Potatoes are tubers, and the timing of their harvest significantly affects their quality, flavor, and ability to be stored. Knowing when to dig is based on visual cues from the plant, which indicate the stage of underground development. The decision depends on whether you seek tender new potatoes for immediate use or mature potatoes for long-term storage.
Harvesting Young Potatoes
New potatoes are small, immature tubers harvested early before the plant reaches full maturity. They are prized for their thin, delicate skins and waxy texture, making them ideal for boiling or roasting whole. Harvest can begin about two to three weeks after the plant starts to flower, signaling that small tubers have begun to form underground.
A gentle method for harvesting new potatoes involves carefully reaching into the soil at the base of the plant to remove a few tubers, leaving the rest of the root system undisturbed. Alternatively, you can carefully lift an entire plant, take the small potatoes, and replant the remaining portion to continue growing. Because their skin is fragile, new potatoes do not store well and should be consumed within a few days of being dug.
Indicators of Full Maturity
The signal that the main crop is ready for harvest is the natural death of the above-ground foliage, a process called senescence. The vines will begin to yellow, wither, and eventually collapse entirely. This dieback indicates that the plant has finished bulking up the tubers, which have reached their maximum size and physiological maturity.
After the foliage has completely died back, wait an additional 10 to 14 days before digging. This waiting period allows the potato’s skin to “set” or harden, thickening the outer layer. Skin set helps the tubers resist bruising, water loss, and disease during handling and storage. Harvesting immediately after the vines die results in thin-skinned, easily damaged potatoes that spoil quickly. Avoid harvesting when the soil is wet, as high moisture can compromise the integrity of the skin and cause rot.
Digging and Curing Potatoes
When digging, the process must be executed carefully to avoid damaging the mature tubers. Use a spade or garden fork and insert it several inches away from the plant’s main stem to avoid slicing or piercing the potatoes. Gently lift the entire clump of soil and tubers, sifting through the dirt by hand to locate all the buried potatoes. Any potatoes cut or bruised during harvest should be set aside for immediate consumption, as they will not store well.
After harvesting, the potatoes must undergo curing, which is separate from the in-ground skin setting. Curing heals minor scrapes and further thickens the skin, preparing the potatoes for long-term storage. This involves laying the potatoes out in a single layer in a dark space with moderate temperatures (ideally 50 to 60°F) and high humidity (around 85 to 95 percent). The curing process typically takes about two weeks before the potatoes are moved to a cool, dark storage location.