Planting potatoes successfully requires setting the seed piece, or “eye,” at the proper depth. This initial placement influences the plant’s emergence, protects it from environmental stresses, and determines the quantity and quality of the harvest. Correct planting depth and spacing provide a stable environment for the developing root system and maximize yield.
Preparing Seed Potatoes for Planting
Certified disease-free seed potatoes should be selected, as using grocery store potatoes may introduce disease or be treated with sprout inhibitors. A week or two before planting, the tubers should be exposed to light and temperatures between 60 and 70 degrees Fahrenheit to encourage “chitting,” which is the development of sturdy, short sprouts.
If the seed potato is larger than a chicken egg, it can be cut into smaller pieces. Each piece should weigh approximately 1.5 to 2 ounces and contain at least one or two well-developed eyes. After cutting, the pieces must be allowed to “cure” or callus over for one to three days in a warm, well-ventilated location away from direct sunlight. This curing process forms a protective layer over the cut surface, which significantly reduces the risk of the seed piece rotting in the cool, moist soil before it can sprout.
Determining the Ideal Planting Depth and Spacing
The optimal initial planting depth for seed potato pieces is typically in a trench between 4 and 6 inches deep, with the cut side facing down and the eyes pointing upward. This depth ensures the seed piece is adequately protected from light exposure and temperature fluctuations, including late frosts, which can damage the emerging shoots. In heavier or clay-rich soils, a slightly shallower depth of about 3 inches may be necessary to allow the plant to emerge more easily.
The soil should be loose, well-draining, and rich in organic matter to allow for proper tuber development and expansion. A distance of 10 to 15 inches between individual seed pieces within the row is generally recommended, as this provides sufficient room for each plant to develop a substantial set of tubers. Rows should be spaced 2 to 3 feet apart to allow for proper air circulation and to provide ample space for the subsequent hilling process.
Managing Growth Through Hilling
The relatively shallow initial planting depth is compensated for by a subsequent practice known as hilling, which is the mounding of soil around the growing plant stems. Hilling is a necessary step because the new tubers, which are modified stems, form along the underground portion of the stalk. If these developing tubers are exposed to sunlight, they begin to produce chlorophyll, causing them to turn green, and they also synthesize glycoalkaloids, primarily solanine, which is a mildly toxic compound.
The first hilling should occur when the potato plant stems have reached a height of 6 to 8 inches above the ground. Soil is carefully drawn up from the sides of the row and mounded around the base of the plant until only the top few inches of foliage are exposed. This process is repeated periodically as the plant grows, burying the stems and encouraging the formation of more tubers along the covered stalk. Hilling shields the tubers from light to prevent greening and solanine production, provides structural support, and increases the overall yield by creating a longer stem section for tuber formation.