Onions, garlic and shallots can add a lot to the home gardening experience. Iowa State University Extension and Outreach horticulturists offer tips for harvesting, drying and storing these popular garden items. To have additional questions answered, contact the ISU Hortline at 515-294-3108 or firstname.lastname@example.org.
Onions should be harvested when most of the tops have fallen over and begun to dry. Carefully pull or dig the bulbs with the tops attached.
After harvesting, dry or cure the onions in a warm, dry, well-ventilated location, such as a shed or garage. Spread out the onions in a single layer on a clean, dry surface. Cure the onions for two to three weeks until the onion tops and necks are thoroughly dry and the outer bulb scales begin to rustle. After the onions are properly cured, cut off the tops about 1 inch above the bulbs. As the onions are topped, discard any that show signs of decay. Use the thick-necked bulbs as soon as possible, as they don’t store well. An alternate preparation method is to leave the onion tops untrimmed and braid the dry foliage together.
Place the cured onions in a mesh bag, old nylon stocking, wire basket or crate. It’s important that the storage container allows air to circulate through the onions. Store the onions in a cool, moderately dry location. Storage temperatures should be 32 to 40 degrees Fahrenheit. The relative humidity should be 65 to 70 percent. Possible storage locations include a basement, cellar or garage. Hang the braided onions from a rafter or ceiling. If storing the onions in an unheated garage, move the onions to an alternate storage site before temperatures drop below 32 F.
The storage life of onions is determined by the cultivar and storage conditions. When properly stored, good keepers, such as ‘Copra’ and ‘Stuttgarter,’ can be successfully stored for several months. Poor keepers, such as ‘Walla Walla’ and ‘Sweet Spanish,’ can be stored only for a few weeks.
Harvest garlic when the foliage begins to dry. In Iowa, garlic is usually harvested in August or September. Carefully dig the bulbs with a garden fork or shovel.
Dry garlic in a warm, dry, well-ventilated location. Place the garlic on an elevated wire screen or slotted tray to promote drying.
When the tops have dried, cut off the dry foliage 1 inch above the bulbs. Also, trim off the roots and brush off any loose soil. Place the bulbs in a mesh bag or open crate and store in a cool (32 to 40 F), dry (65 to 70 percent relative humidity) area. Garlic can be stored for three to six months if properly dried and stored. An alternate way to store garlic is to braid the foliage together immediately after harvest, dry and then hang the braided garlic in a cool, dry location.
Harvest mature bulbs in late summer when the tops have turned yellow and begun to dry. Cure the shallots in a warm, dry location for one to two weeks. After the shallots have been cured, cut off the dry foliage, place the bulbs in a mesh bag and store the shallots in a cool (32 to 40 F), dry (60 to 70 percent relative humidity) location. When properly cured and stored, shallots can be successfully stored for six months or longer.