How to harvest onions?

How to Harvest and Cure Your Onion Crop

Here we are, a whole season after the first onion seeds were sown, and those little specks have slowly grown into a bed of bulging, fragrant alliums.

While onions can be harvested and eaten at any stage, the most satisfying part of growing onions is being able to pluck a fresh onion from the pantry months after you’ve plucked it from the ground. Curing makes that happen.

Curing is a month-long process of drying down your onions to prep them for storage. Once properly cured, onions store for a very long time — through the fall and winter, and sometimes even spring under the right conditions. (Though I’ve never actually had an onion store through the spring, since my harvest is long gone by March. What can I say, I love onions.)

When your onions are vigorously growing through the longer days of spring and summer, their stems are lush and happy and green. You might even have a few onion blossoms topping those stems (more on those later).

When they’ve finished developing, you’ll notice the lowest leaves start to yellow and wither. Shortly after, the stems will flop over at the neck, as if all your plants had just died. The onions won’t look very appetizing either. Fear not. Wait for most of your crop to flop, then bend over the stems of any remaining upright plants. You can simply bend them above the bulb; this will signal the plants to enter dormancy.

If some of your onions have sent up flower stalks, you can just leave them be. The leaves around the stalk will still wither naturally when the onion is ready for harvest, so you don’t have to bend over the stalk. I don’t recommend cutting it off, because it could introduce bacteria into the onion during the curing process.

At this point, stop watering and leave the onions in the ground for 7 to 14 days (depending on how dry or humid your climate is) to allow them to fully mature.

On a dry, sunny day, carefully pull each onion out by the bulb, or by digging around it. Grasping the weakened stem could cause it to pull off entirely, and you want the stem intact to reduce the likelihood of rot. Lay the onions out on the ground, or in another open, sunny area, for a day or two to dry out the roots.

But wait! You’re not done yet. After a nice day of getting their tan on, move the onions into a breezy, shady spot (such as a covered porch, or under a tree) and lay them out one by one. You don’t need to clean off the onions yet. Just set them out to dry, dirt and all, until the stems turn brown and brittle. This rest period allows the onions to go deeper into dormancy so that they’re less susceptible to disease.

If you have absolutely no shade around your house, you can lay them in the sun but covered with a thin cotton sheet (never plastic or canvas, which could stifle them) to prevent sunburn. If you tend to get rain in the summer, you can cure your onions in a garage or basement, but turn them over a couple times a week to ensure even drying. The important part of curing is having plenty of air circulation around the bulbs. Because of this, it’s best to lay them out without crowding them, rather than heaping all your onions into a basket.

This last step of the curing process takes two to three weeks. You want your onions dry, dry, dry. The roots will become wiry and the papery outer skins will tighten around the bulbs.

Now you can clean ’em up by trimming off the roots and stems with shears. A couple layers of the outside skin will usually flake off with the stems, leaving you with a smooth, spotless onion.

If you had a few onions with flower stalks growing through the bulbs, use those up first. The stalks retain a lot of moisture (even after curing) and will cause the onions to decay sooner in storage. They’re perfectly fine to eat and usually keep for a month or two.

For the rest of your onions, stash them in a cool and dry, dark and airy space, inside brown paper bags, mesh bags, milk crates, wire or wooden racks, or any well-ventilated storage shelf. Sweet, juicy onions (including many short-day onions) tend to not store as well as firmer, long-day varieties, so you’ll want to use them first.

Keep in mind that even after curing, onions are still very much alive and need cool, dry conditions to stay dormant. Any change in temperature or humidity can cause them to break dormancy and sprout again. You should check your onions every few weeks for green shoots that might emerge in storage. (I once let them linger in a warm room for a couple of months, and came back to alien-like tentacles taking over my shelf. The onions were still good to eat, though.)

If you happen to have some teeny tiny onions (I usually get a few that never got around to growing, but are too small to be used like shallots), cure them and save them for next year — you’ve just grown your very own “set” of onions! Replant them in the spring, where they’ll mature into full-sized bulbs in less time… and you’ll have a new harvest even sooner!

Onion Harvest Time: Learn How And When To Harvest Onions

The use of onions for food goes back over 4,000 years. Onions are popular cool season vegetables that can be cultivated from seed, sets or transplants. Onions are an easy-to-grow and manage crop, that when properly harvested, can provide a kitchen staple through the fall and winter.

Success in Harvesting Onions

Your success in harvesting onions will depend on proper planting and care throughout the growing season. Plant onions as soon as the garden can be worked. Rich soil, consistent moisture and cool temperatures help bulb development. It’s best to create hills for onions that are to be used for green onions but do not hill those to be used for bulbs.

When to Harvest Onions

In addition to good planting, you need to know when to harvest onions for the best flavor. Harvest tops for green onions as soon as they reach 6 inches in height. The longer you wait to harvest the green tops, the stronger they become.

