Turnips grow and taste best when they come to harvest in cool weather.
For a late spring harvest, sow turnip seeds directly in the garden 2 to 3 weeks before the average last frost date in spring.
Sow turnips in late summer for autumn harvest; in early autumn for late autumn harvest; and in late autumn for winter harvest in reverse-season regions.
The turnip is a hardy, cool-weather biennial grown as an annual. The turnip has a rosette of bright green leaves growing from a swollen, root-like base or tuber. Turnips are grown as a root vegetable or for their green leaves.
Soil Even though it's known as "potting soil", the best medium for seed starting is a sterile soil, that’s labeled for seed starting. Never use garden soil, which often drains poorly and may harbor disease organisms. This step should pertain to all plants started from seeds.
Turnip Planting Time. Turnips are a cool-weather crop that require 30 to 60 days to come to harvest. Turnips grow best in temperatures from 40°F to 75°F. They are best harvested before temperatures exceed 75°F. Sow turnip seeds directly in the garden 2 to 3 weeks before the average last frost date in spring for a late spring or early summer harvest. Sow turnips in late summer for autumn harvest; in early autumn for late autumn harvest; and in late autumn for winter harvest in reverse-season regions.
Planting and Spacing Turnips. Turnips do not transplant well. Sow seed directly in the garden ½ inch deep and 1 inch apart in wide rows, thin successful seedlings from 4 to 6 inches apart. Space wide rows 12 to 24 inches apart. Thin turnips grown for greens from 2 to 3 inches apart.
Water and feeding. Keep the soil moist to keep turnips growing as fast as possible. Do not let the soil dry out. When turnips grow slowly their roots become woody and strong flavored. Side dress turnips with aged compost at midseason.
Turnip Care. Keep planting beds weed free. Overcrowding may cause small roots. Mulch turnips with straw to protect the tuber tops from sunburn.
Container Growing Turnips. Turnips greens are easily grown in containers. Small turnip roots can be grown in wide containers at least 8 inches deep.
Turnip Harvest. Turnips come to harvest 30 to 60 days after sowing. Lift roots when they are 2 to 3 inches in diameter; lift them carefully with a garden fork. Leaves can be cut when they are 12 inches long; cut outside leaves first. Thinned seedlings can be harvested for greens.