CORVALLIS, Ore. – Would you like to grow potatoes that stay fresh and store longer? Here are some research-based hints how to best harvest and store potatoes, from the Oregon State University Extension Service.
- Toughen up potatoes for storage before harvest by not watering them much after they flower. Let the vines die all the way back before you harvest them.
- Clean potatoes before storing them. You need only brush the soil off potatoes grown in coarse, sandy soil. But if you grow potatoes in fine, sticky clay soil, your potatoes may need washing. If so, be sure the potatoes are completely dry before placing them in storage.
- Cure newly dug and cleaned potatoes for a week to 10 days in moderate temperatures and high humidity and they will last longer. After digging them out of your garden and cleaning them off, store newly harvested potatoes where the temperature is about 65 degrees and the relative humidity ranges from 85 to 95 percent. Keep them under these conditions for a week to 10 days to harden off and heal any injuries caused during harvest.
- Sort out and cull injured and diseased spuds before storing them long-term. Once they are cured, sort the potatoes, putting the best ones in well-ventilated containers. Eat the ones hit by your shovel and the ones with bad spots or disease in the first month or so after harvest, as injured potatoes don't last as long. They also may spread spoilage or disease microorganisms to uninjured potatoes.
- Store your tubers in a cold, dark environment with moderate humidity. Store your best tubers in a dry room with constant temperature of 35 to 40 degrees and moderate humidity. Make sure to keep them dark, as light will turn them green and make them unfit for table use. Discard potatoes with an excessive amount of greening.
- Grow potatoes that keep well. Red potatoes don't keep as long as yellow or white varieties. Thin-skinned potatoes don't last as long in storage as those with thick skins, such as Russets.
Under these conditions, well-matured potatoes will stay in good condition for seven to eight months, said Alvin Mosley, retired OSU Extension Service potato researcher. When storage temperatures exceed 40 degrees, potatoes should keep for two to three months, but sprouting and shriveling may occur. If they sprout and shrivel, save them for planting in April.