March–May, only for a suitable harvest typeSow somewhere cool and bright and avoid long, weak growth.
- Germination and temperature
- Germinate under cover, then grow on in cool, bright, well-ventilated conditions; avoid a hot growing space.
- After emergence
- Give seedlings light immediately after emergence. A dark loft needs suitable grow lights; warmth alone is insufficient. Ventilate and keep the compost moist without saturating it.
- Pricking out and potting on
- Sow in modules or prick out manageable young plants. Let the root ball firm up without a check in growth.
- Hardening off and planting out
- Gradually acclimatise indoor-raised plants to sun, wind and outdoor temperatures; shelter them again on cold nights. Plant out sturdy young brassicas and protect against cabbage root fly and caterpillars where needed.
Early, summer, autumn and winter cultivars have their own windows. The spring period shown is a basic route; use cultivar guidance for overwintering and winter cauliflower.
Sources and use
Royal Horticultural Society · RHS — kool kweken ↗Soort- of productgebonden bron; buitenlandse perioden zijn geen vaste Nederlandse zaaidatum.
University of Minnesota Extension · UMN Extension — kool in de moestuin ↗Soort- of productgebonden bron; buitenlandse perioden zijn geen vaste Nederlandse zaaidatum.
Guideline periods for the Netherlands and Flanders. Check the variety, available light, soil and measured temperatures. Greenhouse heating does not guarantee enough winter light.