Select a planting site in full sun that is well-drained. Till or dig the soil, pulverizing it until it is finely textured and light. Spread about 1/2 inch of compost over the soil, and mix it in. Rake the prepared ground to make a smooth bed.
Gently lift the turnip seedlings from the growing container, and separate them carefully so the roots are disturbed as little as possible. The seedlings should have a single, long taproot and a few small feeder roots.
Make a hole in the prepared planting bed with your finger, and gently slide the root of a seedling into the hole. Press the soil around the root to firm the seedling in place. Turnip roots are easily damaged during transplanting, but you may be able to grow some edible round roots if you make sure the taproot is not bent or folded during transplanting. Turnip greens will grow easily from transplants.
Set the transplants in parallel rows about 8 inches apart, with about 4 inches between transplants in the rows for a compact bed-growing method. Alternate the transplants so they are not directly across from each other in the rows to give each plant more space to grow.
Water the transplants to settle the soil against the roots. Spread a thin layer of mulch between the plants to retain soil moisture and to discourage weed growth. Use a light mulch, such as dry, chopped straw or shredded, dry leaves.