How to Harvest and Cure Onions

This past weekend, I pulled up 52 pounds of 10/15 onions.  Definitely my best onion harvest ever.  Now the question is, “What do I do with 52 lbs of onions”?  Since my wife and I are empty nesters, it is going to take us a while to eat all of those onions.  Especially when you take into account the fact that I just harvested an apple box full of shallots and I am still growing Egyptian Walking Onions.  I am sure we will be sharing with our kids and neighbors, but we are still going to have to preserve a large number of these onions.  Here’s how we preserve our onion crop:

10/15 onions in the potager two weeks ago

First, if you are new to gardening, you may wonder when to harvest or pull your onions.  The general rule is “Pull when the tops fall over”.  Below is a picture of what that looks like.  I believe in letting nature take its course.  I do not pull until 75% or more of the tops have fallen.  Once they fall, you can leave them in the ground for a week to ten days.  This starts the natural curing process.  However, do not leave them in the ground much more than ten days as that makes them susceptible to soil borne pathogens that can cause mold and rot in storage.  Just a little note,  I have heard several people say you have to cure onions before you can eat them.  This is not true.  Onions can be eaten at any time in their growth cycle (tops and all).  You only have to cure onions that you want to preserve.

The same onions from the first photo after their tops have fallen over

Once you have pulled your onions, spread them out in the sun.  Make sure they have room between them for air circulation.  I put mine on an old screen door up on saw horses.  The length of time varies.  If you pull them on a dry, hot day in Texas, then a few hours should be sufficient.  If it has rained recently, the onions moisture content will be higher and you will need to leave them out until the roots become noticeably harder than when they were harvested. 

Once they have completed this initial drying period, place them in a dry, shady place to allow them to complete the curing process.  Many people put them on their porch.  If you do not have room on your porch or in your garage, put them outside on a board or screen door to keep them off of the ground.  Place a sheet over them for shade.  Do not use plastic or canvas as this traps moisture.  You can cut the tops off at this time if you wish but if you do, leave about one inch of top on the onion.

Placing the onions on an old screen door. Allow plenty of space around them so they will cure properly.

While they are drying, turn them every few days to make sure they are drying evenly.  This part of the process can take two or three weeks.  You will know they are ready when the outer skins are papery and the roots are dry and brittle. 

Once your onion’s have cured, you can place them in mesh bags (or braid their tops together) and hang them in the garage for a little more drying.  If you are going to put them in a root cellar where humidity is high, you want to make sure they are as dry as possible.  Properly cured onions can keep for several months.  Check them often and discard any that are becoming soft.  If you see any sign of sprouting, eat them immediately, replant, or discard.

38 thoughts on “How to Harvest and Cure Onions

  1. hey jay! that’s quite a harvest you got there! i just harvested 16 ‘pinot rouge’ red onions yesterday, my first exciting crop of onions. i was amazed at how much smaller the bulbs were who’s tops i let flower… probably half to a quarter the size of the bulbs that didn’t go to flower. satisfying none the less. enjoy!

      • I live in KY & grow my slips from seed as it’s been historically impossible in my area to get the correct type of onion slip that will store for long periods. Go on line to Johnny’s selected seeds company in Winslow, Main or call 1877-564-6697 ( request a catalog)…They have a wealth of information about onions & you should select onions for storage based on your longitude / latitude. Also there are long day & short day onions. In my area I use the long day hard yellow storage varieties which will keep for over six months if cured & stored properly, I’ve tested several varieties & have settled on Expressions, Pontiac & Patterson. In that order of preference. Red Ring is also a nice red onion but will only keep for about 2 months. I’ve NEVER been able to get a white onion variety that will keep for longer than a few months. Some selected varieties are cold hardy & will over winter when planted in the fall. Mine were mulched in & survived a -7 last winter…I sowed my seed for next years crop on 7/23/15 in
        flats & will transplant the slips in about 6 weeks…Very easy to grow them… Hope this helps you some…Jim Goode, MS Horticulture Utica, KY…

        • Thanks for the great info Jim. I tend to agree that the whites have a shorter storage life. Where I live I have the best luck with with 1015Y’s and Yellow Granex. I also have good luck with my reds. Thanks so much for providing this info for any readers that live further north.

  2. i got them at the tamu holistic garden plant sale last fall as sets. bought one six pack that had multiple bulbils in each cell. i’ll definitely grow more onions in the future, they’re so easy and they don’t seem bothered by insects or neglect.

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  4. I have had great onions in the past, red, yellow and white. The past two years though my onions have been getting very mushy/soft some on the out sides some from the center. The ground is fairly airy so not sure why. Not sure if I’m leaving them in the ground too long. I leave them in until the tops actually start to turn brown. I do lay them out to dry on chicken wire suspended on saw horses out of the sun and under a tarp over head.

    • It is hard to say but you may be leaving them too long. I pull mine within two to three days after the tops fall. When onions are left in the soil they are exposed to several pathogens that actually live on, and are transported by, the organic matter in the soil. I would recommend in the future pulling and curing as soon as the tops fall.

    • You may be planting them too deep. I had my best crop of onion this year. I learned that when you plant the sets make sure that no more thsn half of the white part of the bulb is under the soil. The onion grows mostly above the ground, comes out clean an unaffected by moisture or bugs

  5. Thanks for the info, I grew mine from seed in the greenhouse using containers. Based on your pictures mine are ready to pull!

