While it’s true that you can harvest and use homegrown onions at any point, regardless of size, if you want to store your onion harvest so that you can still be enjoying your produce months from now, there are a few key steps you need to be aware of.
When to harvest
Firstly you need to be patient and let those onions grow to maturity. This means keeping them in the ground, with regular watering until the leaves start to show signs of withering and the stalks fall over, flat. This is your sign that the onions have finished growing. You can leave your onions in the ground now for a couple of weeks if you need some time before you can harvest but they won’t grow any more.
When you are harvesting your prized bulbs, try to resist the temptation to grab those stalks and pull the onions from the ground, however convenient that may seem. The secret to onions that can be stored long-term, is to make sure you don’t damage them at all. A bulb that is damaged, even bruised, is less likely to store well. So easy does it. The best method I’ve found for harvesting my onions is to use a garden fork to loosen the soil around and under the onion before pulling it gently and shaking the soil from it.
Once you have your onion out of the ground, you can gently lay it on the lawn or the ground nearby while you work on the others, again we’re trying to avoid dropping onions, bashing them against each other etc. so it’s easier to move them off to the side one by one as you harvest.
Don’t worry about there being dirt left on the bulbs, as we cure our onions for storage, this will dry and you can brush it off then, but if there are any mushy bits of leaves etc, you can peel these off at this stage. Any dirt that can be wiped off at this point can be but resist the urge to rinse your onions or to spend too much time trying to make them super pretty and clean.
So we’ve harvested, got them all ready and now is the time to begin curing them. Curing onions is the process of letting them dry out, letting the outside skins go papery and tight as all the moisture leaves the onion. This then allows them to be stored for the months ahead. If you are lucky enough to live somewhere warm and sunny with no forecast rain, you can start this process by leaving your onions out in the sunshine for a few days to help them dry off.
Unfortunately, it’s pretty wet and cold for us, so leaving my onions outdoors isn’t ideal, but that’s ok because you can leave them to dry in a garage or shed. We’ve fixed some strings along the roof of our garden shed and we have the onions hanging from there, leaves down and bulbs up.
There are gaps between all the onions to allow airflow between them, which again is perfect for getting them to dry.
It will take 3 or 4 weeks for the bulbs to dry, the outer skin to tighten and go papery, and the leaves to die off. Once this happens, we can cut the leaves off and store them somewhere cool and dark and hopefully, all gone well, you will have homegrown onions to use for many months to come.