Turnips (Brassica rapa) are a fast-growing, cool-season crop prized for their leafy greens and globe-shaped roots. Planting them in the spring is possible, but it is a race against the unpredictable arrival of summer heat. A successful spring harvest relies on quick growth and timely planting before rising temperatures compromise the quality of the vegetable.
Understanding the Difference Between Spring and Fall Turnips
The purpose and outcome of a spring turnip crop differ significantly from those planted in the fall. Spring-sown turnips are grown for a rapid harvest, focusing on tender, mild-flavored greens and smaller roots. The goal is to complete the entire growth cycle, typically 30 to 60 days, before the weather becomes consistently warm.
Fall turnips benefit from a longer growing season, starting in late summer and maturing as temperatures cool. This extended period allows the roots to swell and accumulate sugars, resulting in a larger, sweeter, and more robust harvest. The fall crop is generally considered superior in root quality and tenderness due to the effects of light frost near maturity.
Ideal Timing and Soil Conditions for Spring Planting
To maximize the short window of cool weather, turnip seeds should be sown directly into the soil as soon as it becomes workable in early spring. This timing is often two to four weeks before the average last expected frost date for your region. Turnip seeds can germinate when the soil temperature is as low as 40°F, but the optimal range for quick emergence is between 60° and 105°F.
Turnips thrive best in full sun and loose, well-draining soil to accommodate the expanding root. Prior to planting, amend the area with aged compost or organic matter, loosening the soil to a depth of 12 to 15 inches. Direct sowing is recommended, as turnips do not tolerate transplanting well due to their delicate taproots. Once seedlings emerge, thin them to a spacing of four to six inches apart to prevent overcrowding and ensure proper root development.
Managing Heat Stress and Harvesting Spring Turnips
The biggest threat to a spring turnip crop is bolting, the premature growth of a flower stalk. Bolting is triggered by environmental stress, most often a sudden spike in temperature, causing the plant to divert energy away from the root to produce seeds. Once a turnip bolts, the root typically becomes woody, fibrous, and develops a bitter flavor.
To mitigate heat stress, consistent and deep watering is essential to keep the soil evenly moist. Applying a thick layer of organic mulch, such as straw, helps regulate the soil temperature and prevents overheating during warm spells. Spring turnips must be harvested quickly, generally within 30 to 60 days of planting, before the summer heat becomes consistent. Greens can be harvested once they are four to six inches tall, and roots should be pulled when they are small, typically two to three inches in diameter, for the best texture and flavor.