12 Common Beginner Canning Mistakes (and How to Fix Them)

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Canning mistakes are easy to make, and often just as easy to fix, provided you know how to troubleshoot.

The following was contributed by Bethany at Family Growing Pains. Bethany blogs about gardening, home preserving, and raising backyard chickens on her small homestead.

Once you dive into the world of gardening and growing your food, learning how to can the food that you produce is the next logical step. Too many people stop before making that step, afraid of canning. If you can make a recipe, then you’ll be able to learn how to can. First, take a look at these common canning mistakes, so when you finally make your first batch, it’ll be successful.

Common Beginner Canning Mistakes

I remember the first time I decided I wanted to try canning. My first attempt at canning was making a batch of strawberry jam – a classic first-timer recipe. I was so nervous, and I wasn’t even using a pressure canner.

Oh boy, the first time I used a pressure canner, I was full of nerves. Everyone has heard of horror stories about pressure canners blowing up. I grew so many green bean plants that I knew I had to can them, but you need a pressure canner for vegetables. 

It turns out that it wasn’t as bad as I expected, and nothing exploded, but I still made plenty of mistakes. I had liquids siphon out, lids not seal, jars shatter, and jams not set. Part of canning is making mistakes and learning from them. 

Let’s look at some of the most common canning mistakes and how you can fix them in the future. No use making the same mistake twice!

Using a Water Bath Canner When You Need a Pressure Canner

First, you have to know when to use a water bath canner, often called a roiling water bath, and when to use a pressure canner. Failing to use a pressure canner when it’s needed is a dangerous mistake. 

Here’s how you know which method to use. 

Acidic foods may be canned in a boiling water bath. You don’t need any special equipment; it requires a large stockpot that you can submerge canning jars, lids, canning jars, and the food you want to preserve. 

Examples of foods you can preserve in a boiling water bath: 

• Pickles
• Jams
• Jellies
• Salsa
• Tomatoes (with added acid)

Non-acidic foods require a pressure canner, which is NOT a pressure cooker. You need a pressure canner because these foods have a higher risk of containing bacteria, and the pressure is required to kill off the spores. If you fail to use the right equipment, you increase the risk of botulism, which can kill you.

Examples of foods that require a pressure canner include:

• Vegetables (not pickled)
• Soup
• Chicken Broth
• Meat
• Dry Beans (Pinto, Black Beans, etc)

Overfilling Jars (Not Using Propper Headspace)

When you read a safe canning recipe, it will tell you how much headspace to leave at the top of the jar. Depending on what you’re canning, the recipe might indicate any amount from one inch to half of an inch.

Headspace is the space between the surface of the food and the rim of the jar. If you fill your jar too much, the lids might not seal properly. Also, failing to leave the proper headspace might cause the liquids to siphon out, spilling over the side. That can cause a bad seal on your jars. 

Of course, an unsealed jar isn’t the worst thing; it can happen without making any mistake. You can eat the food immediately or put it in the refrigerator and eat it within a week. Multiple unsealed jars are a big deal, so always leave the correct headspace. 

All inexperienced canners WILL make this mistake, myself included. I remember several tomato sauce jars that didn’t seal because I overfilled my jars and ignored the recommended headspace. 

Don’t panic, and don’t give up canning. This is easy to fix! You can buy a headspace measurer, or my preference, a canning funnel with headspace measurements, to ensure you have the right measurement before putting the jars into the canner. 

Reusing Canning Lids

Canning lids are not meant to be reused. The adhesive rubber on the underside of the lid wears out fast, so while you might be able to reuse and reseal them again, there is no guarantee that the seal will stick. 

Once again, it’s not worth the price of having multiple unsealed jars, especially since canning lids rarely cost more than $3 per box. Save the used lids in a separate bag; I use them for leftovers that I store in the refrigerator. 

The exception to this rule is Tattler reusable canning lid. These lids are meant to be reusable with interchangeable rubber seals. 

Not Looking for Cracks or Chips in the Jars 

Always inspect all of your canning jars before filling them with hot food. All it takes is a hairline crack for the jar to crack when you put it into the canner. That leads to entire jars of wasted food; no one wants that. 

I do the inspection when I scrub and clean the jars. Turn it over in your hand, looking for chips along the rim (which is common) and cracks along the sides. 

Sometimes, even when we inspect the jars, we miss something; these are glass after all! Try your best to examine carefully. 

This jar of home-canned carrots had a chip down near the bottom, and that blew out in the pressure canner.

Not Using Hot Jars 

Siphoning is a common canning problem with fruit and tomato products, but it does happen with vegetables and meats. This is the loss of liquid around the edges of your jar. Aside from not using the appropriate headspace, not using hot jars is one of the most common canning mistakes. 

Loss of liquid happens commonly when there is an extreme temperature difference. Preheating your jars before filling puts hot food into hot jars, and then you stick it into a hot canner. Not only does this reduce siphoning, but it also reduces the risk of breaking a jar. 

There are several ways you can heat your jars. If you time it right, you might be able to run them through the dishwasher and take them out during the drying phase. If you’ve ever tried to take a jar out of a dishwasher prematurely, you know that those cups are HOT. 

If you’re using a boiling water bath, you can put the jars into the water and keep the lid on as the water heats up. Another option is to put your freshly washed jars in a bowl or the sink and cover them with hot water. Try adding water from a kettle to increase the temperature. 

In the worst case, cold jars will actually break in the canner.  A break along the bottom seam of the jar is a classic case of thermal shock…

Leaving the Air Bubbles in the Jar 

So, you read the instructions on all the websites about how to can foods and know that you’re supposed to move a bubble popper or butter knife around the jar to help burst air bubbles. It seems like a waste of time, so why not skip this step?

