Growing potatoes successfully begins weeks earlier by preparing the seed tubers to sprout. This pre-sprouting process, often termed “chitting,” gives the plant a significant advantage by extending the effective growing season and promoting earlier tuber development. By encouraging the formation of short, strong, green shoots before planting, growers ensure the seed potato is ready for rapid growth once placed in the ground. This careful preparation is the foundation for a robust harvest.
Preparing Seed Potatoes for Planting
The initial step involves selecting firm, certified disease-free seed potatoes, which are preferable to store-bought varieties that may carry disease. To begin the chitting process, tubers should be placed in a light, cool, and frost-free location, with temperatures ideally around 50°F (10°C). Place the tubers in an egg carton or a shallow tray with the end containing the most “eyes,” known as the rose end, facing upward.
Exposure to light ensures the sprouts that emerge are short, sturdy, and typically green or purple, preventing the long, pale, and brittle shoots that develop in darkness. This pre-sprouting should begin approximately six weeks before planting to allow the shoots to reach about 1 inch (2.5 cm) in length. If the seed potatoes are large, cut them into pieces roughly 1.5 to 2 ounces in size, ensuring each segment contains at least one or two strong eyes.
After cutting, the pieces must be allowed to “cure” for a few days at room temperature until the cut surfaces form a tough, protective callus layer. This callus helps prevent the seed piece from rotting when planted into cool, moist soil. Planting whole, smaller tubers is also an option, as they do not require this cutting and curing step, minimizing the risk of disease transmission.
Selecting the Ideal Planting Site and Timing
Potatoes thrive in locations that receive full sunlight, requiring a minimum of six to eight hours of direct light daily for maximum growth and tuber formation. The soil must be loose, well-draining, and rich in organic matter to allow for easy expansion of the developing tubers. A slightly acidic soil pH is preferred, though potatoes can tolerate a range of conditions.
Timing the planting correctly is important. Planting must occur after the last expected hard frost, when the soil temperature has consistently warmed to at least 45°F (7°C). Planting too early in cold, wet soil can cause the seed pieces to rot. Because pre-sprouting accelerates growth, chitted tubers can be planted slightly earlier than unsprouted ones, which benefits regions with shorter growing seasons.
Planting Techniques and Essential Hilling
The chitted seed pieces should be planted into a prepared trench approximately 6 to 8 inches deep. Place the seed pieces with the sprouts facing upward, spacing them about 10 to 12 inches apart within the row. Cover them initially with only about 3 to 4 inches of soil, leaving the trench partially unfilled.
Watering is necessary, especially during the period when tubers begin to form, which often coincides with the plant’s flowering stage. Aim for about 1 to 2 inches of water per week, but the soil should never become waterlogged. The partially filled trench allows for the maintenance practice known as “hilling” to begin once the plant shoots emerge.
Hilling involves drawing soil or organic material, such as straw, up and around the stems of the growing plant. This technique serves two primary functions. The first is to prevent developing tubers from being exposed to sunlight, which causes them to turn green due to the production of solanine, a bitter and slightly toxic compound.
The second function is to encourage the plant to form more tubers along the buried stem. Potatoes form on specialized underground stems called stolons; covering the main stem with soil stimulates the growth of more stolons, resulting in a larger harvest. Hilling should be done when the plant stems are about 6 to 8 inches tall, covering all but the top few inches of foliage. Repeat this process periodically, adding more material each time the plant grows another 6 to 8 inches, until a mound of soil is built up around the base.
Harvesting and Curing the Crop
The time for harvesting is determined by the intended use and the plant’s natural life cycle. For “new potatoes,” which are small and thin-skinned, harvesting can begin about seven to eight weeks after planting, often around the time the plant is flowering. Digging gently beside the plant allows the removal of a few tubers while leaving the main plant to continue growing.
For a mature crop intended for long-term storage, the harvest is delayed until the vines naturally turn yellow and die back completely. This signals that the tubers have finished growing and their skins have begun to set and thicken. A simple test for maturity is rubbing the skin of a freshly dug tuber; if the skin remains firmly attached, the potato is ready for harvest.
After harvesting the potatoes with a spading fork, taking care to avoid cuts and bruises, gently brush them clean of excess soil but do not wash them. The tubers then need to be “cured” for one to two weeks in a dark, well-ventilated space with high humidity (85 to 95 percent) and a moderate temperature of 50°F to 60°F. This curing period allows minor wounds to heal and the skin to toughen, which improves the potato’s ability to store long-term.