The best time to plant potatoes is right after the final spring frost. It is sometimes necessary to wait a few weeks just to be sure that a surprise freeze doesn't wipe out newly sprouted seedlings.
Potato sprouts do not withstand freezing temperatures very well. They thrive in moist, warm environments and require frequent watering, especially in a climate that has particularly arid summer months. These hardy crops do most of their growing during the warm summer months and require "hilling" every couple of weeks to keep dirt around the stalks of the plant. This prevents discoloration and a bitter taste to the resulting crop.