Onions compete as one of the most versatile vegetables on earth, and are found in basically every cuisine. Growing onions and choosing the correct varieties is an art. Harvesting and storing onions also has its own challenges.
Several members of our Inyo-Mono Master Food Preservers recently planted and harvested a plot of onions. The onions had reached a large size and looked quite nice, so we just pulled them up…. THEN we read about how to harvest onions correctly!
You may harvest and eat onions at any phase of growth. However, they will be larger if left until they have finished growing, and they will store better. Generally it takes approximately 100 to 120 days for onions to reach maturity in our area.
Pull up any onions that send up flower stalks as they have stopped growing and will not store well. Use these onions in 3-4 days. You do not need to cure them.
Harvesting Onions
Harvesting onions is simple, but there is more to the process than yanking them out of the ground.
Stop watering and fertilizing onions 7-14 days before harvesting to allow the onions to mature. When onions begin to mature, the tops will fall over. When the tops are yellow and approximately 70-80 % have fallen over, your onions are ready to be harvested.
You may bend the others over to hasten maturation of the rest.
Pick a day that is dry and harvest early in the morning when temperatures are more mild. If harvested in wet conditions, they will not cure properly and may rot in storage. Picking the right day to harvest can determine how well your onions will keep. Loosen the soil carefully around the onion bulb, then gently pull out the onion. Gently shake the soil from around the bulb. Any slight bruise may encourage your onion to rot. If you accidentally cut an onion, it will cause the onion to rot prematurely, so use it quickly. Place the onion outside in the sun for 1-2 days until the roots dry, they should be like brittle wires. If you are in a sunny, dry climate, such as Bishop, your onions may dry in a few hours.
Now you are ready to cure them.
Curing and Storing Onions
Generally long-day onion varieties store longer than short day varieties. Whether you grow long day, intermediate or short-day varieties, depends on where you live and which are more likely to grow the best in your area. Inyo-Mono counties are in the middle of the intermediate day variety growing area, and we also are on the cusp of the short day variety area. Past experience in gardens has been very positive with intermediate types.
Separate the softer, smaller onions and the thick necked onions and use these first.
Let onions cure on dry ground, out of the sun, or in a protected place like your garage or barn for 2-3 weeks. Do not cover with plastic or canvas. If they must be covered (i.e. for a short rain storm, etc.), use a light cotton sheet. Don't crowd the onions, keep them from touching if possible. The drier the air, the less time needed for curing. When the onions are dry, clip roots and cut tops back to 1-2 inches unless you are braiding the tops. This allows you to better see which onions should be used first and helps prevent them from rotting. When the onions look like the ones in the market, with dry, papery, thin, skins, you may store them. The ideal temperature is 40-60F.
To store them you may either braid the tops together, wrap them individually in newspaper, or hang them in a mesh bag or old nylon stockings. You may also put them in up to 2 layers in a cool, dark, well ventilated area.
Do not refrigerate your onions. Check periodically for sprouting or rotting onions, and remove them immediately. Rotten onions can be incredibly stinky!
Do not store onions with apples, pears or potatoes, as they may pick up the onion flavor. Pungent onions—those that make you cry the most—store longer, so use your sweet onion varieties first.
For More Information
Local Master Food Preserver website
Fresh Market Bulb Onion Production in California
Preserving Onions and Garlic (Clemson University)