How to Cure Onions for Long-Term Storage

Onion curing is a method of preparing onions for long-term storage after harvesting. The curing process allows the onion plant to enter dormancy and lets the outer layer of the bulb dry out and form the papery skins you’ve probably seen at the grocery store.

The neck of the onion also tightens during curing, creating a natural seal to keep out harmful pathogens that could shorten its storage life and make it rot.

Curing onions typically takes two to four weeks, depending on air circulation, temperature, the relative humidity level, and the varieties of onions you’re curing. Onions will cure faster in a warmer, drier environment with more airflow.

Curing should ideally begin directly after harvesting onions from your plot or vegetable garden. Simply follow these steps:

1. 1. Remove dirt and withered leaves. Newly harvested onions are very sensitive, so it’s essential to eliminate any dirt from the roots carefully. Remove shriveled leaves with a pair of scissors or garden shears.
2. 2. Dry out the roots. The plant’s roots take one to two days to dry out completely. If the weather is warm and there’s a consistent breeze, leave the onions outside to dry in a single layer away from direct sunlight. If it’s wet or particularly humid in your area, bring the onions inside or leave them on a covered porch.
3. 3. Provide good air circulation. Keep the onions in a warm, dry place with good air circulation where they won’t get knocked around as their outer skins dry out. Suspend them in a basket to allow air to reach all sides of the onions, or lay them out in a single layer, periodically rotating the bulbs to allow even drying.
4. 4. Monitor the process. When the green tops have dried out completely and the necks of the onion bulbs have tightened and closed up, the onions have cured completely.
5. 5. Trim and inspect. Once the curing is complete, cut off the onion tops and trim the roots if necessary. Examine the bulbs for signs of sprouting or damage—a sprout or bruise can shorten an onion’s shelf life. These onions are still usable, but you should eat them first since they will likely become inedible sooner than unbruised options.
6. 6. Store properly. Providing your cured onions with the right storage conditions will ensure they last as long as possible. Store onions in a dark, dry, cool place (such as a root cellar, if you have one) or hang them in mesh bags to help them maintain their freshness for months.

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