Turnips are a versatile, cool-season crop appreciated for both their edible roots and their leafy greens. Each harvest requires specific timing to ensure peak flavor and texture. Knowing when to pull the root or snip the leaves is the difference between enjoying a mild, tender vegetable and encountering a tough, bitter one. The harvest window is relatively short, often spanning only a few weeks, making careful observation of the plant’s development important.
Key Indicators for Root Readiness
The most reliable gauge for turnip root readiness is the physical diameter of the bulb. For most common varieties, the optimal size for a tender, mild flavor is when the root reaches between two and three inches across. Harvesting at this stage prevents the root from developing the tough, fibrous consistency that occurs when they grow much larger.
A second visual cue, known as shouldering, signals that the root is actively swelling beneath the soil. Shouldering occurs when the top portion of the turnip pushes out of the ground, exposing the root crown to sunlight. For varieties like the ‘Purple Top White Globe,’ this exposed area takes on a characteristic purple hue, confirming that the root is ready for lifting.
Timing provides a general framework for when to start checking the roots. Turnips mature quickly, with most varieties ready for harvest approximately 30 to 60 days after the seeds were sown. Fall-planted crops often benefit from a light frost exposure, which converts starches into sugars, resulting in a sweeter root.
Harvesting the Greens
Turnip greens can be harvested much earlier than the root, often ready to consume within a month of planting, usually when the leaves are four to six inches tall. This early harvest is most successful utilizing the “cut and come again” method, which involves only snipping the outer, larger leaves from the plant.
It is important to leave the central growing point and at least two to three inner leaves intact to ensure the root continues to develop properly. The leaves are the plant’s photosynthetic engine, and removing more than about one-third of the foliage will stunt the growth of the underground root. Greens are most tender and mild when they are young, as older leaves develop a tougher texture and a stronger flavor.
Quality Degradation from Delayed Harvest
Leaving turnip roots in the ground past their ideal two-to-three-inch size compromises the quality of the harvest. Over-mature roots begin to accumulate lignin, a structural polymer that causes the interior flesh to become tough and woody. This excessive growth also concentrates the sulfur compounds within the root, leading to a strong, bitter taste.
A greater risk is the plant prematurely entering its reproductive stage, known as bolting. Bolting is triggered by environmental stress, such as temperatures above 75°F or extended periods of inconsistent watering. When a turnip bolts, it sends up a tall flower stalk, redirecting energy away from root development and toward seed production.
Once a turnip begins to bolt, the root immediately stops swelling and often remains small, woody, and unpalatable, while the leaves quickly turn bitter. To avoid this decline, gardeners should monitor the root size closely and pull the entire plant as soon as the optimal diameter is reached, especially as summer temperatures start to climb.