Brassica oleracea var. gongylodes.
A botanical curiosity born in northern Europe in the 16th century, and one of the last great members of the extraordinary cabbage family to be invented by human selection. The German name Kohlrabi tells you all you need to know: Kohl (cabbage) + Rabi (turnip) — a turnip-shaped cabbage, or rather a cabbage whose stem, through mutation and patient peasant selection, swelled into a ball above the ground rather than staying straight or forming a dense head of leaves. First mentioned by the Italian botanist Mattioli in 1554, it spread quickly into German and Central European kitchens, where it remains today a winter vegetable as common as the carrot is here.
A plant of almost extraterrestrial appearance: a plump ball 5 to 8 cm across at maturity (ideally the size of a medium apple), perched as if suspended a few centimetres above the soil, bristled with long upright leaf petioles reaching for the sky. The purple variety bears the ball in a deep, highly decorative violet, but cut open it reveals a slightly pearly white-green flesh identical to that of the green cultivars. Fine, mild, crunchy flavour, halfway between an apple and a broccoli stem, with a lightly sweet note.
Multi-use: peeled and sliced raw into sticks for dip or coleslaw, grated into a mustard rémoulade, cubed for a quick stir-fry, roasted in caramelized quarters in the oven, or simply sliced thin into a German kohlrabi schnitzel (breaded like an escalope). The leaves, often discarded, are delicious sautéed like kale.
Grower's tip: It's one of the fastest and easiest cabbages. Indoor start 4 to 6 weeks before transplanting for the summer harvest, or direct-sow early to mid-July for the fall harvest (often the most beautiful, improved by the first frosts). The absolute golden rule: harvest when the ball is the size of a tennis ball (5 to 8 cm across) — beyond that, it turns woody, fibrous and only fit to feed the chickens. Better to harvest too young than too old. Like all cabbages, susceptible to the cabbage worm — insect netting from transplanting on. Bonus: its modest size makes it an excellent vegetable for small gardens and raised beds.
- Open-pollinated. Biennial — flowering only occurs in the second year. Insect-pollinated; crosses with all other Brassica oleracea (cabbage, broccoli, kale, etc.) — isolate rigorously for seed saving.
- Height: 25 to 35 cm for the foliage; ball just a few centimetres above the soil.
- Maturity: 50 to 60 days after transplant.
- Exposure: full sun; part shade accepted in summer.
- Rich, well-drained, slightly alkaline soil. Space plants 20 to 25 cm apart.
- Indoor start 4 to 6 weeks before transplanting for summer harvest, or direct-sow early to mid-July for fall harvest. Strict rotation with other crucifers.
