How to Sow and Grow Kohlrabi: A Complete Guide
Kohlrabi is a quick brassica grown for its crisp swollen stem. It fits between slower crops, succeeds in beds and containers, and can be harvested from spring to autumn. The best bulbs come from steady growth; drought or delayed harvesting makes them woody.
Choosing varieties
Green and purple kohlrabi taste similar. Early compact varieties mature quickly, while giant storage types need more time and space but can remain tender at a larger size. Choose bolt-resistant cultivars for early sowing and heat-tolerant ones for summer.
When to sow
Sow under cover from late winter for early planting, then make direct or module sowings every three to four weeks from spring to midsummer. In hot climates, concentrate on spring and autumn. Avoid large sowings because bulbs mature together.
How to sow
Sow 1 cm deep in modules or drills. Keep around 15–20°C until germination and provide bright conditions. Thin modules to one plant and direct rows promptly. Transplant before roots become congested and keep the swollen stem above soil level.
Spacing and containers
Space small varieties 20–25 cm apart in rows 30 cm apart; larger cultivars need 30–45 cm. Kohlrabi grows well in containers at least 20 cm deep, with plants spaced so leaves can develop without crowding.
Soil, water and feeding
Use fertile moisture-retentive soil enriched with mature compost. Water regularly because interrupted growth produces tough stems and splitting. A balanced organic feed is useful on poor soil or in containers, but excessive nitrogen produces leaves rather than bulbs.
Pest protection
Fine insect-proof mesh protects young plants from flea beetles, cabbage butterflies and birds. Secure the edges and support mesh clear of leaves. Check for slugs around the base.
Common problems
Woody bulbs: harvest younger and prevent drought or overcrowding
Splitting: keep soil moisture steady after dry weather
Flea beetles: cover seedlings immediately with fine mesh
Clubroot: rotate brassicas and improve drainage
Bolting: use seasonal varieties and avoid checks from cold or drought
Harvesting and storing
Pull or cut kohlrabi when ordinary varieties reach roughly tennis-ball size, unless the cultivar is bred to grow larger. Remove roots and leaves; young leaves are edible. Bulbs keep for several weeks refrigerated, while suitable storage varieties last longer in cool humid conditions.
A reliable approach
Sow small batches, transplant young, keep roots moist and harvest before stems become oversized. Kohlrabi is most useful as a rapid succession crop rather than one large planting.
