Potatoes are grown through vegetative propagation, an asexual method using a part of the parent plant to grow a genetically identical clone. The small indentations on the potato surface, called “eyes,” are dormant buds or nodes on the underground stem (tuber). These buds contain all the necessary genetic material to sprout new shoots and establish a complete new plant.
Preparing the Seed Potatoes
Selecting and preparing certified disease-free seed potatoes ensures a strong start and prevents disease. Small seed potatoes, about the size of a chicken egg, can be planted whole. Larger seed potatoes should be cut into pieces roughly one to two inches square.
Each cut piece must contain at least two to three healthy eyes to provide enough growing points and energy for a viable plant. Allow the cut pieces to rest in a cool, well-ventilated area for one to two days before planting. This resting period allows the cut surfaces to form a protective layer, known as callusing or curing. Curing helps reduce the risk of rot and disease infiltration once the pieces are planted in moist soil.
Proper Orientation: Eyes Up or Down?
The definitive guidance is to position the seed potato piece with the majority of the eyes facing upward. The eyes are the growth points from which the main shoots will emerge. These stems naturally grow toward the sunlight, a biological response known as phototropism.
Planting the eyes facing up allows the emerging shoots to grow directly toward the soil surface, minimizing the energy and time required for the plant to break ground. If the seed piece is planted upside down, the shoots must grow downward first, then curve upward, which delays emergence and expends valuable stored energy. For cut seed pieces, place the callused surface face-down in the soil, with the eyes pointing upward.
Essential Planting Depth and Spacing
Planting the prepared seed pieces at the correct depth and spacing creates the best environment for tuber development. Dig a trench or hole approximately four to six inches deep in loose, well-draining soil. Place the seed pieces with the eyes facing up, spacing them about 10 to 15 inches apart within the row.
This spacing ensures each plant has adequate room to develop its root system and produce multiple new tubers. A primary practice in potato cultivation is “hilling,” which involves mounding soil up around the growing stems as the plant reaches eight to ten inches in height. Hilling is necessary because new potatoes form along the underground stem, and covering them maximizes the growing area. Hilling also prevents sun exposure, which causes potatoes to turn green and produce solanine.