When you look up most dinner recipes, chances are it’s going to call for onion. It’s a classic flavor that forms the foundation of dishes across regions and cultures.

So to be able to grow, harvest, cure, and store enough onions to last me a year of home cooking in the kitchen is something I’m quite proud of. Storing onions long-term in a way that actually lasts in the pantry helps me to get one step closer to my self-sufficiency goals.

In this guide, I’ll share the entire process, so you can maximize your own onion harvest in quantity and  quality.

Longer Storage Time Starts with the Variety You Plant

I have really good results with the long-day Blush onion - some are hanging in my kitchen right now in July from last year’s harvest, still perfect in quality.

Some onions aren’t known for their storage capabilities, namely sweet onion types. While you can still cure and keep them for a couple of months, they won’t last for 8-10 months like storage types.

Onion Harvest Preparation Tips

Stop Fertilizing: Onions are heavy feeders, so you’ve probably been giving them some organic fertilizer throughout the spring. My rule of thumb in my zone 7 garden is to stop feeding them on the 4th of July.

Remove Flowering Stalks: Keep a close eye on your onions - if they start growing a tall stalk with a bulb-shaped tip, pull that off and add it to a stir-fry for dinner. I made the mistake of not nipping all of those last year, and could tell that my onions suffered for it. They were thin, small, and kind of long and tough on the inside. Not ideal.

Stop Watering: Once you see that 2-3 leaves have died back, stop watering your onions. This will help them to get ready for the curing process.

Start Seeds or Plan Cover Crop: Starting some seeds ahead of time can help you to get another harvest out of your garden before frost. I have some ideas for what to grow after onions in this article.

When Onions Are Ready for Harvest

Onion leaves will tell you exactly when the plant is ready to harvest. The greens have totally died back and flopped over in the garden, you’re good to go.

If it’s possible, wait until you’ve had a stretch of no rain for a few days to help prevent your onions spoiling in storage later on.

Tip → Feed The Soil After Onion Harvest: Onions draw a lot of nitrogen up from the soil as they grow. Plan on nourishing your garden with a hearty application of composted chicken manure to replenish some of those nutrients.

Tools I like to use:

• Harvest Containers: Large box, basket or wheelbarrow: To transport your harvest without damage.
• Curing Location: Lay your onions out on racks so that they have good air circulation while they’re curing. You can also bundle your onions together with an elastic and hang them, or lay them out on a table in the shade.

How I Harvest Onions:

1. Pull bulbs upwards:
   • Gently lift the bulbs from the soil - pull upward from the  stem just above the soil surface.
2. Tap Off Excess Soil:
   • Shake off any loose soil on onions, but don’t worry too much about the dirt. It’s better to keep the dirt on,especially since you just peel the skin layer anyways.. I just tap them on the soil surface a few times or simply brush the dirt off.
3. Do not Rinse!
   • Keep your onions dirty! Washing can introduce moisture that may lead to rot during curing.

My Pre-Curing Preparation Plan

Cleaning:

• Lightly brush off any dirt with your hands. Don’t stress about it though
• Trim the roots slightly if they are excessively long or have dirt clods on them.
• Trim off the onion leaves so that around 6 inches remain if they are totally dry, or 12 inches if there is still a little moisture at the base of the stem.

Initial Sorting:

• Inspect each bulb for signs of disease or damage. Set aside any bulbs that aren’t perfect—they’re still great for fresh use in the kitchen!

Easy Curing Process

Onions are very easy to cure - the only three things you need to do are keep them dry, shaded, and well-ventilated. Once they’re set up, you don’t need to do much besides check up on them in a couple of weeks. Curing onions is like waiting for a fermented pickle recipe to get to that “just right” place - worth the wait!

• Use a metal rack or any kind of table
• Keep the trimmed stems in tact
• Lay the onions out on a single layer with some spacing in between each bulb
• Keep them dry. If weather is rainy and humid, it might be beneficial to run a fan on them for best results.

Environment:

• I have luck drying my onions out in a room in my house, where we keep the window open so a breeze is regularly blowing through. We don’t really control the humidity and do not heat or cool the room during  this time.
• UMass Amhert shares that temperatures in the range of 68-86°F and 70% relative humidity are ideal. In our dry summers, I don’t think I am able to achieve that high humidity in my curing area, thought.

Duration:

• Typically, curing takes 2-4 weeks. You’ll know it’s done when the outer skins are papery.

Chef’s Tip: You can still cook with newly harvested onions! Just peel off the outer couple of layers. I usually cook with my freshly harvested onions as its curing, and this helps me to see when they skin is fully cured and the onions are ready to go into storage.

Curing Onions Different Techniques

Field Drying in India

In India, dry weather means that onions can be cured easily in the field. According to a study from 2017, farmers simply “harvest the mature bulbs and lay them on their sides (in windrows) on the surface of the soil to dry for 1 or two weeks in hot tropical climates.” What’s interesting is that farmers will cover the onions with their leaves in order to prevent sun damage.

Gardeners who try this method will have longer storage time, according to the study, if you move the oniosn to a shaded place after a few days in the field.

How I Store Onions so they last for 1 year:

Proper storage is crucial for maintaining garlic’s quality and extending its usability.

Storage Conditions:

• A cool, dry place out of direct sunlight at room temperature works best.
• Don’t store onions with potatoes, as they tend to make each other go bad.

Storage Options:

• Mesh bags: Once onions are fully cured, we trim off the tops and any remaining root tendrils to store them in mesh bags. We put the bags on a metal rack so that they can get air circulation on the edges.
• You can also store your onions in any kind of box or basket. Just keep them above freezing.

According to PennState Extension, onions stored just over freezing at a 65% humidity level store well, but my storage area is not this cold!

A tip from UMass Amherst - don’t shock your onions by putting them right into 32 degree storage if that’s accessible to you. Instead, they recommend keeping onions in a place where they can acclimate to the naturally cooling temperatures of autumn will get you the best results. Otherwise, the onions are more likely to rot.

Conclusion

Properly harvesting, curing, and storing onion requires attention to detail, but the rewards are well worth the effort. By following these steps, you’ll enjoy a bountiful and flavorful onion harvest that lasts for months.

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