Adventures in Canning: Whole Tomatoes in Hot Water Bath

If I were to write a book called “100 Things You Should Know How to Do,” canning and gardening would be near the top of the list.

There is a certain satisfaction you get with growing and canning your own food and being able to enjoy the fruits (and vegetables) of your labor. Unfortunately, most of us know very little (if anything) about canning (myself included) and find ourselves relying on grocery stores to supply the food we need. But in these uncertain times, we cannot afford to remain ignorant on this topic. There may come a day when we need to can and grow our own food.

I won’t go into detail about how home-grown food tastes better than store bought food, or how it is healthier than food loaded with preservatives, or how it is less expensive than going to the grocery store. But I will share with you my very first adventure in canning whole tomatoes, and I hope with these helpful tips/instructions, you will be able to can your own tomatoes! 🙂

First start with fresh tomatoes. Avoid tomatoes that are squishy, overripe, moldy, or with areas of decay.


Fresh tomatoes from a farmers market

Next, wash the tomatoes. Cut an ‘x’ on the top section of the tomatoes before dropping them into a pot of boiling water for approximately 45 seconds. Boiling the tomatoes for 45 seconds makes it easier to peel the skins off.


Cut an ‘x’ on the tomatoes before boiling to make peeling off the skins easier

After boiling the tomatoes in hot water for 45 seconds, immediately place the tomatoes in cold water. This process is known as blanching. Immersing the tomatoes in a sink of cold water works just as well as a pot of cold water. The cold water quickly cools the tomatoes. You are now ready to peel off the tomato skins. The skins should just slide off the tomatoes, but paring knives work well for stubborn patches of skin. Finally, cut the tomatoes in half or quarter-sized pieces if desired.


Can tomatoes whole, in halves, or in quarter-sized pieces

Pack tomatoes into quality (ex: Ball, Mason) canning jars (pint-sized, quart-sized, etc.) but make sure each batch consists of the same sized jars. I packed my tomatoes into pint and a half sized Ball Jars.


Make sure the lip of the jar is smooth and even, otherwise it may not seal properly.

You will want to sterilize these jars before filling them with tomatoes. You can do this by either washing them in a dishwasher immediately prior to filling with tomatoes or by placing the jars in boiling water for 10 minutes. Many dishwashers have a sterilize setting you can use.


Dishwasher used to sterilize cans, lids, and bands

Using a funnel makes it easier to pack in the tomatoes without getting excess juice on the rim of the jar. A sterile utensil may be used to pack the tomatoes into the jar as well as to get rid of excess air bubbles along the sides of the jar. Getting rid of as much air as possible in the jars is crucial to prevent bacterial growth once the canning process is complete.


Getting rid of air bubbles on the sides of the jar

There are two ways to pack the whole tomatoes into the jars. The first is to allow the tomatoes’ own juice to help fill the jars and eliminate air bubbles as you pack them in tightly (but not too tightly!), and the second is to add boiling water to fill the air space after gently packing in the tomatoes. I used the first method because water can cause the tomatoes to lose some of their vibrant flavor. Make sure to leave half an inch of air space at the top of the jar. This space is needed to facilitate suctioning once the jars are placed in the hot water bath. If you are short on tomatoes/tomato juice, you can add boiling water to the jar to fill up the extra space.

Half an inch of space left at the top of the jar.

Half an inch of space left at the top of the jar

Tomatoes are considered a low acid food. Low acid foods have a pH that is greater than or equal to 4.6. Canning low acid foods requires more caution because dangerous microorganisms thrive in low acidic environments.

Clostridium botulinum

Clostridium botulinum

Clostridium botulinum is one such dangerous bacterium that thrives in moist, anaerobic (absence of air) conditions, producing a toxin that once ingested causes widespread paralysis that leads to death. Improper canning of low acid foods can cause the dangerous growth of Clostridium botulinum and other dangerous microorganisms.

Tomatoes are considered low acid food because their acidity varies with their maturity. For example, tomatoes are most acidic when they are unripe, but their acidity level decreases the more they ripen. Therefore, it is highly recommended to add acidity to your canned tomatoes.

Image from Google, pH of fruits & vegetables

Image from Google, pH of fruits & vegetables

2 tablespoons of bottled (not fresh) lemon juice or 1/2 teaspoon of citric acid is recommended per quart of canned tomatoes. 1 tablespoon of bottled lemon juice or 1/4 teaspoon of citric acid is recommended per pint of canned tomatoes. Since I canned my tomatoes in pint and a half jars, I added 1.5 tablespoons of lemon juice. Bottled lemon juice can be added either before or after the jars are filled with tomatoes. You can also add 1 teaspoon of salt per quart to help preserve your canned tomatoes.

Bottled lemon juice to increased acidity (lower pH) and salt preservative

Bottled lemon juice to increased acidity (lower pH) and salt preservative

Once you have filled the jars with tomatoes while making sure you leave 1/2 inch of headspace at the top, removed the excess air bubbles in the liquid, and added bottled lemon juice and salt, you are now ready to put on the lids and bands. Sterilize the lids and bands in boiling water for 2-5 minutes.

Sterilize the lids and bands in boiling water for 2-5 minutes

Sterilize the lids and bands in boiling water for 2-5 minutes

Then, before putting the lids on the jars, dip a cloth in hot water and wipe the lips of the jars to ensure a smooth and clean surface. Place the sterilized lids and bands on the jars and then lower the jars into the boiling water bath. Try to keep the jars from touching each other when lowering them into the water bath, and make sure the jars are covered by at least 1-2 inches of water at all times. Keep the water bath at a rolling boil for the required time (varies depending on altitude). I boiled my tomato jars for 90 minutes. If at any point the water stops boiling during the water bath, you must restart your time.

Find your elevation at

© United States Department of Agriculture

© United States Department of Agriculture

Once your hot water bath is complete, remove your cans from the hot water bath and place them on a towel over a hard surface, spacing the jars at least 1 inch apart from each other to allow air to evenly cool the jars. Allow the jars to cool, undisturbed, for a period of at least 12 hours. As the jars cool, this will further create a vacuum, causing the lids to cave inward and seal the tomatoes.

After the 12 hours are over, check your seal by pushing down on the top of each jar. The top shouldn’t budge. If it pops in and out, the seal is broken and the jar needs to be put in the fridge and eaten within the next few days. Another way to check the seal is to tap the top with a spoon. A dull sound may mean it has not sealed properly or that tomatoes/liquid are touching the top from inside. A ringing sound indicates the seal is intact. Lastly, hold the jar eye level to check if the top is curving inward. If the top is flat or bulges outward, the seal may be broken.

I hope you enjoyed my article! This was my first time canning whole tomatoes, so I still have a lot to learn. Any tips/suggestions are welcome!



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