Brassica oleracea (Gongylodes)
Kohlrabi is one of the most underrated and rewarding vegetables in the British kitchen garden. It forms a swollen stem bulb above soil level — crisp, sweet, and faintly nutty, tasting like a cross between a mild turnip and a fresh apple. It is equally good raw in slaws and salads, or roasted until caramelised and tender. Kohlrabi grows extraordinarily fast — from seed to harvest in as little as 6 to 8 weeks — and is one of the most reliable crops for successional sowing throughout the season. It is far easier to grow than most people expect, tolerating a wide range of soils and conditions, and producing handsome plants with architectural upright stems.
Kohlrabi comes in two colours — green-skinned and purple-skinned. Both taste essentially the same; the colour is skin-deep only. There are also giant varieties capable of growing to grapefruit size or beyond while remaining completely tender, and compact fast-maturing F1 hybrids suited to successional sowing. Choosing the right variety for your needs — whether speed, size, colour, or flavour — makes the difference between a good harvest and a great one.
The number of varieties shown for each crop is based on UK consumption data (2025/26) — the more popular the crop, the more variety choices we include.
Pale green-skinned kohlrabi — the most widely grown group. Fast, reliable, and excellent raw or cooked.
A reliable, compact green F1 hybrid producing smooth, uniform bulbs. Fast-maturing and suited to successional sowing throughout the season. Excellent fresh or cooked. Holds well without going woody.
One of the fastest-maturing kohlrabi varieties available. Very smooth, small to medium pale green bulbs of uniform shape. Ideal for close successional sowing at 2–3 week intervals.
The classic heritage green kohlrabi. Pale green-white round bulbs with a mild, sweet flavour. Open-pollinated — seed can be saved true-to-type. A British kitchen garden staple for generations.
Purple-skinned kohlrabi — identical flavour to green types but striking on the plot and in the kitchen. The skin colour is lost on cooking.
The most popular purple kohlrabi in the UK. Deep, vibrant uniform colour, smooth skin, and compact form. Reliable and fast. One of the best all-round F1 kohlrabis available.
The heritage purple kohlrabi. Classic round form with rich purple skin and a slightly earthier flavour than modern F1s. Open-pollinated and excellent for seed saving.
A vigorous purple F1 variety with very uniform, smooth bulbs and strong bolt resistance. Reliable performer across a long sowing season. Good choice for successional growing.
Varieties bred to produce huge bulbs that remain completely tender and sweet even at great size — unlike standard types which become woody if left.
The benchmark giant kohlrabi. Can grow to grapefruit size or larger — some specimens exceed several kilograms — while remaining crisp and non-woody throughout. Superb for slicing, roasting, and using raw in large-batch slaws.
Enormous pale green bulb reaching 25cm+ across. Still sweet and tender despite its size. Smooth skin and impressive form make it a talking point on the plot. A great variety for exhibition and for using in quantity.
A giant F1 kohlrabi with excellent uniformity and bolt resistance. Can grow to 2kg+ while remaining tender. Vigorous and reliable — combines the consistency of an F1 with giant variety characteristics.
Kohlrabi seed is widely available and inexpensive from all main online seed companies and garden centres. The main choice is between F1 hybrids (faster, more uniform, better for successional sowing) and heritage open-pollinated types (slower, more variable, but seed can be saved year to year). Garden centres stock the most popular varieties; online companies carry the full range including giant types.
Direct sowing is the standard and simplest method. Draw a shallow drill 1cm deep and sow thinly from March onwards. Thin to 20–25cm when seedlings reach 5cm. Net immediately after emergence. Sow a short row every 2–3 weeks for a continuous supply — this is more productive than one large sowing.
Suitable varieties: All varieties.
Sowing in modules allows transplanting into gaps left by earlier crops — useful for efficient bed management. Sow one seed per module at 1cm depth on a cool windowsill. Transplant at 3–4 true leaves with minimal root disturbance. Net immediately after planting out.
Suitable varieties: All varieties. Particularly useful for gap-filling mid-season.
A traditional companion combination — onions and brassicas complement each other well and may help deter each other's main pests. Growing onions at the edges of a kohlrabi bed is a well-established kitchen garden practice.
Beetroot and kohlrabi make efficient use of the same bed — both are compact, fast-growing crops that suit successional sowing in adjacent rows.
Nasturtiums act as a sacrificial trap crop, attracting aphids away from brassicas. Plant at the bed margins to protect kohlrabi from blackfly.
Kohlrabi is one of the simplest brassicas to sow — direct sowing from March onwards is the standard approach. Modules work well for transplanting into gaps or getting a head start. The key is successional sowing every 2–3 weeks rather than one large batch, and netting immediately after emergence.
Draw a shallow drill 1cm deep. Sow seeds thinly at 2–3cm spacing. Rows 30cm apart. Cover lightly and firm gently. Water in. From March outdoors, germination takes 7–10 days.
One seed per module at 1cm depth. Place on a cool, bright windowsill or in a cold frame at 10–18°C. Transplant carefully when seedlings have 3–4 true leaves — at 20–25cm spacing.
