Turnips are a highly adaptable cool-season vegetable prized for their dual harvest of leafy greens and sweet, bulbous roots. A member of the Brassica family, this crop thrives when temperatures are moderate, making it an excellent choice for Tennessee gardens. Successfully cultivating turnips depends entirely on precise timing to allow for maturity during cool periods while avoiding the extremes of summer heat and hard winter freezes. Understanding the local climate cycle is the first step in ensuring a bountiful harvest.
Optimal Planting Windows for Turnips in Tennessee
The turnip growing season in Tennessee is divided into two distinct windows, timed to bypass the state’s hot summer months. The spring crop aims for an early harvest before intense heat causes the plants to “bolt,” or prematurely go to seed, resulting in bitter roots and tough greens. Seeds should be sown directly into the garden four to six weeks before the average date of the last expected spring frost.
For many areas across the state, this initial planting window generally falls between late February and mid-March. This early start allows the roots and greens to reach maturity within 40 to 60 days, typically leading to a harvest in late May or early June. Planting too late in the spring risks exposure to high temperatures, which can make the roots woody and unpalatable.
The preferred and generally more successful window for turnip cultivation is the fall crop, which benefits from naturally cooling temperatures. Planting should occur from late July through September to ensure the roots and greens develop during the mild autumn weather. The key is to time the planting so that the roots approach maturity just as the first light frosts begin.
Cooler weather and light frosts convert starches into sugars, improving the sweetness and mildness of the turnip roots. Gardeners can employ succession planting during this fall window, sowing small batches of seeds every two to three weeks. This practice ensures a continuous supply of young, tender greens and roots well into late fall and early winter.
Adjusting Timing for Specific Tennessee Regions
While general dates provide a guideline, Tennessee’s diverse geography requires gardeners to fine-tune their planting schedule based on location. The state spans several USDA Plant Hardiness Zones, ranging from 6b in the mountainous eastern regions to 8a in the warmer western parts. This variation means the average last and first frost dates can differ by several weeks.
Gardeners in East Tennessee, particularly those in higher elevations, often experience a later average last spring frost and an earlier average first fall frost. For example, some higher areas near Knoxville may see their last frost closer to mid-April, necessitating a later start for the spring crop. Conversely, the western areas of the state, which are generally warmer, experience earlier heat and milder winters.
These warmer conditions in West Tennessee mean spring planting must be initiated earlier and the harvest completed sooner to avoid the rapid onset of summer heat. To account for these shifts, consulting local resources, such as the nearest county extension office or a hyper-local planting calendar, is recommended. Adjusting the planting date by even a week or two based on the specific hardiness zone maximizes success.
Post-Planting Care and Soil Requirements
Once the optimal timing has been determined, success depends on providing the correct environment for development. Turnips require full sun, meaning a minimum of six hours of direct sunlight each day. The soil must be loose, well-drained, and amended with organic matter to prevent the roots from becoming stunted or forked.
An ideal soil pH for turnip growth falls slightly acidic to neutral, typically ranging from 6.0 to 7.5. Heavy clay soil should be avoided or heavily amended with compost to ensure proper drainage and prevent the roots from rotting. Seeds should be sown shallowly (one-quarter to one-half inch deep) and then thinned once seedlings develop their first true leaves.
Thinning is necessary for proper root development, leaving the remaining plants spaced four to six inches apart. Consistent moisture is paramount, as dry soil can quickly lead to tough, woody, and bitter turnip roots. Supplying about one inch of water per week, either through rainfall or irrigation, helps maintain the steady growth necessary for tender roots.
The greens can be harvested when they reach four to six inches in height by clipping the outer leaves and allowing the inner ones to continue growing. For the roots, it is best to harvest them when they are small (two to three inches in diameter) for the sweetest and most tender flavor. Fall-planted turnips can often be left in the ground until after a light frost, which concentrates their sugars and enhances their sweetness.