Rock:
I brought in the small potatos when I abandoned my straw-on-chain-link potato hill in November. I put them in a peach box and forgot them in the garage. It gets cold out there but never freezes. I looked at them a couple times over the winter and tossed out a couple of bad potatos, but did nothing else. It stays gloomy out there but is not totally dark. Along about Feb. they started sprouting and puttng out dry roots, got all shriveled. When I planted last week I looked at them and decided that they were good and lively, so planted them right along with the new store-bought seed 'taters.
Just hill up some of your May-planted potatos and let them winter.
Ox