Don’t skip it; it only takes a few seconds for each jar, but those air bubbles add more – you guessed it – air to your jar. Not only does that potentially add more air in your headspace leading to a bad seal, but it also could lead to spoilage. Air bubbles give space for bacteria to live. 

Forgetting to Wipe the Edges of the Jar

I think one of the essential steps of canning is wiping the edges of the jar. When you fill the jars with whatever you’re cooking, bits and pieces end up on the edges. If you don’t wipe down the edges and put the lid over the top of these bits of food, the lids won’t seal. 

This is an easy canning mistake to fix. Take a wet rag or paper towel and wipe the jar’s edges before placing the lid on top and screw on the rings. If you make it part of your canning routine, you’ll never forget to do it. 

(Here’s I’m quickly pouring homemade blackberry jam into a jar…because I can’t find my funnel.  That’s a recipe for a messy rim, but wiping up after solves that.  Using a canning funnel helps keep the jar rims clean, but it’s not a complete solution, be sure to still wipe the rims to ensure a good seal.)

Failing to Adjust Canning Time or Pressure Based on Your Altitude

When you look at most canning recipes, it shows canning times or canning pressure based on your altitude. If you live more than 1,000 square feet above sea level, you have to adjust these because the water won’t boil at the same temperature at higher altitudes than at sea level. 

Making adjustments of either the canning time or pressure makes up for the difference in altitudes. Your food won’t be preserved safely without the change. 

Not Adding Enough Water to the Canner

Both roiling water baths and pressure canners require water. When adding water to a pressure canner, look for indentations on the interior sides and fill up to these markers. Your canner manual will help you figure out how much water is needed for your particular model.

When using a boiling water bath, the lids must be covered by two inches of water or more. This step is necessary because it heats the food evenly on all sides of the jar. 

Taking Jars Out of the Canner Too Soon

You did it! You canned your first thing, and you’re ready to see the finished product. As soon as the timer goes off, you remove the jars from the canner and smile at what you made. 

Most of the time, when you do this, nothing wrong will happen, but leaving the jars in the canner after processing time ends with the heat turned off reduces the risk of siphoning. Let the batch of jars sit in the canner for five minutes before removing them and placing them on a dishtowel. 

If you’re pressure canning, turn off the heat but leave the lid on it. It has to reduce heat naturally and unlock when all of the pressure leaves. Once your canner lid opens and you can safely remove the lid, take it off and let the jars sit for 10 minutes inside of it. 

Disturbing Jars Too Quickly 

When I remove the jars from the canner, I place them on my kitchen counter with a dishtowel underneath the jars. The recommendation is to allow your jars to cool for 12-24 hours before disturbing, allowing the contents to cool completely.

Why?

Most lids seal well before the cooling process ends, but some do need longer. If you disturb jars too early, it might break the developing seal by moving the hot food in contact with the lid’s adhesive part. 

Storing the Jars with the Rings On

The last of the canning mistakes you don’t want to make is storing the canned food with the rings still on the jars. It’s an easy mistake to make. After letting the jars rest on the counters for 24 hours, label and store them away. You might not even think about the rings.

What’s problematic about storing jars with the rings still on?

Even with the rings on, the lids can loosen up and come unsealed, allowing air and bacteria to enter under the lid. That can lead to spoilage, which is hidden by the rings still kept on the jars. In some cases, the pressure from the rings might cause the lids to reseal. 

Storing jars with the rings off makes it easy for you to spot a jar with a bad seal. You’ll be able to take it right out of storage and toss it. Never eat food that came out of a jar with a bad seal; you have no idea when the seal loosened and what bacteria might live in the food. 

Beyond that, mold and rust are common under jar rings.  During canning, small amounts of liquid escape the jar and can become trapped under the ring…meaning that it stays moist and sugary under there.  A few months later, you might try to twist the ring only to find it stuck shut. (Or twist it off to find the threads coated in mold.)

Vacuum within the jars should be holding the lids on, as it is with these home-canned strawberries, rather than the ring once processing is complete and the jars have cooled.

How to Fix Canning Mistakes

If you make canning mistakes, you CAN fix them if you catch the error quickly. Mistakes must be caught within 24 hours. If you figure out that you made a mistake and it’s within that time frame, go ahead and reprocess that.

Whatever you do, don’t forget the 24-hour rule – it’s serious. After that, toss the food out – it’s not worth the risk of making you or your family member safe. 

Something to remember is that not all foods handle reprocessing. I’ve messed up several batches of jellies and jams; those handle reprocessing well. Usually, I simply need to add more pectin or sugar to make the right consistency.

However, reprocessing home canned green beans? That would turn them into a mushy bean; I doubt I would want to eat those. Soft foods handle reprocessing the best.

Freeze What Doesn’t Reprocess Well

I know green beans don’t handle reprocessing well because I messed up a batch one time. Several of the lids didn’t seal, so I tried it again. Trust me, that texture in a casserole wasn’t something I want to try again.

Instead, you can freeze the food. You can freeze the food in jars but make sure to leave space for swelling when the food freezes. Another option is to put them in a freezer bag or container. I recently had one jar of sloppy joes not seal because I filled the jar a bit too much, so I took a bit out of the jar and put it in the freezer for a quick meal later. 

Start Canning!

Don’t be intimidated by these canning mistakes. Now that you know what you shouldn’t do, make sure you avoid them. Canning is much easier than you imagine, so stop stalling and give it a try today. You’ll wonder why you didn’t try preserving foods earlier.