Russet potatoes are cultivated for their high starch content and thick skin, making them ideal for baking and long-term storage. Achieving optimal storage quality depends entirely on harvesting the tubers at the correct stage of maturity. Improper timing results in thin-skinned potatoes prone to damage, disease, and rapid moisture loss during storage. The decision of when to lift the crop is based on the growth calendar and observable plant signals.
Timing for Different Harvest Goals
The appropriate harvest time for Russets is determined by the intended use of the crop. Harvesting “new potatoes” happens early, typically 60 to 70 days after planting, while the vines are still green. These young tubers have thin, delicate skins and a sweeter flavor profile. New potatoes are meant for immediate consumption and will not keep well for more than a couple of weeks.
In contrast, harvesting Russets for storage requires a much longer growing period, usually ranging from 90 to 120 days, or up to 135 days depending on the variety. This extended time allows the tubers to reach full size and maximize starch content. The primary goal of this later harvest is to ensure the development of a thick, hardened skin, which defends against spoilage.
To encourage skin development, growers often reduce or stop watering the plants one to two weeks before the anticipated harvest. Allowing the soil to dry out helps toughen the tuber’s outer layer, preparing it for successful long-term preservation.
Visual Cues for Full Maturity
The most reliable indicator that Russets are ready for the main storage harvest is the natural senescence, or dying back, of the foliage. The vines begin to yellow, eventually turning brown and papery as the plant redirects energy to the developing tubers. This process signals that tuber growth has ceased.
It is important to wait until the stems and leaves have completely died back and collapsed. However, the potatoes should not be dug immediately after the vines die. This waiting period, known as the “skin set” phase, is necessary for the skin to harden and firmly attach to the potato flesh.
This mandatory waiting period should last for two to three weeks after the foliage has died. To confirm maturity, a test dig can be performed on one or two plants. The skin of a mature, storage-ready Russet should not rub or slough off easily when gently rubbed.
If the skin peels off, the potatoes are still considered “new” and should be left in the ground to finish maturing. Harvesting before the skin is fully set significantly increases the risk of damage, moisture loss, and disease entry during handling and storage.
The Physical Process of Digging
The physical removal of the tubers should be done on a warm, dry day when the soil is not muddy or wet. Harvesting in dry soil minimizes the amount of dirt that adheres to the potatoes and reduces the potential for rot during handling. Excessive moisture on the tuber surface encourages spoilage.
To avoid slicing or bruising the crop, using a gardening fork or pitchfork is preferred over a spade or shovel. The technique involves pushing the fork into the soil well outside the perimeter of the main plant stem, typically 10 to 12 inches away. The fork is then used to gently lever and lift the entire plant and surrounding soil, revealing the potatoes.
All tubers should be handled with care to prevent bruising, as damaged potatoes do not store well. After lifting, gently brush off the majority of the loose soil, but do not wash the potatoes, as washing shortens their storage life. Harvested Russets must be immediately moved out of direct sunlight to prevent the skin from turning green, which indicates the formation of the bitter compound solanine.
Curing Russets for Storage
Once harvested, Russets intended for long-term preservation must undergo curing, a process separate from the time spent setting the skin in the soil. Curing is a specialized post-harvest treatment that heals minor scrapes or abrasions sustained during digging. This healing minimizes entry points for disease pathogens.
The process requires placing the potatoes in a dark, sheltered area with high humidity and moderate temperatures. Ideal curing conditions are a temperature range between 50°F and 60°F and a relative humidity of 85% to 95%. These conditions should be maintained for 10 to 14 days.
During this two-week window, the potato forms a protective layer, known as suberization, over damaged areas, effectively thickening the skin. This toughened skin significantly reduces moisture loss and extends the storage duration. Russet varieties, with their naturally thick skins, sometimes require the full two weeks to fully cure.
After curing is complete, the potatoes are ready for winter storage in a location that is cool, dark, and maintains high humidity. Optimal long-term storage temperatures are between 40°F and 45°F, which slows the tuber’s metabolic rate and prevents premature sprouting.