I just use heavy plastic sacks for first earlies - roll the sack down punch a few holes for drainage, put in about 4" of soil
compost whatever, then add 3 seed potatoes cover with compost . Keep topping up the bag unrolling it as you go. Harvest by removing potatoes without killing the plant
you can just buy a bag of compost open one end roll the top so it stays open push in 3 seed tubers and leave - no topping up or anything 1st and 2nd earlies will yield well, and can be harvested as they grow . I get the bags of compost for free from Home Depot type stores at the end of the season "because they're past their
sell by date" !!! Only down side to growing indoors now is how thirsty the plants are