Onions are one of my favorite vegetables to grow in my garden each year. Most seasons I plant between 300-500 and the majority of them go into storage so we can eat our own onions all winter long. Figuring out how to store garden onions can be tricky, but I’ve been doing it successfully for many years and I’m willing to tell all of my secrets 😉
As with many of the vegetables I grow, my goal is to never buy an onion from the farmers market or grocery store…ever! Most years I succeed and that’s all due to the fact that I’ve learned to grow, cure and store onions for long term eating.
You can, too!
In this article you’re going to learn how to know when it’s time to harvest and how to store garden onions for the winter so can join me in never having to buy an onion from the grocery store ever again!
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How to Grow Awesome Onions
Before you can even learn how to store garden onions you need to know some of the tricks of growing awesome onions!
Successfully selecting the right varieties for storage, how to start seeds at home or where to buy the best plants, the best time to plant onions and the two most important conditions they need to thrive are some of the topics you’ll need to understand.
I’ve written the ultimate guide to growing onions and it’s always one of the most popular articles on my website.
How to Know When to Harvest Homegrown Onions
If you planted your onions in early spring, around the beginning of July you should start to look more closely at your onion plants. Find where they’re coming out of the soil and you’ll notice the bulbs starting to form.
Yay! They’re doing what they’re meant to do.
Technically you can start harvesting the onions whenever you want after they’ve started forming bulbs. If I’ve run out of storage onions by late June or early July I’ve been known to run out to the garden and grab an onion that was still growing to use for a recipe.
But, ideally you’re going to wait until the onions have completely stopped growing. And how do you know that?
The tops of the onions start to flop over.
This is their sign to you that they’ve reached their mature size and will no longer grow. The top green part of the plant bends over at the “neck” (the part between the bulb and the leaves) and essentially starts to seal off the bulb from the rest of the plant so it can start to dry.
You’ll notice that the flopping over happens gradually. Each onion will bend at the neck in its own time. I usually wait until all of the onion tops in a garden bed fall over before harvesting.
Within a week or so of all of the onions bending over you’ll want to harvest them. Don’t leave the onions in the garden for weeks on end baking in the sun and getting rained on. You want to start the curing process soon after they’ve reached a mature size.
How to Harvest Onions
Onions are pretty shallow rooted, so usually you can just pull them out by hand. They’re delicate and bruise easily, which will compromise their storage life, so be careful while harvesting and transporting them.
Brush off as much soil as possible from the roots (I always try to leave as much soil in the garden beds as I can.) and gently pile them in a wheelbarrow, basket or crate.
Every year I grow several varieties of onions. I have several long time favorites I can’t live without and I’m always testing out one or two new varieties.
For this reason I keep my onion varieties separate when harvesting and curing. I harvest one variety at a time, put it in its own crate, transport it to the curing area (aka, my garage!) and make sure to label it clearly. I keep everything in separate crates in storage as well so I can evaluate how well each individual variety lasts in storage.
If you’re a variety geek like me you can do the same thing.
How to Cure Freshly Harvested Onions
Curing your onions properly will help them last much longer in storage. If you take a look at a fresh onion when you pick it from the garden you’ll notice that it doesn’t have that dry, papery layer that onions from the grocery store have.
By curing the onion you’re helping that outer layer dry out and protect the onion and help it last longer in storage over the fall and winter.
And even if you’ve only grown a small amount of onions it’s still a great idea to cure them because it will help them keep for more weeks in your kitchen pantry.
One of the great garden hacks I’ve come up with over time is to use the metal rack from my DIY grow lights for seed starting and repurpose it to cure my onions. After seed starting season is over in May, I take down the lights and carry the metal rack into my garage.
There it sits and collects junk for two months until onion harvesting season begins. That’s when I have to clean it off and find a place for all that junk!
If you don’t have a metal rack you can use anything that allows for some air circulation around the onions to facilitate the curing process. I’ve used screens set up on sawhorses and plastic crates in the past.
You’ll also want to cure the onions somewhere out of the direct sunlight that is protected from the rain. I use my garage, but you could use a shed, covered porch, or other area. Just make sure there’s some air flow happening.
Now that you have your curing area ready to go, it’s time to bring the onions in.
You’re going to leave the onion leaves on during the curing process. Do not remove them yet.
I prefer to bend my onion over at the neck to seal off the bulb and then lay them out in layers on the metal rack. See above photo. I’ve seen other people lay them flat or even feed the leaves through the shelves so that the onions are hanging upside down.
