Turnips have been cultivated in Europe for over 4000 years and are probably native to central and southern Europe. They are now commonly grown and widely adapted as a root crop even in the tropics. The tubers have white or yellow flesh, the tops (greens) are medium green and hairy.
Both the greens and the tubers of the turnip are edible. Livestock forage on the tops and the roots since improved varieties form tubers partially above ground level making them easier to graze.
- Elevation- Turnips succeed best at 1000 m (3200’) or higher.
- Rainfall- Plants are shallow rooted and do not tolerate excessive rainfall or poor drainage. 900-1400 mm (35-55”) of rain is sufficient.
- Soil Types- A pH level of 4.2--7.8, plenty of organic matter in loose, well-drained soil will produce a crop of roots 4-6 cm (1.5-2.3 “) in diameter after 60-70 days.
- Temperature Range- Basically a cool climate crop, up to 27ºC (80ºF), it is resistant to frost and mild freezes. Some shade is preferred for tender greens.
Sow seed thinly at a depth of 1-2 cm (½ “) in rows 25-30 cm (9½-11½”) apart. Thin to 10 to 15 cm (4-6”) apart. Turnips can be planted in the same spot after early vegetables, are harvested but not after other root crops.
Harvesting and Seed Production
Roots may be harvested for human consumption or left in the ground longer for animal feed. Turnips should be dug before a heavy freeze, the tops cut off and crated or placed in small piles on earthen floors. Storage temperatures should be 0- 1.5°C (32- 35ºF) with relative humidity of 90-95 %. Flowering and seed set takes place at cool temperatures when days are long. Pollination by bees is critical but the crop must be separated from other members of B. rapa.by more than 500 m. (1500’) to avoid cross-pollination. After seed pods turn tan, cut the whole stalk, pile in a heap to cure for five days, then thresh. Storage of seeds at 18-22º C (62-70º) at relative humidity of 60-80% will keep turnip seeds viable for 5 years.
Pests and Diseases
Clubroot and black rot are the most serious diseases, but powdery mildew and nematodes can also be a problem. The most injurious insect pests are turnip aphid, root maggot and flea beetles. Crop rotation helps to control diseases. Seeds can be treated in hot water for 25 min. at 50ºC (122ºF) to reduce incidence of black rot.
Cooking and Nutrition
Young turnip leaves and tubers can be served raw in salads. Older leaves and tubers are best cooked. Tubers are high in iron, vitamins A and C, potassium and calcium. Leaves are a good source of vitamin A and fiber.