The potato is a starchy, underground tuber. Determining the optimal time for lifting the tubers from the soil is crucial for maximizing the harvest. Correct timing directly influences the overall yield, the texture and quality of the potatoes, and their ability to be stored long-term.
Harvesting Timing for New Potatoes
New potatoes are harvested early in the plant’s development cycle, before they reach full mature size. They are prized for their delicate, moist texture and fresh flavor, making them suitable for immediate eating. Their skin is characteristically very thin and can be easily rubbed off.
The ideal window for harvesting new potatoes begins shortly after the plant starts to flower, usually two to three weeks after the first blossoms appear. Digging a test hill confirms the tubers are of a desirable size, typically ranging from a golf ball to a small hen’s egg. Harvesting at this stage interrupts the skin-setting process, which keeps the outer layer thin.
Recognizing Maturity for Storage Potatoes
Potatoes intended for long-term storage require a different approach, focusing on allowing the tubers to fully mature underground. The visual cue signaling maturity is the complete yellowing and dying back of the foliage, often called the haulms. When the above-ground growth withers, the plant diverts energy into thickening the tuber skin below.
It is necessary to leave the potatoes in the soil for a specific waiting period after the foliage has died completely. This period, lasting approximately two to three weeks, is known as the “skin-set” phase. During this time, the tuber skin toughens and adheres firmly to the flesh. A properly set skin is more resistant to scuffing, bruising, and disease, resulting in longer storage life.
Harvesting before the skin has fully set can result in “skinning,” where the outer layer peels off easily, leaving the underlying flesh exposed and vulnerable to decay. Monitoring the tops is important, as forcing the plant to stop growth—sometimes done by cutting the haulms—can accelerate this necessary setting phase. This intentional delay allows the periderm layer, the protective outer tissue, to fully mature, which preserves the potato over months.
The Physical Harvesting and Curing Process
Once the necessary underground waiting period is complete, harvesting must be executed with precision to prevent damage to the mature tubers. The first step involves carefully locating the approximate position of the potatoes, which typically radiate outward from the central stem. Using a garden fork or a blunt-tipped shovel is recommended, as sharp tools can easily pierce the tubers.
The tool should be inserted into the soil a safe distance away from the main stem, generally about 12 to 18 inches, to avoid direct contact with the buried crop. The goal is to gently loosen and lift the entire cluster of soil and tubers rather than attempting to spear individual potatoes. This technique minimizes mechanical wounds, which are entry points for rot and mold during storage.
Careful handling is required throughout the lifting and collection process. Tubers should not be thrown or dropped into containers, as minor impacts can cause internal bruising that leads to rapid spoilage. Brush off only the largest clumps of soil, leaving the finer dirt on the skin, and avoid washing the potatoes at this stage.
Following the harvest, the potatoes must undergo a deliberate curing process before being moved into storage. Curing involves placing the tubers in a dark, well-ventilated space with high humidity and temperatures between 50 and 60 degrees Fahrenheit. This environment encourages minor scrapes incurred during harvesting to heal over, forming a protective cork layer.
This curing period typically lasts for one to two weeks and acts as a final defense mechanism against pathogens. After curing is complete, the potatoes are ready to be transferred to a cooler, dark environment, such as a root cellar, where they can be held for several months.