  6. Don’t worry about your excess onions – caramelise them (yummo!) and freeze in tart or serving size portions in zip-lock bags. Caramelised onion tarts will impress your family and friends. And you’ll love them!

    • Technically, onions are biennials. However, because we are so hot and our season is so long, many onions will flower in the first year. If they flower, you can collect and save the seeds. Once the heads flower, start watching them. After the petal die and start to fall off, you will find the seeds. the seeds are in clusters in a little “skin”. As soon as those skins open, you can collect them. If you do this, there is no need to dry them as nature has done that for you. Place your seeds in a paper container that breathes. Never store in a pill bottle or a ziplock bag as they trap moisture and can ruin the seeds. If possible store seeds in the refrigerator until ready to use. If properly stored they can be kept for two or three years but they are definately best if used soon.

  7. I can’t believe it! I pulled my onions and they are beautiful, left them out a few days to dry, weather was 80’s, left for a graduation and came home and it rained on them! Projected to be high 80’s to 90’s the next few days should I leave them in sun to dry, I hope I don’t lose them 🙁

    • They should be fine. If you want to make sure they are dry, move them onto a porch and let them dry a couple of more days.

  8. Our onions are HUGE! Forgot what kind we planted. They were planted as bulbs in April, now end of june (in Napa California), I have never seen such huge onions. I’m afraid to leave them until the tops fall over. Many are going to flower. I harvested the biggest ones this morning and curing them now. Is there a problem with harvesting too early? I put them in in the shade right away, we are having a heat wave for 4 days. Should I take them out and put them in the sun for a few hours tomorrow?

    • If they are beginning to flower I would definately pull them. Onions that flower do not store well. When they are as big as you want them, you can pull them at anytime. Congrats on a great harvest!

  9. Came across your How to Harvest and Cure Onions article and it’s been entirely helpful! And thanks for confirming that bending over the onion stalk is not going to help the bulb formation. I had been told that it was good to do that and it just didn’t seem to make sense to me.
    I’ve been gardening for decades but onions are fairly new for growing to me and I’ve had some limited success with the curing and storing so thanks for all the info, the pictures and the direct and well written information. Yes, I made mistakes with choosing the right onion for my geographic location here in Southern California. Took me a couple of years but I’m getting into my onion groove finally!
    I am going to be following your blog from now on. Cheers.

    • So glad you found the article useful and so glad you have become a subscriber. If you ever have any questions, feel free to contact us!

  10. I’ve been growing onions with varying degrees of success. I’ve lately started growing from seed that I saved from the previous year. A fairly good crop ensued this year. Now I need to move on to finding seed for varieties that are better suited for my latitude. The plan for next year is to construct a French Intensive bed and plant heavily – at least a couple hundred. I’ve been told that sweet onions don’t store as well as the pungent ones. Has that been your experience as well?

    • It has. However that doesn’t mean they won’t cure. They just won’t keep as long. Typically the more pungent onions keep four or five months for me. The sweeter onions have been good for two to three months

  11. Jay, thank you for your pictures and information. My daughter and I pulled our 52 red onions and she was so delighted every time she pulled one from the soil. It was like magic to her and so fun to do together. We grow a lot of onions here in Idaho, but it is wonderful to show your little one how it really happens. Thank you so much!!

    • Thank you so much for sharing that lovely story! My little ones have all grown to the age where they will soon be giving me grand children to take with me on the trips to my garden. How I have missed seeing the wonder and joy that the garden puts on a child’s face. Treasure these times and know that a garden is more than a great place to grow onions; it’s also a great place to grow kids!!!

  12. Thanks Jay for such an informative piece of literature, I found it very useful. However I have a question; I have grown 250 square metres of onions and I’ve just harvested them, is it advisable to spread them on the soil surface in the sun until the leaves dry off completely? Can I take them from there and straight into the packaging bags?

    • Dry them thoroughly before bagging. Here in Texas it is still 95f (35c). We can get by on about three days of curing. If it is cooler than that where you are located I would spread them out under cover and let them dry until the roots on the bottom of the bulb are very brittle. Also, the first layer of “skin” should become very thin and papery as well. Best of luck with your harvest. BTW, where are you from? When I see metres I assume your are not in the U.S.

  13. Pingback: Grow Bigger, Sweeter Onions | The Masters of Horticulture

  14. reading these posts has me confused they say to wait till tops fall over but another post says if they flower they don’t store as well.i have about 100 plants some of which have flowered and many others have the flower bulb on top but haven’t going to have to store a lot of these so what should I do.they are both red and yellow onions from sets

    • A good freeze on onions will cause them to set seeds. I am not sure where you are but I got two late freezes. Many of my onions have set seeds. I am pulling those and eating them first. Not all onion tops tumble. Right now I have harvested my Yellow Granex and Belle Reds. Only about 50% of the tops had fallen. However, since it has been such a weird year I pulled them and am curing them now. I have two more varieties that I will pull this weekend. I say pull the ones with seeds and eat them up first. Cure and store the others. Do not wait until ALL tops have fallen to harvest. If they have set seeds they are ready.

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    • Where are you located? We haven’t had onions in my part of south central Texas since the spring. To answer your question, you can harvest onions at any point of their development. So, feel free to pull them whenever you feel they are ready. If you want to dry and preserve them, I would stop watering them for a week or so before you harvest then dry them under cover for a couple of weeks.

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