Turnips are a dual-purpose cool-season crop, valued for both their leafy greens and their fleshy taproots. Successful cultivation in Ohio depends on timing the planting to avoid summer heat, which negatively affects root quality. As members of the Brassica rapa species, turnips thrive when temperatures are moderate, ideally between 40°F and 75°F. Gardeners must utilize Ohio’s two distinct cool-weather windows to maximize the yield for either greens or roots.
Spring Planting Timing and Goals
The window for spring planting opens as soon as the soil becomes workable, typically 4 to 6 weeks before the average last expected spring frost in Ohio. This early start, usually around late March or early April in the southern parts of the state, is necessary to complete the harvest before summer heat arrives. The primary goal of a spring crop is often the turnip greens, as the roots are less reliable.
As the days lengthen and temperatures rapidly increase toward late spring, the turnip plant shifts its energy from root growth to reproduction. This causes the plant to “bolt,” or send up a flower stalk, which makes the root woody and bitter. Consequently, spring-planted roots must be harvested immediately when they reach a small size to ensure they remain tender. The greens, however, can be harvested selectively throughout this early growing period.
Fall Planting for Root Development
Fall is the superior season for growing the large, sweet, tender turnip roots most gardeners desire. Planting centers on counting backward from the average date of the first expected hard frost in your specific Ohio region. Turnips require approximately 60 to 75 days from seeding to maturity, meaning the ideal planting time falls between late July and early August.
Gardeners in Northern Ohio, which experiences an earlier first frost, must plant sooner than those in the warmer Southern counties. This timing ensures that the roots develop fully during the mild late summer and early autumn. The decreasing soil temperatures and shorter days of fall are suited for encouraging root expansion without premature bolting.
Essential Soil Preparation and Sowing
Turnips require deep, loose, and well-draining soil for smooth, unbranched root formation. Loosen the soil to a depth of at least 12 to 15 inches, amending heavy clay soils with organic matter. Incorporating a two-inch layer of finished compost or well-rotted manure improves drainage and structure without providing excessive nitrogen, which can lead to forked roots.
Direct-sowing is the preferred method, as root crops do not transplant well and disturbing the taproot leads to misshapen growth. Seeds should be placed shallowly (one-quarter to one-half inch deep) and kept consistently moist until germination. Once seedlings develop their first set of true leaves (2 to 3 weeks after germination), they must be thinned to a final spacing of 4 to 6 inches apart.
Thinning is performed by gently snipping excess seedlings at the soil line rather than pulling them out, which can damage the roots of remaining plants. Proper spacing eliminates competition for water and nutrients, allowing each plant sufficient room to swell into a full-sized root. Overcrowding is the most common cause of small or woody turnip roots.
Harvesting Your Turnips and Greens
The turnip greens can be harvested as a “cut-and-come-again” crop by selectively plucking the outer leaves, cutting them about two inches above the crown. This allows the plant to continue producing foliage while directing energy toward the root. The roots are ready for harvest once they reach a diameter of 2 to 3 inches, though many varieties remain tender until they reach the size of a tennis ball.
The peak flavor of the fall turnip crop is achieved after exposure to a few light frosts. This initiates cold-induced sweetening, where the plant converts stored starch reserves into sugars (such as sucrose) as a natural cryoprotectant. This conversion results in a sweeter and milder flavor profile.
For long-term storage, the roots should be harvested before a hard, deep freeze and the greens trimmed to only a half-inch stub. The unwashed roots store best in a cold, moist environment, ideally between 32°F and 40°F with high humidity. They can be stored for several months when layered in a material like moist sand or sawdust in a cool cellar or basement.