Potatoes are a staple crop often grown from pieces of the tuber itself, maximizing the number of plants from a limited supply of starter material. These starter tubers are known as “seed potatoes,” and cutting them allows a single potato to yield multiple “seed pieces.” Each seed piece is a block of tissue containing at least one or two viable growth buds, or “eyes,” which will sprout to form a new plant. This method requires proper preparation to ensure the cut sections successfully grow rather than rot in the soil.
Preparing the Seed Pieces
The process begins with using certified seed potatoes, which are guaranteed to be disease-free and are much safer than planting store-bought potatoes that may carry viruses or have been treated with sprout inhibitors. To create the seed pieces, the large tubers should be cut into blocky chunks, with each piece weighing between 1.5 and 2.5 ounces. It is important to ensure that every resulting chunk contains a minimum of one to two distinct “eyes,” which are the indentations from which the plant’s sprouts will emerge. A clean, sharp knife should be used for cutting to minimize tissue damage and prevent the spread of any potential pathogens.
After cutting, the seed pieces must undergo curing or callousing, a step many first-time growers overlook. This involves laying the pieces out in a dry, airy place away from direct sunlight for two to three days. The goal is for the exposed tissue to form a tough, protective layer, known as suberization. This hardened layer seals the cut surface, preventing the entry of soil-borne diseases and minimizing moisture loss once the piece is planted.
Site Preparation and Timing
Before planting the cured seed pieces, the location and soil conditions must be optimized to support the potato’s unique growth cycle. Potatoes require a location that receives full sun exposure, meaning at least six hours of direct light daily, with eight to ten hours being preferable for robust growth. The soil itself should be loose, well-draining, and rich in organic matter to encourage proper tuber development and prevent misshapen potatoes. Potatoes thrive in slightly acidic soil conditions, with an ideal pH range falling between 5.0 and 6.5.
Timing is determined by the soil temperature, which needs to be at least 45 degrees Fahrenheit for the seed pieces to begin growing. For rapid and sustained growth, the soil temperature should be closer to 50 to 55 degrees Fahrenheit. Planting into soil that is too cold or waterlogged risks the seed pieces rotting before they can sprout, even if planted two to four weeks before the last spring frost. Avoid planting in ground that has recently received nitrogen-heavy fertilizers or fresh manure, as high nitrogen promotes excessive leafy growth at the expense of tuber formation.
The Physical Planting Steps
Once the soil is prepared and the seed pieces are cured, planting begins by digging a shallow trench or individual holes. A common method is creating a trench four to six inches deep, which allows for the subsequent hilling process. The depth may be shallower in heavy clay soils or deeper in light, sandy soils to account for drainage and moisture retention. The seed pieces are then positioned within this trench, paying careful attention to their orientation.
The cut side of the seed piece should face down onto the soil, with the eyes or emerging sprouts facing upward. This positioning encourages efficient growth, directing roots downward and shoots upward. Seed pieces should be spaced 10 to 15 inches apart within the trench, with rows separated by 24 to 36 inches to allow adequate space for hilling. The final step is covering the seed pieces with only three or four inches of soil, leaving the trench partially unfilled and ready for the first stage of hilling.
The Critical Role of Hilling
Hilling is a mandatory practice for successful potato cultivation, affecting both the quantity and quality of the harvest. This technique involves mounding additional soil, compost, or straw around the base of the growing plant stems as they increase in height. The first hilling should occur when the young plants reach a height of six to eight inches above the ground. This process must be repeated every time the plant grows another six to eight inches until the foliage begins to flower.
Hilling serves the dual purpose of increasing yield and preventing toxicity in the developing tubers. Potatoes form on underground stems called stolons; burying the main stem encourages the formation of more stolons, resulting in more potatoes. The second function is to block sunlight from reaching the tubers, which grow near the soil surface. Exposure to light triggers the potato to produce solanine, a toxic compound that causes the tuber to turn green and become unsafe for consumption.