How to harvest and store onions

The first time I grew onions was a total flop. I am such a fanatical feeder of my crops, the soil was just too rich and the bulbs never formed properly. Meanwhile, my good buddy Julie Ray from OG Harvest, a novice gardener at the time, completely ignored her onions and the bulbs grew beautifully… and she’s never let me live it down! So now I have learned the art of ‘backing off’ when it comes to fertilising onions, I just plant into a spot where the previous crop was heavily manured, and with little more than a regular drink, my onions form consistently plump and rounded bulbs, the way they’re supposed to.

When are onions ready to harvest? The general rule is to wait until the tops have died off and fallen over. They certainly won’t be growing any bigger after that! They tend to slow down as soon as the tops start to yellow. This is an important stage – you need to gradually reduce your watering to no water at all before lifting them out of the ground. Excess moisture spells trouble for mature onions - it can cause rot - so if you’re expecting a rain event close to harvest, get in and pull them out of the ground.

Be gentle. Any nick or bruise will create an entry point for rotting bacteria. Avoid serious cleaning at this stage. Just lift them carefully, tops and all, shake off a little excess soil and sit the plants in a warm, dry, shady spot for a few days to air dry. After this they are ready for the curing process.

How to cure onions. Trim off any slimy leaves and lightly rub off the soil, keeping as many outer scales intact as possible, and then place the bulbs in a single layer on an undercover table outdoors. Once two weeks have passed, clip the roots and cut back the tops to within 5cm of the bulb. Give them a wipe with a damp cloth and leave them there to dry for another 2 weeks. Now they are fully cured and ready for storage in a cool dry space such as a downstairs cupboard.

First published: November 2012

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