Turnip greens, the leafy tops of the Brassica rapa plant, are a dual-purpose crop cultivated for both their nutritious foliage and their edible root. This cool-weather vegetable performs best when grown outside the heat of summer, thriving in temperatures that encourage sweet, tender leaves. Successful cultivation relies on precise timing; planting too late or too early can cause the plant to become bitter or prematurely flower. Understanding the specific seasonal windows for planting is the most important factor for a productive harvest of these peppery greens.
Timing the Spring Planting Window
Cultivating a spring crop requires careful attention to avoid the risks of a late freeze and early summer heat. The planting window opens roughly two to four weeks before the average date of your last expected spring frost. This early start allows the seeds to germinate in cool soil, often around 40°F, and establish themselves while conditions are still favorable.
While turnip greens tolerate light frosts, the primary limitation of the spring season is bolting. Bolting occurs when the plant shifts energy from leafy growth to producing a flower stalk and seeds, triggered by sustained exposure to warmer temperatures and longer daylight hours. Once daytime temperatures consistently climb above 75°F to 80°F, the leaves quickly become tough, pungent, and bitter, signaling the end of the spring harvest. This narrow timeframe means spring greens are usually a quick, single-harvest crop.
Why Fall Planting is Preferred and How to Calculate the Date
The fall season is the superior time to plant turnip greens because gradually cooling weather naturally improves the crop’s flavor profile. As nighttime temperatures consistently drop into the 40s°F, the plants convert starches into sugars, resulting in a sweeter and crisper texture. The shorter days and descending temperatures also reduce the risk of premature bolting, allowing for a longer, more reliable growing period.
Calculating the precise fall planting date requires counting backward from your region’s average first frost date. A typical turnip green variety takes about 40 days to reach maturity, but this period slows down as days shorten and temperatures fall. To ensure a substantial harvest before the ground freezes, gardeners should count back a minimum of 60 days from the first frost. This 60-day period accounts for the 40 days to maturity plus a four-week buffer for harvesting and compensating for the slower growth rate.
This backward calculation means planting occurs during late summer, often in late August or early September in northern climates. Regions with mild winters, such as those in USDA Zones 9 and 10, can successfully sow seeds throughout the fall and even into the winter months. Planting at the correct time ensures the plants mature just as the first light frosts arrive, maximizing the development of sweet, tender leaves.
Extending the Harvest with Succession Planting
To ensure a steady supply of tender leaves and avoid a single glut of mature greens, employ the method of succession planting. This involves staggering sowings throughout the cool-weather season, both in the spring and the fall. The recommended interval for turnip greens is to plant a new batch of seeds every 10 to 14 days.
This continuous sowing strategy ensures that a fresh set of young, optimally flavored leaves is always ready for picking. Planting a small quantity every two weeks maintains a continuous supply of baby greens, which are often the most tender and least pungent. This technique is especially useful in the fall, where the extended cool period allows for multiple waves of harvest up until the hard freeze.
Harvest Timing and Temperature Limits
The time from planting to the first harvest of leaves is relatively short, with most varieties yielding baby greens in 30 to 40 days. If the goal is a dual harvest of both greens and a sizable root, the plant will need closer to 40 to 60 days to fully mature. Harvesting the leaves early and frequently encourages the plant to produce more foliage, but taking too many leaves will inhibit the growth of the turnip root.
An effective harvesting technique is the “cut-and-come-again” method, where only the outer, larger leaves are picked, leaving the central growing point intact. Removing only a few outer leaves allows the plant to continue photosynthesizing and regenerating new growth, providing multiple harvests from a single plant.
The planting season ends when the ground freezes solid, making root extraction impossible, or when sustained summer heat above 80°F arrives. High heat causes the leaves to become tough and bitter.