How to Grow Purple Top White Globe Turnips

Choose a sunny area of your garden for planting turnips. Prepare the soil by breaking up clumps with your garden spade and working the soil 10 inches deep. For spring planting, do this as soon as the ground is no longer frozen and can be worked. For fall planting, do this eight weeks before your region's expected first frost.

Add compost to heavy clay soil to loosen it up. Turnips require loose soil to allow the bulb to form properly. The amount of compost you need to add depends on how heavy and compacted the soil is. Rake it in to distribute it evenly through the top 10 inches of soil.

Create ridges in rows for the turnips using your garden spade. Make each ridge 8 inches high and keep the rows 24 inches apart.

Add 10-20-10 fertilizer to the ridges at the rate of 2 lbs. per 100 feet. Rake a hoe across the top of each ridge to flatten them out in preparation for planting.

Moisten the soil with your garden hose. Plant each turnip seed 1/2 inch deep and 12 per foot of row space -- once they start growing, thin them to two inches apart.

Place a rain gauge near your turnip crop. Give the turnips 1 inch of water per week, except for weeks when rainfall is at least that much.

Cover fall turnip crops with a 2- to 3-inch layer of straw mulch. This protects the turnips during colder weather.