Harvesting homegrown potatoes requires precise timing and careful post-harvest handling. Employing the correct techniques for digging and preparation maximizes the yield and prevents spoilage, ensuring the stored harvest remains usable for many months.
Knowing When to Harvest
The decision to harvest depends on the intended use, distinguishing between immature “new potatoes” and mature “storage potatoes.” New potatoes are ready relatively early, often 7 to 8 weeks after planting or shortly after the plants begin to flower. These delicate tubers have thin skins, making them delicious for immediate consumption but unsuitable for long-term keeping.
For storage, a thicker, hardened skin is necessary, requiring the plant to complete its life cycle. The primary visual cue for mature potatoes is the complete dieback of the foliage, or haulms. Once the vines have fully died back, leave the potatoes in the ground for an additional two to four weeks for “skin set.” Withholding water for about two weeks before the final harvest helps the skin set and prepares the tubers for digging in drier soil.
The Physical Digging Process
Removing potatoes from the soil must be approached with care to prevent nicks and bruises that compromise storage life. A garden fork or a specialized potato digger is preferable to a standard shovel, as the tines are less likely to slice through the tubers. Wounds created by cutting or bruising allow pathogens to enter, leading to rot in storage.
Insert the digging tool a safe distance away from the main stem, typically 6 to 12 inches out, to avoid piercing the cluster of tubers. Gently lever the tool to lift the entire mass of soil and potatoes, then carefully sift through the loosened dirt by hand to locate all the scattered tubers. Harvesting should always be done on a dry day, as wet soil increases the risk of fungal or bacterial infection during handling. Any potatoes that are accidentally sliced or significantly bruised should be set aside for immediate use, as they will not store successfully.
Curing Potatoes After Harvest
Curing prepares mature potatoes for an extended storage period. This process heals minor scrapes, abrasions, and skinning that occurred during digging. A cork-like layer forms over minor wounds through suberization, which reduces moisture loss and limits the entry points for decay organisms.
Optimal conditions for curing involve placing the potatoes in a dark location with a moderately warm temperature, ideally between 50°F and 60°F, for one to two weeks. Maintaining high humidity (85% to 95%) is necessary to prevent the tubers from shriveling while the skin heals. Placing the potatoes in a single layer on a screen or newspaper in a well-ventilated area ensures sufficient airflow around each tuber.
Preparing Potatoes for Storage
Once the curing period is complete and the skins are firm, the potatoes are ready to be moved to a permanent storage environment. Long-term storage requires a location that is cool, dark, and moderately humid to drastically slow the tubers’ metabolic processes. The ideal temperature range for table potatoes is approximately 37°F to 45°F, which minimizes sprouting while preventing the starches from converting into undesirable sugars that affect flavor.
The storage area must be completely dark, as exposure to light will cause the potatoes to develop chlorophyll and a green tint. This greening is accompanied by the formation of solanine, a bitter-tasting alkaloid that can be toxic in large amounts. High humidity (85% to 95%) must be maintained to prevent the potatoes from dehydrating and becoming wrinkled and soft. Store the potatoes in breathable containers like burlap sacks or wooden crates, and keep them away from ethylene-producing fruits and vegetables, such as onions and apples, which accelerate sprouting.