Like many leafy greens, root veggies, and brassica relatives, turnips are a spring and fall crop, and mature plants can even tolerate a light touch of frost. Check your first and last frost dates in order to plan your planting for the end of winter or the beginning of fall.
Growing From Seed
Plant seeds directly in the soil, 3-6 inches apart in rows roughly 10-15 inches apart. Picture the root size (like a tennis ball), and make sure they won’t be overcrowded as they grow. Water thoroughly, as the hard little seeds must stay moist to germinate, but they are too small to plant deep in the soil and so risk drying out. The Maine Organic Farmers and Gardeners Association recommends pre-soaking the furrows where you will be planting if you haven’t had rain. Fortunately, turnip seeds germinate quickly.
Turnip Plant Care
Turnips are hardy and un-fussy, but a bit of weeding is important. Keeping in mind that the underground part of the plant is fairly close to the surface, use a hand hoe such as the Japanese type or a long-handled beet hoe, and slide the blade just under the surface of the soil to eliminate weeds without disturbing the turnips. Some growers like to mulch around turnips, while others find that mulch gives pests a hiding place.
Soil and Nutrients
Turnips need friable soil with plenty of organic matter to grow their globe-shaped root. Like other root vegetables, it needs good drainage that doesn’t leave it sitting in too much water and rotting or getting diseases. Lighter soil will also brush off more easily when you harvest turnips. Preparing the soil ahead of planting by mixing in an all-purpose vegetable fertilizer is easier and more effective than trying to correct soil after planting. Turnips need phosphorus for the root to form properly and some nitrogen for the vegetative growth, but not too much or the greens will grow bigger at the expense of the root.
If you can, test the soil for any mineral deficiencies, in particular for boron. If your soil lacks boron, turnips will become hollow or brown in the center, but a rich compost or a boron amendment can prevent this. For organic growers, check the OMRI-approved list of products.
The University of Minnesota Extension notes that while turnips have a big storage root, they don’t have a far-reaching root system.3 They recommend watering 1 inch per week and checking how deep the water soaks in (use a trowel to peek or a moisture meter). The depth water reaches will vary by the type of soil in your garden, with sandy soil allowing the water to go deeper than heavy, clay soil.
If you use a sprinkler for watering, you can measure with a rain gauge to find out how long it takes to reach 1 inch and set your timer accordingly. For drip irrigation, however, the time required for 1 inch depends on flow rate and emitter spacing.
Common Pests and Diseases
Crop rotation—planting where other Brassicas have not been planted recently—will help you avoid diseases such as clubroot and black rot, especially since many typical problems come from fungal spores that stay in the soil. Get rid of any diseased plants right away. Root maggots live in the soil, so crop rotation may make your turnips harder for them to find, but a dusting of diatomaceous earth is good protection as well.
Sprinkle wood ash around turnips to deter root maggots. Floating row covers over young plants may protect from flea beetles and other leaf-munching bugs. Fence out pests such as voles with a quarter-inch wire mesh planted 10 inches deep in the ground and 12 inches high above the ground.
You have a few key varieties to choose from if you’re growing turnips.
Purple-top turnips have a magenta-purple color at the top of the root, store well, and offer plenty of delicious greens.
Japanese-style white turnips like Shogoin or Hakurei are smaller, white, tender, and crunchy enough to eat raw. Try them sliced and sautéed in sesame oil. You can also try red-skinned Japanese varietals like Tsugaru Scarlet and Hidabeni; get these from specialized seed companies.
Yellow varietals like Orange Jelly, Yellow Globe, or Yellow Dutch turnips have a richer taste and additional nutrients. These are especially good for shredding in a slaw or pickling/fermenting.
How to Harvest Turnips
Harvest your spring crop before the weather turns warm, as heat will alter the flavor. Fall and winter turnips benefit from the chill. Brush away dirt at the top of the root to assess the size. When turnips are ready, loosen the soil around them with a spade or fork, then, holding the stems near their base, pull gently. Do not wash the turnips. Separate the nutrient-rich greens from the root and store them in a slightly damp paper towel in the refrigerator, but enjoy them as soon as possible. Let the roots dry a little bit, then dust off any remaining soil.
How to Store and Preserve Turnips
If you have a root cellar, that is the ideal, traditional place to store turnips and other root vegetables, as it is cool and relatively humid. Otherwise, store turnips in your vegetable crisper, just above 32 degrees F. Turnips with the greens still attached will last for just a few days