You need:
any number of buckets (old Rooster buckets are suitable) with the bottoms CUT OFF! Then you need small black plastic bin bags, lots of compost (from your own midden and mixed with a bit of potato or any high potash fertilizer) and a clean piece of ground levelled off and covered with weed suppressing membrane if you like.
Now, if you want to avoid weeds, lay membrane and cut a cross in it to go under the bucket. Sit the bucket on top, line with bin-bag and punch a few fork-holes in it so the roots can get through to the soil below. Fold the top of the bag over the outside of the bucket into a deep cuff. Plant a potato in about 8" of compost. Watch it grow and earth up with more compost until the haulm reaches the top. In this way the roots can reach the soil for moisture but the spuds themselves form inside the bucket. With maincrop types, when airborne blight spores threaten, unfold the cuff of bin bag to make a tall collar which protects the foliage from the blight spores (support it with slim canes pushed around the outside of the bucket if necessary).
When the foliage dies back, cut it off and tie off the neck of the bin back and leave the whole thing to ripen for 10 to 14 days (NO MORE or you'll get mould) by which time the compost has dried out and the skins of the spuds have thickened a bit. Now you have a nice clean crop of ripened maincrop potatoes that will store all winter. You can use the same piece of ground again next year (because this technique avoids cross infection) and although it's a bit of trouble, it means you really will have blight-free main crop potatoes to store.
Incidentally, wood-based cat litter (pellets that dissolve to sawdust when the cat pees on them) are perfect for storing your maincrops. If one goes rotten and weeps, the litter dissolves and soaks away the moisture so you can remove the offender and the dust, knowing that the infection has been isolated from the rest of the crop. You can use the pellets for the same purpose year after year. (so it's not as expensive as it seems in the long term).
It takes a while to assemble all the bottomless buckets you will need to do this but good luck with it, it definitely works (that's why about half our plot-holders do it) but not really necessary for first and second earlies. This is the technique for those big fat bakers you want to last in their boxes or sacks until March.
