Depending on your climate and when you planted them, some onions are ready to harvest in August, and some won't be ready until nearly the frost. But learning when and how to harvest is only half the battle—maybe less than half. The real green thumb status is in storing them. 

Learning to properly store onions provides a warm, cozy feeling, knowing you'll have homegrown onions to use all winter in loads of tasty and savory recipes. Do it wrong, and you'll be buying boring onions from the store every week. Plus, you'll have a slimy mess. As a bonus, since you may eventually run out of onions you grew, these storage tips and methods will extend the life of your store-bought onions, too.

How to Harvest Onions

Planting is fun, and watching the crops grow all summer—once the weeds are under control—is great, but it's harvest time that really gets my garden motor running. The hard work is paid off with tangible rewards. A pantry and freezer full of properly stored produce you grew is like looking at a large woodpile before a winter storm. It's a feeling of satisfaction and security. Okay, okay. Let's harvest some onions!

When are onions ready to harvest?

While there are many types of onions, we're talking about the standard bulbing onions here, like the traditional red or yellow onions you'd buy at the grocery store. These onions are ready to harvest once they've stopped growing larger bulbs. 

For most varieties, the green tops will start to yellow and flop over. That's when you are getting close. At this time, an onion or two can be pulled for immediate use and taken straight into the kitchen. However, for the big harvest, wait until the tops are browning. Browned tops that are starting to dry out are the sign it’s time to pull the onions. For many folks, that can be as early as late July, stretching on into September.

Do I harvest all onions the same way?

All bulbing onions are harvested in the same way. Red, yellow, white, or sweet, they all stop growing, flop over, and begin to dry. The time of year they're ready can be different based on their days to maturity and when they were planted. While some onions are famous for storing better than others, the procedure is the same. Of course, bunching onions, scallions, and green onions are harvested differently. 

Getting onions out of the ground

Once you've decided the onions are starting to look ready, watch the weather. Ideally, you’re looking for a few days without rain to help the soil and the onions to dry. If your soil is a bit more compacted, take a fork and loosen the soil near the onions (no need to pry them out, just wiggle things a bit) to help with drainage and drying.

On harvest day, you should be able to lift the onions right out of the ground by their stems. If they need a little coaxing with a hand trowel, that's okay, but take care to avoid damaging the bulbs. Bruised or cut onions don't store long. Brush off the soil—keep that valuable stuff in the garden—and take the onions somewhere you can lay them out for curing.

Storing Onions

While not all onions store equally, proper handling, curing, and storage conditions will help you get the maximum amount of time out of your crop. Some varieties, like the Patterson Hybrid, can be stored for a year!

Curing Onions

The onions you purchase have already been cured before you buy them. When you dig your own onions, you'll want to cure them for the best and longest storage. It's pretty easy. Really, we're just letting them dry out a bit.

• Brush off any excess soil that may be hanging on to the onions. Get rid of the clumps, but you don't need to get them squeaky clean. Don't wash them off. 
• Lay the onions one layer thick, not touching each other, either on the ground or on the floor of a shed, depending on the weather. As long as they're in a shady spot out of the rain, they'll be fine. After a week or two, they should be dry to the touch, and the outer skin should be crisp. Watch the weather, and don't allow the onions to freeze. 
• After they've cured, they're ready to braid if that's your plan. Otherwise, snip off the tops about an inch above the bulb. Set aside any onions with extra thick, still green tops to use first, as they won't keep as well. Toss any onions with even a small amount of mushiness. If you find bruised or damaged onions, set them aside for immediate use—they won't keep.

Damaged onions or those needing to be used immediately can be peeled, chopped or sliced, and frozen if there are more than you can use in a few days.

Onion Storage Conditions

Onions are not like ogres—they don't want to live in the swamp. When storing onions, pay attention to three factors: light, humidity, and temperature. 

Onion varieties bred for long storage can be kept in good condition for months, often right over the winter. Don't store them near apples or pears, which give off ethylene gas and will cause the onions to over ripen, just like other produce. Also, keep them away from potatoes. 

Light

Store onions in a dark place. The darker, the better, like in the cellar or the back of a closet. While onions will eventually get antsy and sprout no matter what, just like potatoes, they can be kept much longer in the dark. Storing onions in sunlight is a sure way to make them think spring is here and to start growing.

Humidity

Too much humidity can either encourage rot or sprouting. We want our onions nice and dry to the touch. The key to keeping humidity levels acceptable for storing onions is ventilation. Onions stored in a plastic bag or other impermeable container will likely rot, sometimes in as little as a couple of weeks. 

Choose a dry place and store them so air can flow around the onions. A mesh bag works well. Onions stored in a box or bin should be stacked only two layers deep with the lid left off. If you braid your onion stems and hang them in a dark, dry place, you have it almost perfect already. Keep onions at least a foot from the wall to ensure air can circulate around them.

Temperature

In my opinion, the temperature at which onions are stored is a little less important than keeping them dry and dark. If you have a cellar or basement that isn't damp, it's likely pretty good for onion storage. However, depending on your setup, a garage, shed, or even the back of a closet can work. The perfect temperature to store onions is about 45–55℉, but anything above 40℉ and below 70℉ works. Don't store them in the refrigerator. It's too cold and too damp. 

Inspect your stored onions weekly

Even perfectly stored onions can have a problem; one rotten onion can spread to the entire batch. Whenever you snag an onion from storage, or at least weekly, take 30 seconds to visually check how they're doing. Look for any signs of a rotten onion, including leaking onion juice, anything mushy or off-colored, and insects. Remove the problem onions and either use the good parts or compost the entire thing. 

Onions want to sprout, and when they do, it will make the rest of the onion soft and more prone to issues. Once they've started to sprout, their storage is pretty much over. A tiny green sprout in late winter is normal, but as it grows, it consumes energy from the bulb—that's why the onion plant made it. Early sprouting onions can be pulled from storage, chopped up and frozen, or used to make a pot of simply superb late winter homemade French onion soup. It's a great way to use up onions that are getting long in the tooth.