Are you confident that you know how and when to harvest onions and how to store them?
Growing your own food means learning more than just the basics of sowing, planting and plant care. Growing onions at home can be a great option, both for experienced and novice gardeners. But there are a number of things that it is possible to get wrong when it comes to the onion harvest, and when it comes to preparing and storing your crop.
To help everyone make sure that they make the most of their onion harvest, and prevent waste, here is a brief guide to the onion harvest and onion storage. Read on for information and advice for each stage of the process.
When to Harvest Onions
Precisely when to harvest onions will depend on which type and variety of onion you are growing. In this article we are focusing on bulb onions, rather than on those grown for their greens. But even within this category, there is still a lot of variety.
Those whose sets are planted in autumn for overwintering will typically be ready sooner than those whose sets are planted in spring. Typically, however, bulb onions are harvested from around midsummer or a little later in summer.
Precisely how and when to harvest onions can vary year on year, with different weather and environmental conditions, as well as with variety and type.
But it is important to time things correctly because those harvested too early at an immature stage don’t store as well as those harvested at the optimum time. And leave your onions too long and they could fall prey to a whole host of pest or disease problems.
Typically, you should gauge the perfect harvest time by observing your crop. Wait until at least a third of your onions have foliage which is beginning to turn yellow and flop over – dying back naturally – then you should know when to harvest onions.
Preparing to Harvest Onions
Now you know when to harvest onions, it’s time to get down to business!
A successful onion harvest begins a while before you actually take the onions out of the soil or growing medium for storage or use.
Here are a few tips to help you make sure you have good onions when you harvest onions:
- In around June, add a potassium rich liquid plant feed or organic mulch to help onion bulbs to ripen.
- Around midsummer, once the bulbs have swollen, stop watering and feeding your crop. Make sure you absolutely avoid the use of fertilizers (especially those high in nitrogen) during the last 6 weeks or so of growth.
- Wait for the foliage to die back naturally, yellow and flop over. Some gardeners bend over the foliage or lift the bulbs to break the roots. However, these strategies are no longer recommended.
One more important note to make is that a successful onion harvest will also depend on choices you have made earlier in your growing efforts. First of all, your success will depend on the right choice when it comes to which onion variety or varieties you grow.
If you would like to store onions for later use, it is important to note that some onion varieties will store better, and last much longer, than others.
How to Harvest Onions
Damaged onions will not last as long as those that are unblemished and fully intact. It is important to take care during the harvest to avoid damaging the bulbs.
To keep onion bulbs as intact and unblemished as possible, it is best to use a garden fork or another gardening tool to gently ease the onions from the soil, rather than trying to tug them up and out of the soil by hand.
Lay the harvested onions gently to one side – don’t toss them around. Check each one over as you harvest it, gently dusting off the worst of the dirt. Put any that are showing signs of damage, or any that are smaller or malformed to one side. You can put these in a pile to be used up more quickly.
How to Prepare Onions for Storage
Once you harvest onions, you can of course, if you wish, use them up in your kitchen right away. However, if you have grown more than a handful of onions, you will no doubt want to store at least some of your onions for longer.
To make sure that onions last in storage, the next stage of the process after harvesting is to leave onions to cure.
Curing is essential preparation for onion storage without freezing or drying. It simply means leaving onions in a warm, dry, well ventilated spot so that the moisture dries from the outer layers, forming a more effective barrier for the rest of the onion within. For best results, onions should be left to cure at between around 25 and 30 degrees C.
A well-ventilated polytunnel in summer can be a very good place to cure onions for storage. Spread out your onions in a single layer on mesh cooling trays or on a shelf in your polytunnel, or peg them to a line between crop bars, for example.
The onions should cure until the necks have tightened up, stems are free from moisture, and the outer skins feel and look all papery and taut. Only once these things have occurred should the onions be taken elsewhere for longer term storage.
Where to Store Onions
Once you’ve gauged when to harvest onions and gone through the process, you need to store them well.
