Potatoes can be harvested depending on their variety and maturity stage:

• Early potatoes can be harvested as early as mid-June.
• Second early varieties are ready around July and August.
• Maincrop potatoes are usually harvested from late August to October.
• The best time to harvest maincrop potatoes is when the leaves turn yellow and die back. After cutting off the top growth, wait about 10 days before digging the tubers.
• Baby or new potatoes can be harvested about 7-8 weeks after planting when they are 1-2 inches in diameter.
• Flowering of potato plants also signals that new potatoes can be harvested soon after the flowers fall off.
• For maximum storage life, wait until the potato plants have fully died back and their foliage has browned before harvesting.
• Potatoes are generally ready to harvest 55-120 days after planting depending on variety, with early potatoes maturing between 55-70 days and late maincrop varieties taking 90-120 days.

In summary, harvesting potatoes can span from mid-June until October or even later depending on the variety and local climate. Early potatoes are harvested sooner for fresh use, while maincrop potatoes can be stored for several months when harvested later after the plants die back.