Harvesting and storing potatoes properly are interconnected phases that determine the quality and longevity of the crop. A successful yield depends on careful handling during digging and precise environmental control afterward. Mishandling tubers at either stage significantly reduces shelf life, often leading to premature spoilage or sprouting. Understanding the specific requirements for harvest timing and post-harvest preparation ensures the maximum amount of potatoes can be enjoyed throughout the winter.
Timing the Harvest
The decision of when to harvest depends on whether the goal is to obtain “new potatoes” or tubers intended for long-term storage. New potatoes are typically smaller, have thin skins, and are ready much earlier in the season while the foliage is still green and actively growing. These immature potatoes are delicious immediately but will not keep for more than a few weeks due to their delicate skin structure.
Potatoes meant for winter storage require full maturity, which is indicated by the plant’s foliage naturally yellowing and completely dying back. Many growers proactively cut the vines down to the soil level, then wait an additional two to three weeks before digging. This waiting period allows the potato’s skin to thicken and toughen, a process known as “setting the skin.”
To confirm maturity, perform a simple “skin set” test on a few sample potatoes. Gently rub the skin with a thumb; if the skin easily peels away, the tubers need more time underground. A properly set skin will resist peeling, confirming the potato is prepared for long-term dormancy. Harvesting before this point results in easily damaged tubers susceptible to rot.
Digging Up and Curing
Once the skin is properly set, removing the tubers from the ground must be done with extreme care to prevent bruising or cuts. Use a garden fork rather than a shovel, as the tines are less likely to slice the potatoes. Begin digging well away from the center of the original plant, moving outward in a circle to locate the tubers.
Damage most commonly occurs when the potato is accidentally pierced or sliced, creating an entry point for pathogens. Any potato that is visibly cut or bruised should be set aside for consumption within the next few days, as it will not store successfully. Gentle handling is paramount, as minor impacts can compromise the tuber’s integrity.
If the weather is dry, harvested potatoes can be left on the soil surface for a few hours after digging. This brief exposure helps surface moisture evaporate and allows the skin to firm up slightly. Afterward, the potatoes should be brought indoors to begin the post-harvest preparation known as curing.
Curing is a mandatory, short-term process designed to heal minor abrasions and further thicken the skin before long-term storage. This stage requires a warm environment, typically between 50°F and 60°F (10°C and 16°C), coupled with high humidity, around 85% to 95%. This combination encourages the tubers to repair themselves by forming a protective layer of cork cells, or periderm, over small wounds.
This wound-healing response significantly reduces the risk of moisture loss and pathogen entry during dormancy. The curing process usually takes ten to fourteen days to complete successfully. During this time, the potatoes should be kept in complete darkness and arranged in a single layer to ensure air flow. Once the skins feel firm and noticeably hardened, the potatoes are ready to transition to the cooler conditions required for long-term dormancy.
Creating the Ideal Storage Environment
The focus shifts to maintaining the precise environmental conditions necessary for long-term dormancy. Successful storage relies on controlling three primary factors: temperature, humidity, and light exposure. The storage location must be consistently cool, ideally maintained between 35°F and 40°F (2°C and 4°C).
This low temperature significantly slows the metabolic rate of the tubers, inhibiting sprouting and minimizing weight loss. Temperatures much lower than this range risk causing starches to convert to sugars, resulting in an undesirable sweet flavor known as cold-induced sweetening. Maintaining high relative humidity (85% to 95%) is equally important to prevent the potatoes from drying out and shriveling.
Complete darkness is essential for long-term storage, as any light exposure triggers the production of chlorophyll and solanine near the surface. Solanine is a natural glycoalkaloid that causes the potato skin to turn green and renders the tuber bitter and potentially toxic. The storage area should be fully enclosed and shielded from all sources of illumination to maintain safety and quality.
Potatoes should be stored in containers that allow for adequate air circulation, preventing the buildup of heat, ethylene gas, and moisture that encourages fungal growth and rot. Suitable containers include burlap sacks, slatted wooden crates, or perforated plastic bins that allow gases to escape. Avoid storing potatoes in non-breathable plastic bags or airtight containers, which trap moisture and accelerate decay.
Stored potatoes should be periodically inspected, perhaps once a month, throughout the winter storage period. Any potato showing signs of softening, shriveling, or developing mold must be immediately removed from the batch. This preventative maintenance is essential because a single rotting tuber can release spores and gases that quickly contaminate and ruin the entire stored supply.