You’ll know that your onions are ready to harvest when the foliage starts to turn yellow and the bulb looks like it is almost pushing itself out of the soil. You can speed up the ripening of the bulb by easing the bulbs out of the soil a little and folding down the leaves to allow more sunlight to reach the bulbs. As the skin on the bulbs ripen, the leaves should wither.
After a week left in sunny weather, carefully pull the bulbs from the soil by hand or with a hand fork if needed and lay them on their sides for a few days to dry out the soil on the base of the bulbs. Onions bruise easily so wait until the soil is dry before you try to remove it. If the weather is too wet, don’t leave them sitting on the soil but bring them under cover or inside to dry out.
Onions can be stored in various ways: some people like to plait them into some string and hang them up; you can store them in a hessian bag or keep them in a crate which isn’t sealed or even hang them up in a pair of old tights. What matters most is that you keep your onions in a cool, dry place so they don’t rot and they will store well for months.