Why in the north potatoes instead of wheat

 At https://yle.fi/aihe/artikkeli/2016/01/28/talvi-yllatti-viljelijat-1968 there is an old video of first snow having come unusually early to Lappland, wheat left partly in the fields, usually falled down and ruined. But potatoes were under the snow in the not-yet-frozen ground, easy and nice to collect. I remember from my youth having taken part in such some year in southern Finland, in our garden in Helsinki. In the video it looked much the same in atmosphere, except more countryside like and more northern, without any atmospheres of cars and city streets.