Preserving Onions and Garlic

Onions and garlic are relatives; both are in the genus Allium. Both are root vegetables whose bulbs grow underground. Both garlic and onion are very low in saturated fat, cholesterol and sodium. Garlic is a good source of calcium, phosphorus and selenium, and a very good source of vitamin C, vitamin B6 and manganese. Onion is a good source of dietary fiber, vitamin B6, folate, potassium and manganese, and a very good source of vitamin C. 

Drying Whole Onions or Garlic: Harvested bulbs typically are air dried before storage. Mature onions are dried in the field for several hours before being tied together and hung. Large garlic bulbs can be tied by the roots in bunches and hung on a string. Garlic or onions should be hung in a dark, warm room (70-75°F) with good air circulation. Bulbs should dry evenly without spoiling within two to three weeks. Completely dry garlic or onions should be stored in a dry, dark, cool (60-65°F), well-ventilated space in well-ventilated containers for 3 to 5 months. Drying is the best long term method for storing garlic and onions. For details of drying procedures, see DeLong (2006). 

Drying Chopped Onions or Garlic:

  • No blanching is required for either vegetable.
  • Wash onions and remove the outer "paper shells". Remove onion tops and root ends; slice ⅛ to ¼ inch thick. Dry onions in a dehydrator for 3 to 9 hours at 130°F to 140°F.
  • Peel and finely chop garlic cloves. Dry garlic in a dehydrator for 6 to 8 hours at 130°F to 140°F.

Canning Onions (but Not Garlic): Onions are low acid foods with a pH of 5.3 to 5.85. Thus, if they are to be canned, they must be pressure canned for safety. This tested recipe is specific for onions of 1-inch diameter or less. There is no scientifically tested process for canning garlic; disregard information to the contrary on the internet.

  • Wash and peel onions.
  • Cover with boiling water, bring to a boil and boil for 5 minutes.
  • Pack onions into hot jars, leaving 1-inch headspace.
  • Add ½ teaspoon salt to pints or 1 teaspoon to quarts, if desired.
  • Fill jar to within 1 inch from top with boiling water.
  • Remove air bubbles leaving 1-inch headspace. Wipe jar rims and adjust lids to fingertip tight.
  • Process pints or quarts in a pressure canner for 40 minutes. At altitudes of 0 to 2,000 feet, process jars at 11 pounds pressure in a dial gauge canner; in a weighted gauge canner, process jars at 10 pounds pressure at altitudes of 0 to 1,000 feet and at 15 pounds pressure for altitudes above 1,000 feet.

Freezing Onions: Bulb onions store well in a cool, dry place. Freezing is usually not recommended for onions or garlic. Garlic tends to get strong and bitter during freezing. The texture of both onions and garlic after freezing becomes mushy.

  • Choose mature onions and clean as for eating.
  • Water blanch for 3 to 7 minutes or until center is heated.
  • Cool promptly, drain and package, leaving ½-inch headspace. Seal and freeze. These onions are suitable for cooking only. Young green onions may be chopped for salads and sandwiches and frozen without blanching, but they will not be crisp. They will be highly flavored but may be slightly tough. 

Garlic-in-Oil: Oils may be flavored with garlic but only if prepared for fresh use, refrigerated and used within two to three days. Discard garlic-flavored oils left at room temperature over two hours. Garlic must be washed well and dried completely before storing in oil. The very best sanitation and personal hygiene practices must be used. Oil flavored with garlic provides a low-acid, air-free environment that can support growth of Clostridium botulinum, the organism that causes botulism. There are no canning recommendations for garlic-in-oil. 


  1. Andress, E.A. and J.H. Harrison, eds. 2006. So Easy to Preserve. Cooperative Extension Service, University of Georgia, Athens.
  2. DeLong, D. 2006. How to dry foods. Penguin Group, New York.
  3. HGIC 3085. Drying Vegetables
  4. HGIC 3260. Preserving Root Vegetables (Beets – Carrots – Onions – Sweet Potatoes – White Potatoes).
  5. HGIC 3470. Flavored Vinegars
  6. US FDA/CFSAN - Approximate pH of Foods and Food Products.
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