Any bulbs that have bolted, or formed flower stalks, should be pulled and used right away; they are not good for storage.

Bulb onion harvest time can begin with onion tops naturally fall over and brown. This is usually 100 to 120 days after planting, depending on the cultivar. Onion harvest time should be early in the morning when temperatures are not too hot.

How to Harvest Onions

Knowing how to harvest onions is also important, as you don’t want to damage the plants or onion bulbs. Carefully pull or dig onions up from the ground with the tops intact. Gently shake the soil from around the bulbs.

Drying and Storing Onion Bulbs

Once harvested, storing onion bulbs becomes necessary. Onions must first be dried before they can be stored. To dry onions, spread them out on a clean and dry surface in a well-ventilated location, such as a garage or a shed.

Onions should be cured for at least two to three weeks or until the tops necks are completely dry and the outer skin on the onion becomes slightly crisp. Cut tops off to within one inch after drying is complete.

Store dried onions in a wire basket, crate or nylon bag in a place where the temperature is between 32 to 40 F. (0-4 C.). Humidity levels should be between 65 and 70 percent for best results. If the location is too damp, rotting may occur. Most onions can keep for up to three months if dried and stored properly.

The first time I grew onions was a total flop. I am such a fanatical feeder of my crops, the soil was just too rich and the bulbs never formed properly. Meanwhile, my good buddy Julie Ray from OG Harvest, a novice gardener at the time, completely ignored her onions and the bulbs grew beautifully… and she’s never let me live it down! So now I have learned the art of ‘backing off’ when it comes to fertilising onions, I just plant into a spot where the previous crop was heavily manured, and with little more than a regular drink, my onions form consistently plump and rounded bulbs, the way they’re supposed to.

When are onions ready to harvest? The general rule is to wait until the tops have died off and fallen over. They certainly won’t be growing any bigger after that! They tend to slow down as soon as the tops start to yellow. This is an important stage – you need to gradually reduce your watering to no water at all before lifting them out of the ground. Excess moisture spells trouble for mature onions – it can cause rot – so if you’re expecting a rain event close to harvest, get in and pull them out of the ground.

Be gentle. Any nick or bruise will create an entry point for rotting bacteria. Avoid serious cleaning at this stage. Just lift them carefully, tops and all, shake off a little excess soil and sit the plants in a warm, dry, shady spot for a few days to air dry. After this they are ready for the curing process.

How to cure onions. Trim off any slimy leaves and lightly rub off the soil, keeping as many outer scales intact as possible, and then place the bulbs in a single layer on an undercover table outdoors. Once two weeks have passed, clip the roots and cut back the tops to within 5cm of the bulb. Give them a wipe with a damp cloth and leave them there to dry for another 2 weeks. Now they are fully cured and ready for storage in a cool dry space such as a downstairs cupboard.

First published: November 2012

Storing Onions – How To Store Homegrown Onions

Onions are easy to grow and produce a tidy little crop with very little effort. Once the onions are harvested, they keep a long time if you store them properly. Some methods of how to store onions will keep them for months. Storing garden onions properly rewards you with your own harvest in the middle of winter. Few things are better than using your own produce when snow covers the ground and nothing green and growing is possible.

Store Fresh Green Onions

Spring onions and green onions won’t store long. They can hold in the refrigerator crisper for a week or possibly more, but are best fresh. These onions are used for their stems as much as the ends. The stems must be kept green and crisp for the best taste. Store green onions that still have their roots in 1/4-inch of water in the refrigerator to keep the onions fresh longer. Change the water daily to prevent bacteria.

How to Keep Onions

You may wonder how to keep onions so they last well into the cold winter months. The bulbs are hardy and keep well if they are harvested at the right time and hardened off. The proper time to dig them up is when the sprouts have died back.

Then, onions need to be cured. Curing dries the outer skins of the bulb so it won’t be as prone to rot and mold. Spread the onions in a single layer on a clean, dry surface. Let them dry for two or three weeks until the necks are dry and the skin is papery. After they are cured, storing onions can be done in a couple of different ways.

Cut off the tops or necks of the onions after they are cured. Discard any that show signs of decay or have soft spots. Use any bulbs that have thick necks first because they are more moist and don’t store as well.

A fun way of storing onions is to put them in an old nylon stocking. Make knots between each bulb and hang the nylon. This keeps air circulation flowing and you can just cut a knot off as you need a vegetable.

Another method of storing garden onions is to set them in a basket or crate. Any container will do as long as there is airflow.

Best Conditions for Storing Garden Onions

All produce keeps best in cooler conditions, which slow down the decay process. Onions should be kept where temperatures are 32 to 40 F. (0-4 C.). An unheated basement or garage is suitable as long as temperatures don’t freeze inside. The location must also be dry and low in humidity to prevent rot and molds. The length of time you can store onions will depend on variety and site conditions. Some bulbs can be stored for several months.

