Who plants potatoes in January? I do! This photo shows 10 plants, 2 of 5 varieties: All Blue, All Red, Colorado Rose, German Butterball, & Yukon Gold. In December we dug out this narrow bed and laid down gopher wire, which we shaped like a basket. The basket is about 16 inches deep. I back-filled a couple of inches of soil, then set out my seed potatoes. Next I covered them with 6 inches of soil/compost. (Please note that this is more than the recommended initial covering for potatoes...I can do that because my soil is SOOO sandy.) Now that they have really taken off, I add some compost every few weeks to continue filling in the bed.
As a side note, I just found a stow-away potato plant growing like gangbusters behind the greenhouse. It was a leftover from last summer. After an accidental crushing of the top growth, I decided to dig it up. Six cute little potatoes was my reward. Nice.