Pruning, curing and storing onions from your garden – East Idaho News

Ron Patterson, East

Onions are an important part of the diet and are very easy to grow and store. As we approach the end of our growing season, I want to discuss when you want to harvest and treat and store onion bulbs.


It tells us when onions are ready for harvest – the neck is weakened and the leaves are pointed. This indicates that the onion has begun to grow. Necks may be forced, but this does not necessarily stop the growth, making them difficult to heal properly. Different species grow at different times. When collecting large onion slices, about half of the thumb rule is naturally pointed and the rest are close to maturity.

Harvest when plants and weather dry. Do not water for a week before harvest.

When the ends point, it is best to use a garden fork to loosen the soil under the bulbs, then gently lift – avoid pulling the ends or damaging the bulbs. That is easy.

Ron Patterson, East


The purpose of onion healing is to reduce the risk of damage and to prepare onions for long-term storage. Dry, outer scales seal around the bulb.

Commercial farmers cut and slice the onions, then take them to a controlled atmosphere to dry quickly and reduce the temperature. Home gardeners may need a little creativity.

After the bulbs are turned on, it is a good idea to get them out of the sun and into a shed or garage for good ventilation, so the outer scales should be dry and the necks should be sealed. Curing temperature is best between 70 – 85⁰F. Relative humidity should be around 70%, usually not a problem in East Idaho.

Onions can take 2-4 weeks to heal. You will be saved when you slide your neck. Wipe your neck between your thumb and forefinger. You can tell if it is slippery or dry. This reduces the chance of disease-causing organisms entering the bulb through the neck.

When not slipping, cut the dried leaves an inch or two above the natural fold. During the healing process, onions lose about 8% of their weight.

Ron Patterson, East


Do not remove the onion skin until you are ready to use it. The length of storage depends largely on the garden. Most ripe onions last up to nine months. Spanish yellow and walnuts usually last only 4-6 weeks. Onions should be kept in a breathable container – mesh bag, nylon stock, wicker basket. They thrive better when the temperature is between 32 – 35⁰F and humidity is around 70%. Onions stored at more than 40⁰F break the fast.

It is important to gradually lower the temperature over the next few weeks. Inspect the bulbs before inserting them into the storage area and use any damaged or loose parts as soon as possible, which will allow germs to enter the bulb. Of course, you can always cut and dry it or refrigerate the onion.

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