Grow your own
The versatile, easy-to-grow kohlrabi.
A member of the brassica family, kohlrabi – from the German “kohl”, meaning cabbage, and “rübe” meaning turnip or beet – is believed to have developed from a thick-stemmed species of wild cabbage. Rather than being a root or a head, it’s an enlarged stem, which some people believe arrived from outer space thanks to its sputnik-like appearance. We, however, hail kohlrabi as the new spiritual leader of the vegetable patch.
Looks aside, kohlrabi is a versatile, easy-to-grow and pest-resistant cool-season crop. Although it’s best suited to autumn planting – get ready to jump in now – in more temperate parts of Australia kohlrabi grows well throughout spring, too.
This makes it a plant that can happily go in your vegetable patch at nearly any time of the year.
Like other brassicas, kohlrabi demands soil that’s high in nitrogen. If possible, follow on from where you planted beans in the spring and summer because the soil will be loaded with nitrogen. Otherwise, make sure you use plenty of compost and slow-release organic fertiliser.
Turn over the chosen patch of soil, making sure it’s aerated and friable, which will allow an easier passage for the kohlrabi’s roots.
Not overly fussed about sunlight, this plant will cope well with part shade, so choose a position accordingly. Sow seeds directly into soil at a depth of around a centimetre and spaced 20 to 30 centimetres apart. Water the seeds twice daily until they germinate, which should occur within seven to 10 days, and then cut back watering to once a day for the first month.
Once the plants are set, they’ll be relatively hardy and only need watering every second day (more often if they’re planted in pots). Although kohlrabi remains largely pest free, like with all brassicas, it’s worth keeping an eye out for white cabbage moths. In the absence of other brassica varieties of crops, these pests may take a shine to your new seedlings.
Netting is the only certain way of keeping caterpillars at bay. Make sure you keep the netting taut with some clearance from your plants; if the netting hangs on the foliage, the moths can make a landing spot for their larvae and the caterpillars will not be far away. If you take your chances without netting and encounter a moth problem, use a bioinsecticide such as Dipel to control the damage.
Taking its growing habits more from a turnip than a cabbage, kohlrabi has a relatively quick turnaround time and the plants may be ready to harvest within eight to 10 weeks. Initially the plants produce foliage, which can be picked in moderation – these green leaves can be used in stir-fries and soups. But at the two-month mark the stem begins to swell. This is when the real show begins and the plant begins to resemble a vegetable from out space.
While all parts of the kohlrabi are edible, the true prize of the vegetable is found under the root’s outer layer of skin: its creamy yellow flesh. It’s important not to let the plant overripen in warmer conditions – it will become fibrous and woody. Kohlrabi lasts well in cool soils, however, and develops more flavour as its starch turns into sugar.
Eaten fresh when it’s young, kohlrabi has a good crunch and the mildly spicy aftertaste of radish. Kohlrabi is often roasted or steamed and served with a cosy white sauce, but it can also be grated and added to coleslaw or made into fritters.