Turnip greens are a popular, fast-growing cool-season crop valued for their tender, nutritious foliage. Cultivating them for greens, rather than roots, requires a specialized feeding approach focused on maximizing above-ground growth. Supplying the correct nutrients is essential for achieving a high yield of flavorful, deep-green leaves throughout the plant’s short life cycle.
Primary Nutrient Needs for Leaf Production
Since the goal is to maximize leaf harvest, the nutritional program must prioritize Nitrogen (N). Nitrogen is the fundamental component of chlorophyll, driving vigorous vegetative growth. A sufficient supply ensures the leaves are large, succulent, and have the desirable dark green color.
Phosphorus (P) and Potassium (K) play supporting roles in plant health. Phosphorus aids in early root development, anchoring the plant and facilitating nutrient uptake. Potassium regulates water movement, enhances overall plant vigor, and increases resilience against stress and disease.
Leafy greens require a high level of available nitrogen, skewing the NPK ratio toward the first number. The nitrate ($NO_3$) form of nitrogen is preferred for maximizing leaf yield. Fertilizers high in the ammonium ($NH_4$) form can reduce growth or lead to toxicity symptoms, making nitrate-based sources superior.
Optimal Fertilizer Types and Ratios
Fertilizer choice must reflect the high nitrogen requirement, favoring products where the first number in the N-P-K ratio is substantially greater than the others. Synthetic options include pure nitrogen sources like 15-0-0 (calcium nitrate) or high-N formulations such as 10-5-5 or 20-10-10. These deliver an immediate, concentrated dose to fuel rapid leaf expansion.
When using synthetic granular products, calculate the application rate based on the amount of actual nitrogen needed. A 100-foot row may require 0.5 to 1 pound of actual nitrogen throughout the season. For example, a 10-5-5 fertilizer contains 10% nitrogen by weight, meaning ten pounds of the product supplies one pound of actual nitrogen.
Organic growers can use natural sources known for high nitrogen content, which release nutrients slowly. Blood meal is a popular granular option, providing nitrogen as soil microorganisms break it down. Fish emulsion is a liquid alternative, offering a fast-acting dose absorbed quickly through roots and foliage.
Well-aged compost or manure, though lower in concentration, should be incorporated before planting. This builds a base of organic matter and provides slow-release nitrogen.
Application Timing and Frequency
The fertilization schedule begins before planting to establish a foundation in the soil. Before sowing, incorporate several inches of aged compost or a balanced fertilizer, such as 10-10-10, into the upper six to eight inches of the bed. This ensures phosphorus and potassium are available for root establishment and prepares the soil for moisture retention.
The main feeding regimen starts once plants are established, typically when seedlings are 3 to 4 inches tall or have their first true leaves. At this stage, apply the nitrogen-heavy fertilizer as a side-dressing. Side-dressing involves applying a band of granular fertilizer a few inches away from the plant row, avoiding contact with stems or leaves to prevent chemical burn.
Turnip greens are heavy feeders and benefit from light, frequent nitrogen applications. After the initial side-dressing, subsequent applications should occur every three to four weeks to sustain rapid leaf production. For continuous harvest, a quick-release liquid fertilizer, like diluted fish emulsion, can be applied every two to three weeks or after cutting to stimulate fresh growth. Always water thoroughly after applying granular fertilizer to move nutrients into the root zone.