Most onions respond well to organic gardening methods, so if you decide to try some in your garden, you may end up with a bigger yield than you expect. So once again, you may be out canvassing the neighborhood with free veggies at the end of the season. If that doesn’t appeal to you, try drying and storing them instead.

It doesn’t take all that much extra effort to ensure that you have plenty of fresh, homegrown Vidalias or another variety of onion available all through the winter. Just keep in mind that your onions need to be thoroughly dried before you make any attempt to store them at all, or they’re likely to rot. Stored onions are very susceptible to fungus-borne diseases.

Harvesting Onions to Dry

To start with, don’t harvest your onion crop until the tops of the onions begin to dry up and fall over on their own. At that point, carefully lift them out of the ground early on a sunny morning and leave them in the field until late afternoon, so they have time to air dry. Then remove the roots and clip the tops back to one inch.

How to Dry Onions

Once the tops have dried for several days, spread your onions out in a relatively cool, dry, and (above all) well-ventilated place out of direct sunlight. Let them dry for 2-3 weeks; you’ll be able to tell they’re dry enough when several layers of skin are crisp, papery, and of a uniform color. Be sure the neck doesn’t slide at all when you roll it between thumb and forefinger.

Storing Dried Onions

Now that your onions are dry, they should be stored somewhere where plenty of air can flow around each onion, keeping them dry at all times. Check your onions regularly; if you find a spoiled one, discard it immediately before it infects the others. Make sure onions are not stored in plastic bags, only mesh bags for airflow.

Want to learn more about drying onions for storage?

Don’t miss these helpful resources:
Preserving Onions and Garlic from Clemson University Cooperative Extension Service
Yellow Storage Onions from niversity of Minnesota Extension

March and April are what we call the cool season when it comes to veggies.

Typically that means it’s the season to plant vegetables either for their roots — such as onions, potatoes or carrots — or for their shoots (think leaves) — such as lettuce, cabbage and spinach, but also broccoli and cauliflower.

In this column, I’m focusing on just one of the many cool-season vegetables: the onion.

First, it is important to understand how an onion grows. It is what we call a biennial, which is a plant that grows vegetatively one season, then goes to seed and dies the second season.

So if you were to plant your onions from seed this year and left them in the ground over the winter, they would form a bulb the next summer and then go to seed and die. When an onion goes to seed it will rob energy from the bulb, and you end up with more or less a hollow bulb. More about that later.

Onions can be grown from seeds, transplants or sets. You can find all three available this time of year. Here are the differences.

Onions from sets: Sets come in mesh bags and look like miniature onions. These are essentially onions that were grown last year from seed and then harvested at the end of the season. When I plant sets, I space them only a few inches apart so I can eat green onions as I thin them. It only takes about four weeks from the time you plant a set to the time you can start eating green onions.

The remaining plants will continue to grow and eventually form a nice-sized bulb. If your onion plants send up a flower stalk, break it off immediately or else you won’t get a bulb. Harvest onions when the tops start to die back. Sets usually work great for onions that you want to store. Some varieties to look for are White Snowball, Yellow Stuttgarter, Red Karmen and Sweet (a generic sweet variety).

Onions from transplants: Transplants are also onions that were started late the previous year, but they are much younger and rarely go to seed as readily as sets. Like sets, I plant them close at the start but eventually allow 6 inches between them as they mature. Walla Walla, Red Wing and Yellow Candy (my new favorite onion) all come as transplants and are sweet varieties that are good for fresh eating but don’t store very well.

Onions from seeds: You can also buy packets of onion seeds, but it will take two years for them to form bulbs. That’s why I recommend that you plant onions from sets or transplants. However, if you just want green bunching onions, then seeds are the best way to go. Simply follow the directions on the seed packet for depth and spacing.

Onions are heavy feeders so be sure and incorporate plenty of compost and a good balanced organic fertilizer at the time of planting. Like all veggies, the richer the soil the bigger the harvest.

When your onions start to dry up break off any flower stalks, stop watering and let them harden off in the sun for a couple of weeks. After that you can clean them up and store them in a cool, dry place so you can enjoy homegrown onions for several months. It’s just that easy.

Steve Smith is owner of Sunnyside Nursery in Marysville and can be reached at [email protected]

Two free classes this weekend

A class on nativars at 10 a.m. April 1 is followed by a class on flowering trees at 11 a.m. April 2 at Sunnyside Nursery, 3915 Sunnyside Blvd., Marysville. For more information, visit

Yard and Garden: Harvest, Dry and Store Onions, Garlic and Shallots

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 [email protected]

How do I harvest, dry and store onions?

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.

How do I harvest, dry and store garlic?

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.

How do I harvest, dry, and store shallots?

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.

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