Kohlrabi is a tasty brassica that is easy to grow, even though it is not widely available in the UK. It can thrive in poor soil and has a flavour similar to a combination of cabbage and turnip. The skin gives this vegetable a nutty taste, and it comes in purple, white and green varieties.
Kohlrabi can be sown directly in late April until mid-August. Sow Kohlrabi seeds approximately 1cm deep in rows about 30cm apart. Kohlrabi tolerates dry conditions and does not prefer waterlogged soil, making it an ideal vegetable to grow in a raised bed.
Thin out the seedlings, and replant spaced approximately 6 inches apart.
Kohlrabi, like other brassicas (such as cabbage fly and club root), can be prone to pests and diseases, but it is slightly more resistant. Depending on the variety and sowing time, they should be ready for harvesting after 2-3 months.
When the bulb stem is swollen to approximately golf-ball to cricket-ball size, it is ready for harvesting. If it is allowed to grow any bigger, it will become woody and tough to cook. You can lift them, cut off the roots and leaves, and treat the leaves like spinach or other greens and enjoy them too.
Wash the bulb, but do not peel for the nutty flavour of the skin. Kohlrabi can be eaten raw or cooked.
To grow kohlrabi, focus on encouraging steady growth above ground rather than deep root development. The edible part forms as a swollen stem just above soil level, so even growth conditions help it stay tender and smooth. Sow seeds directly or start them under cover to protect young plants during the early stages.
Prepare soil that drains well and remains loose at the surface, as compacted ground can restrict stem expansion. When growing kohlrabi, water regularly at the soil level to support even swelling and prevent the stem from becoming tough as it matures.
Understanding when to plant kohlrabi helps you avoid stress that can affect stem quality. Seeds can be started early in the season under cover, with later sowings made outdoors once temperatures begin to rise. That way, you can continue to get consistent harvests over several months.
Outdoor sowing usually begins in late spring, once conditions are mild enough for healthy growth. Planting within this window allows kohlrabi to develop fully before cooler weather slows stem growth.
Spacing is important because the swollen stems need room to develop evenly without pressing against neighbouring plants. Leave around 10 to 15 centimetres between plants, with wider gaps between rows to allow airflow and access for maintenance.
Keep soil moisture consistent during dry spells, as irregular watering can cause stems to become woody. You can use light mulch to regulate moisture levels and reduce surface drying as the plant develops.
Harvesting should take place once the bulk stem reaches between golf-ball and tennis-ball size. If you’re wondering when to pick kohlrabi, earlier harvesting produces a sweeter texture and avoids toughness caused by overgrowth.
Cut the stem cleanly at the ground level and remove the leaves, which can be cooked separately like other leafy greens. Regular harvesting encourages you to enjoy the crop at its best quality.
Want to grow and enjoy crisp kohlrabi in your garden? At Allotment Online, we provide crop-specific advice to help your kohlrabi thrive from sowing to harvest.
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