Growing kohlrabi is really easy to grow – far easier than broccoli or cauliflower. Bigger types store well, either fresh or frozen. The leaves are similar to kale and have a strong ‘greens’ flavour, while the bulb has crisp texture and a delicate, sweet taste. They can be grated for coleslaw, diced raw for a salad, or added to a stir-fry and cooked.
One of the less well-known brassicas, kohlrabi produces a round edible bulb just above the ground. Some varieties should be picked when smaller than a tennis ball, while others can be allowed to get…really, really big.
Kohlrabi bulbs either have a purple or white skin and this should be peeled off before eating. They’re wonderfully odd-looking plants, especially the red ones, and might make you think little vegetable aliens have landed in the garden.
Many suppliers have seeds for the smaller varieties, often in F1 hybrid form, but Real Seeds carry both a smaller purple kohlrabi called ‘Azur’, and a HUGE variety called ‘Gigant’ – both of which are open-pollinated, so you can save seeds from them for future crops. Gigant can grow up to 4kg, and while many vegetables lose flavour if grown too big, this one keeps its great flavour without becoming woody.
Growing kohl rabi
Kohlrabi can be sown direct or started in modules. They are tolerant of a wide range of soils but they don’t like to dry out; a mulch around the growing plants will help to keep the soil moist. Plant out (or thin) to 15cms apart, in rows spaced 25cms apart.
Like all brassicas, kohlrabi are hungry feeders and will do best if given plenty of compost. They like full sun and well-drained soil. Sow smaller types from March to May for a staggered harvest beginning in June. Giants can be sown at the same time, but will stand for much longer and can be picked in October and beyond. Mature kohlrabi is hardy enough to stand a few degrees of frost, so it can be left in the ground until really cold weather is forecast.
Smaller types tend to bolt if they are left to grow for too long, so read the seed packet to find what size to pick them at. If you miss your chance and the plants begin to bolt, don’t sling them on the compost heap – they will still be perfectly good to eat. Bolting doesn’t change the flavour much, even if the bulb has become a tapering cone 25cms tall. Pick it, peel it, and you’re almost ready to eat it.
Try kohlrabi raw (it’s a bit like a not-very-sweet melon), grated for coleslaw, diced in a stir fry or blended for soup. It’s an easy and versatile vegetable, and once you’ve tried it you will probably want to give it garden space every year.
Without any preparation, big kohlrabi store much better than small ones. Tie up the leaves and store in sacks in dark, cool sheds. Alternatively, peel and dice them, blanch briefly, and bag for the freezer.
Like all brassicas, kohlrabi is prone to attack from ‘cabbage white’ butterflies. Either protect the plants with netting, or grow them in a polytunnel. Smaller varieties, being fast growing, are less prone to caterpillars than slower-growing cabbages and broccoli. Slugs may drill holes into the bulbs if given the chance so keep the area around the beds clear of grass, weeds and debris so they have nowhere to hide.