When direct-sown seedlings reach 5cm, thin to 20–25cm spacing. Use thinnings in salads — the small leaves are excellent. Never leave plants crowded — tight spacing produces small, distorted bulbs.
Immediately after sowing or transplanting, cover with fine insect-proof mesh (not fleece — it retains too much warmth). Flea beetle strikes fast and can defoliate young plants within days. Net first, every time.
Standard varieties: harvest at 5–7cm diameter — do not delay as they become woody quickly. Giant varieties: can be left until much larger. Pull the whole plant, twist off leaves, and use immediately or store in the fridge.
| Region | Sow / plant | Harvest | Notes |
|---|---|---|---|
| Scotland & Far North | Apr–Jul | Jun–Oct | Sow from April when soil warms. Two or three successional sowings give the best results within the shorter season. · Apr–Jul |
| Northern England | Mar–Aug | May–Oct | Direct sow from March in a sheltered spot. Net immediately. Successional sowing every 3 weeks gives continuous harvest. · Mar–Aug |
| Midlands & Wales | Mar–Aug | May–Oct | Long season. Sow every 2–3 weeks from March for continuous cropping from June to October. · Mar–Aug |
| Ireland & Isle of Man | Mar–Aug | May–Oct | Very well suited to the mild Atlantic climate. Sow every 2–3 weeks. Net against flea beetle throughout. · Mar–Aug |
| South & SE England | Mar–Aug | May–Nov | Widest window. Late August sowings can give harvests into November. Successional sowing is the key technique. · Mar–Aug |
| South Coast & SW | Mar–Sep | May–Nov | Latest sowings possible in September for autumn harvest. The mild climate suits kohlrabi very well. · Mar–Sep |
Fine insect-proof mesh applied immediately after sowing or transplanting is the most important single action for kohlrabi. Flea beetle — the small jumping beetle that creates tiny round holes in leaves — can defoliate young plants within days and significantly reduce growth. The mesh must go on at sowing or planting time, not after damage appears. Cabbage white butterflies also target kohlrabi — the same mesh prevents egg-laying.
Consistent moisture produces smooth, crisp, well-shaped bulbs. Irregular watering — particularly a dry period followed by heavy rain or watering — causes the stem to crack or split. Water regularly throughout the growing period, particularly during dry spells in June and July. Mulching between rows helps retain moisture. Containers need daily checking in warm weather.
Standard varieties must be harvested promptly — at 5–7cm diameter they are at their sweet, crisp best. Left much larger, the flesh becomes woody and fibrous. Check plants daily as they approach harvest size. Giant varieties (Superschmelz, Gigante) are bred to stay tender at much larger sizes and can be left to grow on. Young kohlrabi leaves are edible — use in salads or stir-fries; they're excellent and are often wasted.
Kohlrabi left too long becomes woody and tough — standard varieties must be harvested at 5–7cm diameter without delay. Flea beetle is the primary pest threat; fine insect mesh applied immediately after sowing or transplanting is the only reliable protection. Net first, not after the damage appears. Giant varieties (Superschmelz, Kossak F1) are the exception — bred to stay tender at much larger sizes.
Full identification and treatment advice is in the Pests and Diseases sections.
Kohlrabi keeps well in the fridge for up to 2 weeks. Remove the leaves and store the bulbs unwashed in a sealed bag in the salad drawer. The leaves deteriorate quickly and draw moisture from the bulb — always remove them before storage. Wash and peel just before use.
The best approach is successional sowing and harvesting on demand rather than storing a large batch. A row sown every 2–3 weeks gives fresh kohlrabi continuously through the season. Harvest standard types the moment they reach 5–7cm — do not leave them in the ground past their best.
Kohlrabi is excellent raw — sliced into thin matchsticks or grated into slaws, it has a fresh, clean, slightly sweet flavour. Roasted in wedges at 200°C it caramelises beautifully. Steamed or boiled until just tender it works well as a side vegetable. The leaves can be cooked like spinach or kale. Use within a day of harvest for best raw eating.
A single large sowing of kohlrabi produces a feast-and-famine glut — all plants mature within a few days of each other. Sow a short row or half-tray every 2–3 weeks from March to August and you'll have fresh kohlrabi continuously from June to October. It takes under 5 minutes per sowing and transforms this crop from occasional to constant.
Flea beetle is the main threat to kohlrabi seedlings and it moves fast. The tiny jumping beetles create small round holes in leaves and can defoliate young plants completely within a few days of emergence. Fine insect mesh over the bed from the moment of sowing is the only reliable protection. Fleece works as a temporary measure but mesh is better — it lets more light and rain through.
Superschmelz and Gigante are not standard kohlrabi left to overgrow — they are specifically bred varieties where the flesh remains crisp, sweet, and non-woody even at grapefruit size or larger. A single Superschmelz can weigh several kilograms and still be excellent raw or roasted. They need the same care as standard types but more space — 35–40cm between plants.