Sow seed on the surface of a good free-draining, damp seed compost. Cover with a very fine sprinkling of compost or vermiculite. Place in a propagator or seal container inside a polythene bag and place at 20-25°C (68-77°F) until after germination which usually takes 7-21 days. Do not exclude light as this helps germination.
Transplant seedlings into trays or 7.5cm (3in) pots once large enough to handle. Grow on in cooler conditions for 10-15 days before planting out 15-20cm (6-8in) apart after all risk of frost has passed.