Potatoes are a staple crop that home gardeners can cultivate successfully, beginning with the right preparation of the planting material. A seed potato is not a true botanical seed but is a tuber, a modified stem used for asexual propagation of the plant. Since planting a tuber produces a genetic clone of the parent plant, gardeners rely on certified seed stock to ensure a healthy start. Certified seed potatoes are subjected to rigorous inspection and testing to confirm varietal purity and guarantee they are free from systemic diseases and viruses that can dramatically reduce yields. Planting potatoes that have been chemically treated to inhibit sprouting, such as many found in grocery stores, or those that are not certified carries the risk of crop failure or introducing pathogens into the garden.
Preparing for Sprouting
The initial step in preparing seed potatoes is a process called “chitting,” which encourages the tuber to break dormancy and develop short, sturdy sprouts before planting. This pre-sprouting gives the potato a head start, potentially leading to an earlier harvest and a more vigorous plant once placed in the soil. To chit potatoes, place the tubers in a cool, bright, but frost-free location, such as an unheated room or garage, with temperatures ideally between 50°F and 70°F. The light is crucial, as it suppresses the formation of long, pale, and brittle sprouts that develop in darkness, favoring the growth of short, dark green or purple “chits” that are better suited for planting.
Position the seed potatoes with the end containing the most “eyes”—the small indentations where sprouts emerge—facing upward, often referred to as the “rose” end. Using an egg carton or a shallow tray with dividers can help keep the tubers stable and ensure adequate air circulation. Chitting typically takes between four to six weeks, and the tubers are ready for planting when the sprouts reach approximately 1/2 to 3/4 inch (1 to 2 centimeters) in length.
Dividing and Healing Tubers
Many larger seed potatoes can be cut into smaller pieces, or “sets,” to maximize the number of plants grown from the original stock. A general rule is to cut the tuber into blocky pieces, each weighing approximately 1.5 to 2 ounces, ensuring that every piece contains at least one or two healthy eyes or chits. Using a sharp, clean knife for this division is important to create a clean cut and minimize the risk of transferring pathogens between tubers.
After cutting, the freshly exposed surfaces must be allowed to “cure” or “callous” before planting. This prevents the sets from rotting in the cool, moist soil. This healing process involves letting the cut pieces sit in a dry, well-ventilated area, out of direct sunlight, for a period of one to three days. The cut surfaces will develop a protective, leathery layer that acts as a natural barrier against soil-borne diseases and excessive moisture loss.
Optimal Planting Conditions
Timing the planting correctly is important for success, with the general guideline being two to four weeks before the average last hard frost date in your region. The soil temperature should be at least 45°F to 55°F before planting to prevent the seed pieces from rotting in excessively cold or waterlogged conditions. Potatoes thrive in loose, well-draining soil that is rich in organic matter and slightly acidic, with an ideal pH range of 5.8 to 6.5.
To plant, dig a trench or individual holes about four to six inches deep, placing the seed pieces cut-side down with the sprouts pointing upward. Space the pieces about 10 to 12 inches apart within the row, leaving about 30 to 36 inches between rows to allow for subsequent hilling. Cover the seed sets with only two to three inches of soil initially, which leaves a partially filled trench that will be used for the first stage of hilling as the plants grow.
Post-Planting Maintenance
Consistent moisture is necessary immediately after planting, but the most distinctive post-planting task in potato cultivation is “hilling” or “earthing up” the plants. Hilling involves progressively mounding soil, straw, or compost around the emerging stems as they grow, and it is a technique that directly impacts yield and quality. The primary reason for this practice is to protect the developing tubers, which form along the buried stem, from exposure to sunlight.
Sunlight exposure causes a process called greening, where a toxic compound called solanine accumulates in the skin, making the potato bitter and potentially unsafe for consumption. Begin hilling when the plant stems reach about six to eight inches tall, drawing soil up around the base to cover about two-thirds of the stem, leaving only the top few leaves exposed. This process is repeated every two to three weeks as the foliage grows another six to eight inches, continuing until the plant begins to flower.
During the entire growing cycle, aim for one to two inches of water per week, especially once flowering begins and the tubers start to bulk up. Inconsistent watering can lead to misshapen or cracked potatoes. Fertilization should favor phosphorus and potassium over nitrogen, using a ratio such as 5-10-10, to promote tuber development rather than excessive foliage growth.