Turnips are easy to grow when planted in the right season and mature in just two months. They are biennials, usually grown as annuals. Although turnips are more of a staple in European kitchens, many southern gardeners like to grow them for the nutritious turnip greens. Turnips grow best in a temperate climate but can endure light frost. Fall crops are usually sweeter and more tender than spring crops--and pest a much less of a problem. Turnips have been grown for over 3,000 years, and are especially valuable because all parts of the plants can be eaten. They are often used as a substitute for potatoes.
Turnips must be planted in full Sun in soil that is well-drained and loosened to a depth of 12 to 15 inches. They should be sowed as soon as the ground is workable. Turnip seed is scattered and covered with no more than 1/2 inch of soil. Once seedlings are 4 inches high, thin, if not growing for greens only. Water at a rate of 1 inch per week to prevent the roots from becoming tough and bitter.
You can harvest some turnips very early as turnip greens. Early types can be harvested after about 5 weeks. The main crop of turnips can be harvested after 6-10 weeks. Turnips can be harvested at any size, but small young turnips are nice and tender. Pull mature turnips before they become woody and before the final frost. Turnips can be stored for up to 3 or 4 months in a cool outdoor place covered with straw.