Sow early spring to early summer outdoors where they are to flower. Prepare the ground well and rake to a fine tilth before sowing, but do not exclude light, which is beneficial to germination. Sow 6mm (0.25in) deep in rows 30cm (12in) apart.
When large enough to handle thin out to 8cm (3in) apart. They prefer a sunny open site but will grow in most sites and soils.