The potato, a staple crop globally, is botanically known as Solanum tuberosum. Determining the correct harvest time is not a single date, but a variable window influenced by the specific variety, intended use, and regional climate. Unlike above-ground vegetables, the readiness of a potato is not immediately visible. Growers must observe both the plant’s life cycle and the tuber’s physical characteristics to maximize yield and quality.
New Potatoes Versus Storage Potatoes
The initial decision a grower makes is whether to harvest the crop early for immediate consumption or to wait for full maturity to allow for long-term storage. These two goals define the earliest and latest possible harvest windows. New potatoes, which are small, tender, and generally 1 to 2 inches in diameter, are typically ready for harvest much sooner, usually between 60 and 80 days after planting. The plants are still green and actively growing when these “baby” potatoes are pulled from the soil.
These early-harvested tubers have thin, delicate skins that rub off easily, making them unsuitable for extended storage. They should be eaten within a few days of harvest. Full maturity for storage potatoes, often called maincrop varieties, takes significantly longer, ranging from 90 to 120 days or more after planting. This extended time allows the tubers to swell and develop a thick, durable skin, enabling them to be cured and kept for several months.
Regional Timing Differences
The calendar months for potato harvest shift dramatically based on the local climate and the threat of frost. In cooler regions, such as the Northern United States, the planting season begins in late spring, typically April or May, after the last hard frost. This timing pushes the main harvest season for mature, storage potatoes into late summer and early autumn, most commonly August or September.
Warmer regions, particularly in the Southern United States, have a much broader growing window, sometimes allowing for multiple plantings in one year. Growers in these areas may plant an early spring crop for a mid-summer harvest, or a fall crop for a late-season or winter harvest. Across all regions, the primary concern remains the soil temperature. Planting must be avoided when the ground is too cold or too wet, which can cause the seed potato to rot.
Physical Signs of Harvest Readiness
For a mature, storage-ready crop, the most reliable indicator of readiness is the natural dieback of the plant’s foliage, a process called senescence. The leaves and stems, or vines, will turn yellow, then brown, and eventually wither and collapse to the ground. This visual cue signals that the plant has completed its growing cycle and has redirected its energy back into the tubers underground.
Once the vines have died back, growers often wait an additional 10 to 14 days before digging, a waiting period that is important for the final development of the skin. This process is confirmed by performing a simple rub test on a sample potato. If the skin adheres firmly and resists being rubbed off by a thumb, the tuber is mature and the skin is fully “set” for storage. If the skin sloughs off easily, the potato is still immature, and the remaining crop should be left in the ground for another week to toughen up.