How do you can fresh onions?

Onions are a versatile vegetable that can be used to add flavor to many dishes. When fresh onions are in season, canning them is a great way to preserve them for use all year long. Canned onions are ready to use right from the jar and can be added to soups, stews, casseroles, salsas and more. With a few simple steps, you can learn how to safely can fresh onions at home.

Why Can Onions?

Canning onions allows you to:

Preserve fresh onions to enjoy their flavor all year long
Save money by buying fresh onions in bulk when they are in season
Have diced, sliced or whole onions ready to use straight from the jar

Customize onions with added ingredients like salt, spices or vinegar
Make cooking and baking easier by having onions pre-prepped and ready to go
Reduce food waste by preserving onions before they go bad

Onions are low acid, so it is important to follow proper canning methods to prevent the growth of dangerous bacteria like botulism. When done safely, canning onions at home can provide a year-round onion supply.

Choosing Onions for Canning

You can can most types of fresh onions, but keep these tips in mind:

Choose firm, fresh onions with crisp outer skins and no signs of mold or damage.

Avoid onions that have begun to sprout or have soft spots.
Yellow, red or white onions all work well for canning.
Sweet onions like Vidalias can be canned but will lose some of their sweetness.

Strongly flavored onions like shallots are not recommended for canning.
Onions with thicker skins are better for canning whole. Thinner skinned onions are ideal for diced or sliced.
When in doubt, ask your local agricultural extension office for recommendations on the best onion varieties for canning.

Canning Equipment

These basic supplies are needed for canning onions:

Canning jars with lids and bands (always use new lids)
Rack to fit inside a canning pot

Canning pot with lid (a water bath canner or large stock pot will work)
Jar lifter
Bubble removal tool

Clean towels
Canning funnel (optional)

Ball and Kerr are two popular brands of mason jars made specifically for canning. The jars come in a variety of sizes like 4 oz, 8 oz and 16 oz. Choose the size that best suits your needs. Wide mouth jars make filling easier.

Prep the Onions

Start with fresh, firm onions within a couple days of purchasing. To prepare the onions:

Wash the onions under cool running water to remove any dirt. Do not soak.
Remove any loose or damaged outer layers. Trim the tops and root ends.

Peel off the outer skins. Try not to remove too many layers underneath.
Slice, dice or leave onions whole depending on your preference.
Place prepared onions in a clean bowl.

Onion Canning Options

Onions can be canned in a few different ways:

Whole – Leave small peeled onions whole.
Slices – Cut onions into slices about 1/4 inch thick.

Diced – Dice onions into 1/4 to 1/2 inch pieces.
Chopped – Finely chop peeled onions.
Caramelized – Cook down sliced onions until caramelized and deeply golden brown.

Choose the style that suits your cooking needs. Diced, sliced and chopped onions are easy substitutes for fresh in recipes. Whole baby onions work well in soups or stews. Caramelized onions add rich, sweet flavor.

Preparing the Onions for Canning

Raw pack method:

Place prepared raw onions into sterile canning jars, leaving 1 inch of headspace at the top. Press onions down to pack fairly tightly.

Optional: Add salt, vinegar or other flavorings to the jars. See seasoning ideas below.
Remove any air bubbles with a bubble tool. Add more onions to return to 1 inch headspace.
Wipe the jar rims with a clean, damp towel.

Center lids on the jars and screw on bands fingertip tight.

Hot pack method:

In a large pot, bring onions and 1/2 cup water just to a boil over medium-high heat. Reduce heat and simmer for 5 minutes.

Pack hot onions and cooking liquid into sterile jars leaving 1 inch of headspace.
Optional: Add salt, vinegar or other seasonings to the jars. See seasoning ideas below.
Remove air bubbles, wipe rims and apply lids as above.

The hot pack method helps soften onions and removes air resulting in less floating and more compact jars. However, raw pack is fine too.

Onion Canning Seasoning Ideas

Try adding these ingredients when packing onions for extra flavor:

1/2 teaspoon salt per pint jar

1 teaspoon sugar per pint jar
Herbs like dill, basil or thyme
Spices such as peppercorns, chili flakes or cumin

2 tablespoons vinegar or lemon juice per pint jar
Onion or garlic powder
Pepper rings or jalapeño slices

Get creative with the additions! Almost any herb, spice or seasoning will work.

Processing the Onion Jars

Onions are a low acid vegetable, so it is critical to use a pressure canner for safe processing. Do not attempt to water bath can them.

Here are general pressure canning guidelines for onions:

Dial gauge pressure canner: Process jars at 11 PSI.
Weighted gauge pressure canner: Process jars at 10 pounds pressure.
Process pint jars for 40 minutes, quart jars for 45 minutes.

