The timing of a potato harvest is not a singular event but a deliberate choice that depends entirely on the intended use of the tubers. Potatoes are underground storage organs, and their quality—whether for immediate eating or long-term preservation—hinges on correctly reading the subtle signals from the plant above ground. Harvesting too early sacrifices size, while harvesting too late risks rot or pest damage. A successful harvest requires understanding the difference between a quick, early pull for thin-skinned delicacy and a patient wait for a hardened, storage-ready crop.
Timing the Harvest for New Potatoes (Early Crop)
“New potatoes” are young, immature tubers harvested while the plant is still actively growing, and they are prized for their tender texture and fresh flavor. These potatoes are ready to harvest approximately 7 to 8 weeks after planting, or about two to three weeks after the potato plant has finished flowering. The skin on these early potatoes is very thin and delicate, which means they should be consumed quickly and are not suitable for storage.
A common technique for harvesting a small batch of new potatoes is called “robbing the hill,” which allows the plant to continue growing. This involves gently reaching into the soil at the edge of the plant’s hill with your hands or a small trowel to remove only a few of the largest tubers. By carefully extracting the potatoes and leaving the root system intact, the remaining tubers can continue to mature. This method provides a fresh supply of small potatoes for summer meals without sacrificing the entire crop.
Signs of Maturity for Main Crop Potatoes (Storage)
Main crop potatoes are intended for long-term storage, requiring a different harvesting strategy. The primary indicator of readiness is the natural death of the foliage, a process known as senescence. Gardeners should wait until the plant’s vines and leaves turn completely yellow, then brown, and have fallen over naturally. This visual signal indicates the plant has stopped channeling energy into above-ground growth and has finished bulking the tubers underground.
To encourage the development of a thick, protective skin, it is helpful to cease watering the plants entirely once the foliage begins to yellow. Reducing the moisture in the soil signals to the plant that its growing season is ending, prompting it to “set” the skin. A mature skin is firmer, less prone to scuffing, and provides a barrier against disease and moisture loss during storage. If you dig up a test potato and the skin easily rubs off with your thumb, the tubers are still immature and need more time in the ground to finish hardening.
The Essential Steps After Vines Die Back (Curing and Digging)
After the vines have died back, a waiting period is necessary before digging begins. This final stage of “in-ground curing” allows the skin to set fully, preparing the tubers for storage. Waiting approximately two to three weeks allows the thin, immature skin to thicken and toughen, significantly extending the potato’s shelf life. This time also allows any minor abrasions or wounds to heal, minimizing the risk of rot during storage.
When the waiting period is complete, the physical harvest must be performed with great care to prevent damage that compromises storage potential. Use a garden fork, rather than a sharp shovel, and begin digging wide, well outside the expected location of the tubers to avoid piercing or bruising them. Potatoes typically grow just outside the original planting area, so lifting the entire clump gently is better than stabbing directly down into the hill. Once unearthed, the potatoes should be handled gently and immediately taken out of direct sunlight, which can cause them to turn green and develop a bitter, toxic compound called solanine.
The final step involves surface cleaning and a brief, warm-temperature curing process. Do not wash the potatoes, as excess moisture can encourage decay; instead, gently brush off any large clumps of soil. Spread the harvested tubers in a single layer in a dark, well-ventilated area (45°F to 60°F with high humidity) for about one to two weeks. This curing period enables the skin to fully cork or heal, allowing the potatoes to last for many months in cool, dark storage.