Typical bulb onions will belong to one of two onion types. They will either be mild onions (which are usually poor for storage and which must be used up within a few weeks), or pungent onions, which can typically be stored, in optimal condition and in an ideal environment, for ten months, or even up to a year.
If you are not sure which variety or varieties you are growing, or are not sure whether your onions are pungent or not, cut into them. Onions that make you cry when you cut into them will last longer. The sulphurous compounds that make our eyes sting also inhibit rot.
So put your most pungent onions into a pile for longer term storage. And use milder onions up more quickly, or preserve them in other ways.
The best place to store onions is in a cold store/ pantry or old fashioned root cellar. But of course, not everyone has these spaces. A regular cellar, garage or shed can also work well.
To make sure that your onions last as long as possible in storage, aim for consistent temperatures between 4 and 10 degrees C.. Even in a somewhat warmer cool space, however, many onions can be stored successfully. For best results, relative humidity should be kept between 55% and 65%. And this humidity level can be more important than the temperature in preventing any issues when onions are stored.
The goal is to create a cool, dark environment, with a little ventilation but not too much. In such an environment, rot is less likely to set in, and the onions will not lose too much weight through respiration. A little ventilation is needed so that there is not an increase in CO2 levels, and to dissipate heat generated by the onions as they continue slowly to respire.
How to Store Onions
In addition to thinking about the general environment in which your onions should be stored, around the time you harvest onions it is also a good idea to think about storage solutions. There are a number of ways to effectively store your onions that can provide the right conditions and allow you to keep them for longer. Here are some examples of the options you could consider for onion storage:
In Braids Hanging from the Ceiling/ Hooks
Braiding onions is a traditional way to prepare them for storage. In addition to looking decorative, braiding them can also help keep them fresh. The braids can be hung from a ceiling or from hooks, and this means that they are sure to get a light amount of ventilation. Another advantage of creating braids is that you can also easily see all your onions. And to remove any that might be beginning to spoil as soon as you see signs of a problem.
Begin with three onions, lay them out together, then braid their stems – right to middle, left to middle, right to middle etc.. Then take the stem of a fourth onion and add it to the stem at the centre. Again, braid by taking the right to the middle, then the left to the middle. Continue to add onions to your braid in this way, making sure that you take up the new stems you add each time.
If this seems a little too difficult, or the stems are too short or breaking easily, there is another way to make strings of onions that is even easier. For this second option:
- Take a length of twine and make a loop by tying the ends together. (Make this long enough to accommodate the number of onions you want to have on each string.)
- Take an onion and wind the stem in a figure of eight pattern around the base of the string, between and around the two upright strands.
- Add your next onion, and make another figure of eight pattern, passing the stem between the two upright strings from front to back
- And then another onion, this time going first front to back before making the figure of eight pattern.
- Continue until you have added enough onions to your string.
The twine will help keep your strings of onions in tact. And you won’t need as much stem to keep each onion firmly secured.
In Mesh Bags/ Hose
Of course, braiding your onions after you harvest onions is traditional. But it is most definitely not your only option. You can also simply hang your onions in mesh bags. Another interesting variation of this idea is hang your onions in old tights. Take a leg and drop an onion into the base. Tie a knot, then add another one. Then continue to do this to safely store your onions.
You might also use storage vessels or store structures to store onions, such as cardboard boxes with holes, wicker containers, or orchard racks, for example.
One thing to mention, whichever option you choose, is that it is not a good idea to store onions in too close proximity to other stored crops. Storing onions near other crops, like potatoes and apples for example, can affect their taste.
Remember, if you don’t have suitable conditions to store onions traditionally, you can also freeze your onions, dry your onions, or use them in canning recipes.
Elizabeth Waddington is a writer and green living consultant living in Scotland. Permaculture and sustainability are at the heart of everything she does, from designing gardens and farms around the world, to inspiring and facilitating positive change for small companies and individuals.
She also works on her own property, where she grows fruit and vegetables, keeps chickens and is working on the eco-renovation of an old stone barn.
To get in touch, visit https://ewspconsultancy.com.