I have been gardening for years. AlexH is correct, when the top of the plant dies, your potatoes should be ready to harvest. If you are not going to eat them right away, keep them in a dark, cool place. Potatoes will last a long time out of the ground as long as they are kept in a cool, dark place. I have a special spot for them out in my barn.When the green top dies - it's time to harvest![]()