Four days ago I added a pallet collar to each potato bed. Man, those plants are exploding from the ground!
The theory behind the raising of the beds is simple:
A potato plant will grow to a certain height. What grows from the "armpits" (where a leave sprouts from the main stem) depends on the armpit being above the soil or below it i. e. in the light or in lightless conditions. If no light is present a root will form. This is where the potatoes develop. If exposed to sunlight a leaf will form. By adding another collar I effectively shorten the plant. The plant will now grow back to the height it "wants". Below the soil the snipped off armpits will now develop into roots that should produce more potatoes.
This is how everything looked when I started.
Here's what I did:
I snipped off all the leaves from the main stem on the area of the plant that would be covered in dirt. Like so:
One of the beds is already growing hard and fast, so I'll probably be adding another collar within a week or so. The other bed is also growing, just not so fast. The plants were a bit smaller when I added the collar, so those will have a few weeks left to grow before adding the next collar.