Let pressure drop naturally. Wait 5 minutes then remove jars.
Always follow your specific canner instructions for pressure levels and time.

Consult a reputable canning guide like the Ball Blue Book or National Center for Home Food Preservation for detailed onion canning information. Adjusting processing times and pressure for your altitude is very important.

Cooling and Storing Canned Onions

After removing jars from the pressure canner:

Allow jars to cool undisturbed for 12-24 hours.
Check jar seals by pressing on the center of each lid. It should not flex up and down at all.

Remove bands. Wash, dry and label sealed jars.
Store in a cool, dark place. For best quality, use within 1 year.
Unsealed jars with loose lids should be refrigerated and used within 2-3 days.

As the jars cool, you should hear popping sounds as the vacuum seals form. Test seals carefully before storing. If a jar did not properly seal, refrigerate and use it right away.

How to Use Canned Onions

Canned onions are ready to use in any recipe calling for onions. Ways to use them include:

Sauté into meat, egg or vegetable dishes

Add to soups, stews, chilies and casseroles
Put on pizzas, tacos, sandwiches and burgers
Include in fresh and pickled salsas

Mix into potato and pasta salads
Stir into dips and sauces like hummus, guacamole and cheese sauce

Drained canned onions can be used right away since they are already cooked. For extra flavor, quickly sauté or caramelize them before adding to a recipe.

Onion Canning Troubleshooting

Use these tips to prevent common onion canning issues:

Cloudy jar liquid – This is natural and caused by converted starches. It is not harmful.
Floating onions – Pack onions tightly and remove air bubbles to prevent floating.

Dark onion edges – Minimize peeling of onion layers to reduce dark edges.
Soft onions – Use firm, fresh onions and peel gently to avoid softness.
Musty odor/flavor – Process for full recommended time to destroy odor-causing microbes.

Metal taste – Use non-reactive pans and add a bit of vinegar when cooking onions.
Mold – Always use freshly cleaned and sterilized equipment. Check jar seals. Discard any moldy jars.

Carefully following onion canning best practices helps avoid most issues. Only can firm, fresh onions and process properly.

Frequently Asked Questions About Canning Onions

1. Is it safe to can onions in a water bath?

No, a pressure canner must be used when canning onions. They are a low acid vegetable which creates an environment where the botulism bacteria can grow. Use of a pressure canner ensures the contents reach 240°F, high enough to kill any botulism spores.

2. How long will canned onions last?

If stored in a cool, dark place, properly processed and sealed canned onions will last 12 months or longer. Over time, they may start to soften or develop a slight metallic taste but they remain safe to eat. Always inspect jars before use and discard any with mold, rust, bulging lids or leakage.

3. Can I use onion powder instead of fresh onions for canning?

Onion powder is heavily dehydrated so it is not recommended for canning recipes. For best quality and safety, always start with fresh onions. Onion powder could be added as a seasoning along with other dry spices when packing the jars.

4. Why did my canned onions turn blue or green?

A blue or green color in canned onions is natural and caused by compounds in the onions reacting with the acids, metals and sulfur compounds present. It is more common with white onions. The color change is harmless and does not affect the safety or flavor.

5. What type of onion is best for canning?

Yellow, red and white onions all work equally well. Choose onions that are firm and fresh with crisp outer skins. Avoid thicker specialty onions like shallots or sweet onions like Vidalias which can turn mushy when canned. Smaller onions are easiest for packing whole.

Tips for Successful Onion Canning

Here are some top tips for safely canning fresh onions at home with great results:

Select firm, fresh onions free of soft spots and sprouting.
Handle onions gently during peeling and prep to avoid bruising.
Pack onions tightly into jars leaving 1 inch headspace.

Remove air bubbles and add more onions to maintain headspace.
Use a pressure canner and dial/adjust to the proper PSI for your altitude.
Process pint or quart jars for full recommended time based on canner type.

Allow jars to seal and cool undisturbed for 12-24 hours.
Check all jar seals before storing.
Refrigerate and use promptly any unsealed jars.

Following the detailed instructions in a trusted canning guide along with these tips will help ensure safely canned onions to enjoy for months to come.

Conclusion

Canning is a great way to enjoy fresh onion flavor all year round. When done safely using a pressure canner, low acid foods like onions can be preserved at home with successful results. Choose quality onions, prepare using your preferred method, pack tightly into jars, process properly and test seals. In no time you’ll have a pantry stocked with onions ready to enhance soups, salsas, casseroles and more. Canned onions are also delicious gifts for other home cooks. With the simple steps outlined, you’ll see how rewarding and budget-friendly canning onions can be.