Check the plant tops: when they yellow, wilt, and die back, potatoes are usually ready
For new potatoes, harvest about 2 to 3 weeks after flowering
For mature potatoes, wait about 2 to 3 weeks after the vines have died back
Gently dig around one plant and inspect the tubers for size and skin firmness
Rub the potato skin with your finger; if the skin does not rub off easily, they are ready
Harvest before hard frost or prolonged wet weather
Stop watering once the tops begin to die back
If you want larger potatoes, leave them in the ground a little longer after the tops die back
If the tubers are exposed above the soil, harvest them right away
Harvest when the desired size has been reached for the variety you planted