By Josie Borlongan, Garden Guides Contributor
Turnips (Brassica rapa Rapifera Group) are biennials but grown as annuals. Turnips grow up to 9 inches (23 cm) high with a spread of approximately 10 inches (25 cm). Turnips are root vegetables and are commonly grown in temperate climates approximately 68 degrees F (20 degrees C). They are characterized by a white, bulbous taproot that grows underground averaging in size between one and three inches (2.5 to 7 cm) in diameter and are mostly round or bulb-like in shape.
Turnips are usually hardy and can tolerate light frost. Turnips require a well-drained, fertile and moisture-retentive soil. Rotate turnips to avoid build-up of clubroots. If this is a problem, lime the soil to bring the pH to 6.5 to 7. Turnips need medium levels of nitrogen, using fertilizer with 21 percent N content should be approximately 1 1/2
to 2oz. per square yard (45 to 55 g per square meter). Avoid planting turnips in ground with fresh manure ground because this can cause overly lush growth, making them more susceptible to pests. A base-dressing may be applied to the area before planting.
A turnip's flesh is either white or yellow and the skin white, pink, red or yellow. The young leaves are edible and resemble mustard greens. Both turnip leaves and taproots have a characteristic pungent flavor similar to that of raw cabbages or radishes that turns mild after cooking.
Choosing a Variety
The recommended turnip varieties are Golden Ball, Hakurei, Just Right, Purple Top White Globe, Royal Crown, Tokyo Cross and White Lady.
Turnips can be planted during spring, from the beginning and end of June or as soon as the ground is workable. Some turnips have been sown as early as May. You may also sow turnip seeds under cover. Sow seeds in succession at three-week intervals until early summer. Main crop types can be sown in late summer in their natural environment, ¾ inch (2 cm) deep. The early types should be spaced in rows that are 9 inches (23 cm) apart, thinning to 4 inches (10 cm); while main crop types should be spaced in rows 12 inches (30 cm) apart, thinning to 6 inches (15 cm).
Ensure that your turnip beds are weed-free. Water turnip plants at a rate of 2 gallons per square yard (11 liters per square meter) during dry weather condition.
Flea beetles, slugs and snails have been known to affect seedlings. Caterpillars, whiteflies, mealy aphids and clubroots attack plants at all stages of growth. Other problems or diseases include boron deficiency, powdery mildew and downy mildew. Discard affected clubroots when these problems arise.
Harvesting and Storage
Turnips can be harvested about five weeks for early types and after six to ten weeks for main crop types. Harvest turnips by pulling them from the soil by their leaves. Do not leave them in the ground too long for they may become woody. Store turnips for up to three to four months in outdoor piles then cover them with straws.