In autumn, surface-sow on moist compost in small pots or seed trays and keep them in a greenhouse or cold frame at 15-20°C (59-68°F). Germination can be slow (up to 3 months) but seedlings should be thinned out as they grow on and over-wintered under glass before planting out after hardening off in spring. Alternatively, spring sowing can be undertaken as before, often without the need for heat.
Alternatively, spring sowing can be undertaken as before, often without the need for heat.