, sealing in a polythene bag after sowing is helpful. Germination usually takes 14-30 days. They can also be sown direct in mid spring in well raked soil and thinned out to 15cm (6 inch) apart.
When seedlings are large enough to handle, transplant and grow on in cooler conditions. Gradually acclimatise to outdoor conditions for 10-15 days before planting out after all risk of frost 15cm (6in) apart in ordinary well drained soil.