Preparing potatoes for planting is the initial step that determines the success of the harvest. This process involves waking the dormant potato tuber to ensure it develops strong sprouts before entering the soil. Proper preparation maximizes the number and size of the resulting potatoes. Taking these preparatory steps helps minimize the risk of soil-borne diseases that can devastate a crop. The careful handling of the seed piece improves the plant’s initial vigor.
Sourcing and Initial Preparation
The foundation of a healthy potato crop begins with the proper sourcing of planting material. It is recommended to use certified seed potatoes rather than common grocery store tubers. Commercial potatoes are often treated with sprout inhibitors, such as chlorpropham (CIPC), to extend shelf life, which severely hinders growth in the garden.
Certified seed potatoes are grown under specific field conditions and inspected to confirm they are free from common diseases like late blight and various viruses. Using uncertified material risks introducing pathogens into the garden soil, potentially affecting future crops for years. Once acquired, the seed potatoes need to be moved into an environment that signals the end of their dormancy period.
This initial preparation involves exposing the dormant tubers to warmer temperatures and light, which encourages the development of short, sturdy sprouts. This process, known as chitting, helps the potato get a head start on growth before it is placed underground.
Encouraging Sprouts (Chitting)
Chitting is the deliberate process of conditioning the seed potato to produce strong, healthy sprouts before planting. To achieve the best results, the tubers should be placed in an area that provides cool temperatures and exposure to indirect light. Ideal conditions are typically maintained between 50 and 60 degrees Fahrenheit (10–15 degrees Celsius).
The potatoes must be arranged in a single layer, often using shallow trays or egg cartons, with the end containing the most “eyes,” or growing points, facing upward. The presence of light suppresses the elongation of the sprouts, ensuring they remain compact and robust. These conditions encourage the plant to allocate its stored energy into developing multiple growth points.
Successful chits appear short, thick, and often exhibit a dark green or purplish pigmentation. If the sprouts grow long, pale, and fragile, it indicates that the environment was too warm or lacked sufficient light exposure. These weak, etiolated sprouts are easily broken off during handling and will not establish the plant as effectively.
Allowing the potatoes to chit for two to four weeks ensures that the stored starches are converted into energy for rapid initial growth once planted. This head start allows the plant to emerge quickly, making it more resilient to early season stresses. The development of multiple chits contributes to a higher yield by providing more stems from which new tubers can form.
Sizing and Protecting the Seed Pieces
Once the seed potatoes have developed strong, healthy chits, the next step is to prepare them for planting by cutting them into smaller pieces. Each individual piece should be approximately the size of a chicken egg, weighing between 1.5 to 2 ounces. Every cut piece must contain at least two well-developed eyes or chits to ensure successful growth.
When cutting the tubers, it is important to use a sharp knife that is frequently disinfected, perhaps with a dilute bleach solution, between potatoes. This practice prevents the mechanical transmission of any latent bacterial or fungal diseases. The large surface area of the fresh cut is a vulnerable entry point for pathogens once the piece is placed in moist soil.
To protect these fresh wounds, the cut seed pieces must undergo a curing or callusing process before they are planted. This involves spreading the pieces in a single layer in a warm, protected area with high humidity for two to three days. The ideal environment allows the cut surface to dry slightly but not desiccate entirely.
During this period, the potato forms a protective layer of cork cells, known as the periderm, over the exposed tissue. This tough, leathery skin acts as a natural barrier, reducing water loss and preventing soil-borne fungi and bacteria from entering the stored starch reserves. Planting uncured pieces often leads to rapid decay, especially in cool or wet soil conditions.