Let’s talk about harvesting those onions and the essential steps you need to take right afterwards!
You’ll probably notice that the greens of your onions will lay down on the ground at some point during their lifecycle. This is a strong sign that your plants are ready to harvest. If you want to get into the specifics, the very base of the growing tips will start to turn brown (as opposed to light green) and this signals the plant will grow no more and it’s ready to be harvested. There are no benefits to keeping them in the ground after this point.
To prepare your onions for long term storage, you need to perform what’s called a “cure.” This is basically where you lay out your onions on flat surface, in a single layer, and allow them to dry. The cure takes about 7 to 10 days, we usually let ours go for about two weeks. Try to disturb them as little as possible during the cure as freshly harvested onions are easily bruised and damaged. Once the cure happens, your onions are much more resilient to bumps and bruises.
There is little difference if you perform the cure with the greens still attached or not. We find they just get in the way, so we trim off the onion’s greens and also give the roots a bit of a trim. We lightly brush off any dirt that remains, but we don’t want to wash the onions. The microbes on the onion are essential for protection, so don’t wash the onions until you actually go to use them.
You can cure your onions either indoors or outdoors, so long as temperatures are above freezing. We often do ours outdoors under cover, but we’re using our ideal space for other things this year. If you’re doing it outdoors, just make sure they are in a dry location.
For long term storage, onions will keep at regular room temperatures. If you have a slightly cooler space, that’s ideal but no refrigeration or root cellar temperatures are necessary. It’s best to keep them in an “airy” container, you want plenty of air circulation. We use hanging mesh bags designed for fruit and vegetable storage, but re-used pantyhose will work just as well.
Onions will keep for about six months in the above conditions. We will often perform a blanch and freeze of our remaining harvest around the holidays. This ensures we have long enough storage to get all the way through to our next onion harvest.