I've been growing potatoes for many years and plant the usual way; I plant them in a row, below ground level, and hill two or three times during the growing season.
The other night we were watching a BBC series called "Foyle's War", which takes place in England during WWII. In one scene, they were on a farm where people were planting potatoes. They had plowed the field with a newly acquired tractor into long, parallel ridges, about 2 feet high and 3 feet apart, and were planting the seed potatoes along the tops of the ridges. I guess the plan was that the plants would put down roots into the ridges and produce tubers down there.
Would that really work or was this just poetic license of life on the farm? I'd always heard that potato plants don't put out tubers below the level of the original seed potatoe, hence the hilling to build the ridges around the plants.
Paul