How to Harvest and Cure Your Onion Crop

Harvesting and curing 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).

Vigorously growing onion plants

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.

Onions ready for harvest

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.

Harvest onions on a dry, sunny day

One of the first stages of the onion curing process

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.

Final stage of the onion curing process

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.

Wiry roots and dry, papery skins indicate proper curing of onions

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.

Properly cured onions ready for storage

Properly cured onions ready for storage

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.

Onion with flower stalk through the bulb

Onion with flower stalk through the bulb

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.

Cured onions stored in mesh bags

Cured onions stored in brown paper bags

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!

Sets of onions that can be cured and replanted the following year

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July 12 2012      16 comments     Linda Ly
Jardín   Verduras

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  • Dalynn Holling

    This is my first time growing onions. I can’t tell you how many times I’ve googled “how to harvest and cure onions”. I am just so anxious to harvest and want to do it right! So on most of my onions, the bottom 2-3 leaves have yellowed and the tops have fallen over but a lot of them are still green. I’d say it’s probably been a little over a week. We’ve had a few warm, dry days and are supposed to have another one tomorrow. Should I go ahead and harvest or wait a few more days? Thanks for your detailed post!

    • http://www.gardenbetty.com/ Linda Ly

      If the tops have fallen over, they’re ready! The green leaves will dry up during curing.

  • ooohlaa

    Hi Betty … just discovered your posts in looking for fava bean info. I love your graphic pix and step by step thoroughness. Fabulous. My onions never balled up. When I pulled them out they were just long like scallions with very little area of actual onions so I used them as green onions, but of course those do not store well. This happened with both red and white onion sets, and both in ground and in pots. I am wondering what I did wrong? North Central FL Zone 8.5-9

    • http://www.gardenbetty.com/ Linda Ly

      In the southern part of the country, make sure you’re planting short-day onions, which will bulb with less daylight available. (Less meaning 10-12 hours a day.) They should go in the ground in fall and be left to grow through spring.

  • millpike

    Hi – Help!

    I always have a problem with drying out my onions and shallots and lose a lot of the crop to mould. My shallot stems had withered and they’d been in the sun, so I took them out of the ground just over 2 weeks ago and laid them in trays in single layers in a cool breezy shed (with a window in it), taking them out onto the lawn during dry weather. Today I took them out to remove the outer dried layer and found that under the dried outer layers many of them have a thick wet brown layer, like a thick wet blanket around them and some have already begun to go mouldy at the root end. This wasn’t visible if you looked at them, only when the outer dry layers were peeled away – last year I didn’t notice this and almost the whole crop rotted away.

    This also happens to my onions too and I’ve found the only way to resolve this is to strip off all the outer dried layers, leaving a ‘naked’ onion – it’s also time consuming and hard on the fingers and nails. Is the shed, which is cool, but gets some afternoon and evening sun, the right place to dry them? Do they need more sun/heat, or will that encourage the mould? Should I leave them in the conservatory (where it can get quite hot)?
    I’m going to lift my onions later this week and would love to know how to dry them well enough to store them.

    Have you any other suggestions??
    Many, many thanks
    Millpike

    • http://www.gardenbetty.com/ Linda Ly

      It sounds like your soil may be too moist when you harvest. Mine is super dry in the top 2-3 inches. Also, if you’re waiting until ALL of the stems have completely dried out before you harvest (and there is no green left), you’ve waited too long.

      For the next crop, you might also want to be more vigilant in watering only the soil around the bulbs, instead of watering overhead where water can collect in between the leaves.

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  • Polarrow

    Thanks for your post it is very informative.
    Well, I had all my onions drying in a nice breezy spot and this morning while I am getting ready to go bring them in, it had started to rain, it’s still raining. Will this effect them in a negative way?

    • http://www.gardenbetty.com/ Linda Ly

      They will need to fully dry out again before you store them. You can bring the onions into a garage or other indoor space to to finish curing them, as long as they have good air flow.

  • http://fourthgenerationfarmwife.com/ Becky

    Beautiful photos and wonderful post.  I love my onions.  Every year I think I need more they never make it much past fall.

    • http://www.gardenbetty.com/ Linda Ly

      Ditto! I would need to dedicate my entire yard to onions to keep up with how much I use all year!

  • Parsnip Love

    Wow, great post! We have yet to have an onion crop that hasn’t been stunted and slowly wiped out by thrip so we have never gotten to this step, but it is great to know how to cure them if we ever do. Thanks for posting!

    • http://www.gardenbetty.com/ Linda Ly

      Oy, good luck next year!

  • http://justawhimsicalworld.blogspot.com/ Kaitlin Jenkins

    This is great timing! My onions have all flopped and I wasn’t sure if I was supposed to be watering them still or not, thanks for the clarification! I adore onions, but this is my first year growing my own. So far they look great, and now thanks to you I know the next steps to take. Great post, thanks Linda!

    • http://www.gardenbetty.com/ Linda Ly

      Enjoy your soon-to-come harvest!

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