Potatoes (Solanum tuberosum) are like buried treasure in the garden. The green, leafy plants grow all summer but never give a hint at the bounty that lies around their roots. Although you can pick a few small new potatoes early in the season, the main cache continues to grow ever larger. Digging the main crop when it reaches its peak maturity results in an abundant harvest of potatoes that are well suited for storage. As a result, you can continue to enjoy your garden treasure through fall and into winter.
Dig into the side of the hill about 8 to 10 inches from the base of the potato plant to check for new potatoes, after the potatoes have flowered but while they are still green and leafy. Harvest any potatoes that are larger than a golf ball and then replace the soil over the remainder of the developing potatoes. New potatoes have thin skins and are only suitable for immediate use.
Allow the potato plants to yellow and die back before harvesting the main crop. Stop watering the plants when the vines begin to die so the potatoes can develop a tough skin. Potatoes mature enough for storage only after the vines die.
Loosen the soil on either side of the row of potato plants with a spading fork. Insert the tines of the fork into the soil and pull the handle backward so it lifts up the potatoes without piercing them. Pick the potatoes out of the loosened soil.
Brush the soil off the potatoes and spread them out in a dark 65 to 70 degree Fahrenheit location to cure for two weeks. Curing allows any cuts on the skins to heal, while the skins continue to toughen for better storage.