Plant after the danger of frozen soil is past. In Zone 5 you should be able to plant mid-April because the plants start to show up at the beginning of May. Potatoes do best in temperatures between 16 and 26°C (61 to 79°F). This is all also a matter of what variety you plant.

Proper Harvesting

When the plant has turned yellow/brown the foliage is removed and then there is a waiting period of 14 days to ensure the wounds on the potatoes heal and the skin matures. Any longer and you run the risk of fungus, pests, worms etc. Storage After harvesting, the best way to store potatoes is to keep them in wooden crates that have been lined with newspaper and then covered with newspaper. The temperature should remain between 4-8°C (39-46°F) and the air humidity 90%! Any less and the humidity will cause the potatoes to shrink/shrivel. Potatoes can be stored in earth as that also holds water, but they should not be wet as that of course encourages fungus. \

Adding Ethylene

I was able to talk with an expert from the Potato Advisory Service in Heilbronn, Germany. He informed me that adding ethylene does play a role in inhibiting sprouting, however it only works in commercial storage where the atmosphere can be controlled and the gasses cannot leak out. Using apples in home storage does not provide enough ethylene (should be a constant 10 ppm) to prevent the sprouting, but is enough to actually encourage sprouting!

Replanting

As to the question about the removal and planting of the roots and sprouts on a potato. He said you should cut about 1.5 cm (0.6 inches) to go with it. At that it will take longer to grow than using the whole potato, but it will grow.

He also shared that during the war, people would plant the potato peelings and that worked, too. It just takes longer.