Any of these methods work well. Choose a set up that’s easy for you to execute.
Remember to make sure to label the separate varieties you grew if you want to keep track of them.
After you have all of your onions set up on the curing racks you can leave them to cure for about 4-6 weeks. You want the onion tops completely dried out and the outer layer of the onion skin so dry that it looks like an onion you’d buy from the grocery store.
During the curing process you can feel free to use some of the onions! I’ll often make a trip out to the garage with a bowl and select some of the onions to bring inside for the week’s cooking. Fresh onions are so delicious!
How to Store Garden Onions
When the onion leaves are thoroughly dried out and brown and the outer layer of the bulb is dry as well, it’s time to learn how to store garden onions so they last as long as possible.
Your first step is to grab a pair of clippers (I use these or these) and cut off the roots and the tops. Leave about an inch of the neck attached to the bulb.
If you’ve only grown a handful of onions and you plan on keeping them all in your kitchen for immediate use, you can store them all in a big bowl. If possible keep the bowl in a cupboard or closet out of direct sunlight.
If you’ve grown enough onions for longer term storage then you’ll want to use crates, boxes or wire baskets for holding the onions. I use black plastic crates I purchased from a local garden center that stack easily and securely.
Onions store best (and longest!) in a dark, cool place at 35 to 40 degrees F. Basically the coldest place in your house that doesn’t freeze. I have a dark closet in my unfinished basement that I use as a quasi root cellar.
I carry all of the crates of onions into the basement storage area and stack them in a few rows. I stand back and admire my work and look forward to a year’s worth of onions!
How to Monitor Garden Onions in Storage
In ideal conditions onions can last up to a year in storage. But, they’re likely to sprout or sometimes rot before then. Check on your onions weekly to monitor for any issues. If you see some onions sprouting (pushing out green leaves from the neck) grab them and use them right away.
If you spot some rotting onions get rid of them immediately (into the compost they go!) to prevent the rapid spread to other onions.
A Note About Varieties for Storage
In my article about growing onions I explain the difference between storage varieties and fresh varieties of onions.
Fresh eating varieties tend to be sweeter and have more water content, but they don’t store well over the long term. You can expect them to store for about three months.
If you want to keep your onions for many months you should grow a storage variety. This is the majority of the onions I grow in my garden. Depending on how you prepare and store them you can expect them to last from 6-9 months or more.
Finding storage varieties can sometimes be a challenge when you don’t start your own seeds, but you may have luck finding storage variety plants at your local farmers market or nursery. I share favorite varieties and some options for ordering online in the growing onions article.
In my garden I usually grow one variety of sweet, non-storage onion (usually Ailsa Craig). I keep them separate and try to use them up before my other onions, ideally during the month or two following their harvest.
The rest of my onions are varieties bred for long term storage.
How to Preserve Onions From the Garden
I’m all about the easiest and quickest ways to preserve food. That’s why I love growing, curing and storing garden onions – it’s so straightforward.
If you have some onions that were damaged during harvest that you can’t eat right away or a lot of fresh eating varieties you’re afraid won’t keep, there are two ways I love to preserve onions besides storing.
These two methods also work well at the end of the winter when onions in storage tend to sprout.
Quick Pickled Onions
We’ve gotten into the habit of keeping a jar of quick pickled vegetables in our fridge most of the year to toss in our lunch wraps, on salads, and on top of egg dishes. This Quick Pickled Onion Recipe from Cookie and Kate is one of our favorites.
At the end of the winter I find that some of my onions start to sprout no matter how well I cured and stored them. I don’t like to see them go to waste, so I carve out some time in my schedule to sit down with a big pile of onions to prepare them for freezing.
Freezing onions is simple – just peel, chop and throw into freezer bags or containers. When you’re ready to use them just take a handful out of the freezer and throw it into a hot pan with some oil. Easy peasy!
I hope this article has taught you how to store garden onions and convinced you to try it this season. I promise, once you experience the sense of accomplishment that comes from growing and storing some of your own onions you might just get addicted and start planting as many as I do!
And if you grew garlic as well, the process of harvesting, curing and storing is very similar. And it also happens in July! Read all about drying garlic while you’re at it.
Additional Resources for Easy Food Preserving
FREE MINI-COURSE: Get Started Stocking Your Pantry for Winter. On a cold winter evening there’s nothing quite like using produce you put away yourself during the growing season.
This mini-course features 5 videos + worksheets to help you:
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