Provide your onions with about 1 inch of water per week. Soil should be moist but not soaked. Make sure soil is constantly moist after bulbs begin enlarging to produce a better yield of onions.
Stop watering your onions about a week before you harvest them. You can tell when the tops of the onions turn yellow or start to fall over. Cutting off water during this period will help the onions produce a protective layer of scales.
Harvest your onions when 3/4 of all the tops have fallen over by pulling the bulbs from out of the ground. Pull them out in the morning and allow the bulbs to air dry until late afternoon.
Hang the onions some place dry, such as a shed, tying the tops with string before hanging. Allow two to three weeks to dry out.
Cut the top 1 to 2 inches off the onions once dry, where the stem is bent over, with a knife.