Granex-type varieties will produce green onions in 75 to 120 days, depending on the weather. Since spring day-lengths never get that long when onions are normally grown, these onions don't bulb. Some of these varieties have a bunching habit. These require 60 to 90 days for production. Shred litter from the previous crop and deep-turn the soil well before you plant.
Green onions grow best on beds formed with a rototiller or similar bed shaper.
Beds should be at least six inches high. Incorporate preplant fertilizer as you form the beds. Green onions don't require as much fertilizer as dry onions. However, they're still heavy users of some nutrients. Base all fertilizer and lime applications on a good soil test.