It will take 12 to 18 weeks to produce a crop depending on how frequently you fertilize and irrigate. Buy plants for setting anytime from September through March. This method is used primarily by gardeners for winter and spring onions for home consumption. Two to 3 weeks before harvest approximately two inches of soil should be worked around the base of the stem. This is known as blanching and results in onions that have a longer 'white and tender' stem.
Herbicides are available for excellent weed control.
Harvesting - Harvesting usually begins in late fall and continues to late spring. When the white bulbs are one-half to one inch in diameter the onions can be harvested. Undercut with a blade prior to harvest to make harvesting easier. Pull off the discolored outside skin leaving the basal part of the plant white and clean. Growers should check with their markets to determine the size of green onions their particular market prefers.