Best Kohlrabi Varieties for Scotland

Kohlrabi is one of the quickest brassicasThe cabbage family: cabbage, kale, broccoli, cauliflower, Brussels sprouts, kohlrabi, swede, turnip and more, sharing the same pests, diseases and rotation rules. Full definition →, ready in as little as six weeks, and it suits a cool climate. The four recommended varieties differ in how fast they grow and how well they resist boltingA plant switching early into flowering and seed production, usually triggered by stress, after which leaves, roots or bulbs turn bitter or unusable. Full page → and mildew, and Kossak grows larger than the rest.

What Scotland means for the choice

Cold can make kohlrabi bolt, which stops the bulb swelling, so early crops are best sown indoors. That's worth heeding in a Scottish spring, and it makes Olivia's slowness to bolt useful. Green varieties can be sown early, while purple ones tend to be hardier, which makes them a good choice for late-summer sowings that crop in autumn. Kohlrabi is a brassica, so clubroot is the main soil worry: the plants prefer light, non-acid soil, and the advice is to lime if the pH is below 6. Much of Scotland's soil is naturally acidic, so it's worth testing. The kohlrabi growing guide covers the sowing calendar, spacing and seedling protection.

Kolibri, Olivia and Korist hold the RHS Award of Garden Merit (AGMThe RHS's Award of Garden Merit: a UK-wide trials award for reliable performance, not a Scotland-specific recommendation. Full definition →). Kossak doesn't.

Olivia

Olivia is a green-skinned variety with a small, globe-shaped, light green stem, upright dark green leaves and tasty white flesh. It's slow to bolt and has a good tolerance of mildew and other fungal diseases, which helps in a damp garden. It suits successional sowingSowing a small batch of seed every couple of weeks, rather than all at once, so crops mature in a staggered sequence instead of a single glut. Full definition →, a short row about every three weeks, for a steady supply rather than a glut.

Korist

Korist is a globe-shaped green kohlrabi with juicy, mildly sweet white flesh. It's good for early sowings, has excellent resistance to downy mildew and a long holding ability, so it stays good in the ground for longer once it's ready. That's useful if a wet week keeps you out of the garden.

Kolibri

Kolibri is an attractive, compact purple kohlrabi with pure white, succulent flesh and upright green leaves. It's easy to grow and ready in under eight weeks from sowing, but pick it young: the stem turns bitter as it matures.

Kossak

Kossak is a large, fast-growing, pale green kohlrabi with a mild taste, ready in about three months. It's rated H5 against H3 for the other three, and it grows in firm, fertile soil, including in coastal regions. It doesn't hold the AGM.

Which one for your situation

• Most gardens, or a damp spot: Olivia.
• The earliest sowing, or a crop that holds in the ground: Korist.
• The quickest crop: Kolibri, picked young.
• The biggest bulbs: Kossak.
• A late-summer sowing for autumn: Kolibri, since purple types tend to be hardier.

Young plants are eaten by slugs and flea beetle, and Kossak can also be hit by cabbage root fly and small white butterfly caterpillars, so protect seedlings whichever you grow.

Common questions

Sources