Growing potatoes requires understanding the precise timing needed for success in the New England climate. Achieving a good harvest depends on localized environmental factors, particularly the temperature of the soil where the tubers develop. For Massachusetts gardeners, aligning planting with warming spring conditions is the first step toward a bountiful yield. This guide details the process, from finding the right moment to placing the seed potatoes in the ground through to harvest.
Determining the Right Planting Window
The optimal planting time in Massachusetts is a window determined by soil warmth, not a fixed date. Although potatoes are a cool-season crop, the soil must be warm enough to prevent the seed pieces from rotting before they sprout. The minimum acceptable soil temperature is 40°F, but the ideal range for rapid growth and wound healing is between 45°F and 50°F.
Gardeners should typically aim for planting between late March and May, depending on their specific location and microclimate. Eastern areas of the state often experience soil warming earlier than the cooler, higher-elevation regions of Western Massachusetts. Planting is often recommended two to four weeks before the last expected frost date, as emerging shoots can tolerate a light frost.
Focusing on the soil temperature, measured four inches deep, provides a more accurate cue than air temperature alone. Planting too early into cold, saturated soil significantly increases the risk of the seed potato decaying before germination. The choice of potato variety also influences the timeline, as early-season types mature more quickly than maincrop types.
Essential Preparation Steps
Before planting, “chitting” gives seed potatoes a head start by encouraging sprout formation. This involves placing them in a light, cool, and frost-free location, such as a windowsill, for four to six weeks before planting. Exposure to light ensures the resulting sprouts are short, sturdy, and dark, making them less likely to break off during planting.
Larger seed potatoes should be cut into pieces roughly the size of a chicken egg, ensuring each piece contains at least one or two “eyes.” After cutting, the pieces should be left in a cool, humid space for a day or two to form a protective, cork-like layer called a callus. This callusing helps prevent rot and disease organisms from entering the seed piece once it is planted.
Potatoes thrive in a well-drained, loose, and deep loam. Amending the soil with organic matter, like compost, improves texture, but fresh manure should be avoided as it can promote potato scab. Potatoes prefer a slightly acidic soil pH, ideally between 4.8 and 5.5, which naturally suppresses the development of potato scab.
Planting Techniques for Optimal Yield
The standard method involves digging a shallow trench, typically four to six inches deep. The prepared seed pieces, with the eyes facing upward, should be placed in the trench, spaced 10 to 12 inches apart for maincrop varieties. Rows should be spaced 30 to 36 inches apart to allow space for hilling. The seed pieces are initially covered with only three to four inches of soil, leaving a partial trench.
The critical technique for maximizing yield is “hilling,” the gradual mounding of soil around the emerging plant stems. Hilling protects the developing tubers, which form along the underground stem, from sunlight exposure that causes them to turn green and toxic.
Hilling should begin when the plant reaches six to eight inches tall, with soil gently drawn up around the stems until only the top few leaves are visible. This process is repeated two to three times as the plant grows, ultimately creating a mound 12 to 18 inches high. This continual mounding encourages the plant to produce more underground stem, leading to a greater number of tubers.
Maintenance and Harvesting Timeline
Consistent moisture is necessary throughout the growing season, especially when the plants are flowering and tubers are rapidly expanding. Watering should be done at the base of the plant to keep the foliage dry, minimizing the risk of common fungal diseases like late blight. Regular monitoring for pests, such as the Colorado potato beetle, is essential to maintain healthy leaf growth.
The harvest timeline depends on the intended use of the potatoes. For “new potatoes,” which are small, thin-skinned, and best for immediate consumption, harvesting can begin two to three weeks after the plant flowers, typically 60 to 70 days after planting. These are carefully dug from the sides of the hill, allowing the main plant to continue maturing.
For mature, storage-ready potatoes, the foliage must be allowed to completely die back, either naturally or induced by the first hard frost. This signals that the tubers have reached full size and the skins have thickened, a process taking 90 to 120 days for most maincrop varieties. After digging, the potatoes should be “cured” in a dark, humid space at 45°F to 60°F for one to two weeks to heal minor injuries and prepare them for long-term storage.