I harvested both our onions and garlic this week and am now drying them for storage. Onions are ready for harvesting when the tops have started to yellow and have fallen over. Garlic is ready to harvest once the leaves start to turn yellow.
Wait for a dry day about a week after the majority of the onion tops have fallen over to harvest. Harvest in the morning or on a cool dry day. Set them out to dry and remove as much of the soil as you can. I removed my tops later that day. Many websites tell you to leave the tops on for drying but I’ve also read that you can remove the tops to within an inch or two of the onion. I cut mine back leaving about two inches. Place the onions in a shallow container with good air circulation and dry in a cool, dry spot for about two weeks. Do not put the onions in direct sunlight to dry. The heat can destroy the onions and the sun can burn the outside layers. I left mine at the edge of the garage and open the door each morning. The onions do not receive any direct sunlight until late in the day but are exposed to air circulation. The process is basically the same for garlic.
Afterward, store in a cool, dry space in wood or mesh containers. Set aside any mushy or damaged onions for immediate use. I left my garlic in the garage in some used green mesh strawberry baskets last year and it lasted well into December (when we ran out!)