How To Can Diced Tomatoes – A Great Way To Preserve Tomatoes

Once you learn how to can diced tomatoes you will be able to enjoy the delicious taste of garden fresh tomatoes any day of the year.

Every year, as our garden tomatoes begin to ripen, we begin the process of preserving the harvest through canning and freezing various recipes.

We use our tomatoes to make salsa, pasta sauce, ketchup, tomato juice, tomato sauce and more. But one of our favorite ways to preserve them is to make diced tomatoes and can them in pint jars.

Then, whenever a recipe calls for a can of diced tomatoes, I go to the canning pantry and pull out a pint jar that was made from the tomatoes in our garden.

But best of all, this is an easy canning recipe that even a beginner could master.

There are no complicated ingredients and no worries of balancing a mixture of vegetables and worrying if the pH level is safe for canning.

Although you have to follow the below guidelines for safe canning, the actual recipe requires only the following ingredients: tomatoes and bottled lemon juice.

That is it! And when you are ready to can the tomatoes, simply place them in mason jars and process them in a hot water bath canner.

If you are new at canning, we recommend this Water Bath Canner. We have one just like it and have been using it for years and absolutely love it!

However, we also understand that not everyone has the equipment for canning but would still like to preserve their fresh tomatoes. In that case, be sure to check out our article on How To Freeze Tomatoes.

How to Can Diced Tomatoes

*Complete recipe instructions including specific measurements, cook temperatures and times are located in a printable recipe card at the bottom of this article. However, be sure to keep reading for helpful tips and tricks when making this recipe.

*Makes approximately 9 pint jars

INGREDIENTS:

• 25 lbs of fresh paste tomatoes (about 1/2 bushel)
• Bottled lemon juice 

What Type of Tomatoes To Use…..

The first step in canning diced tomatoes is to pick or purchase your tomatoes. The best tomatoes to use for this recipe are paste tomatoes.

You will commonly find these varieties labeled as Roma, Amish Paste, or San Marzano. They are ideal to use because they have thicker walls, thin skin and an easy to remove seed core.

Although you can add a few slicing tomatoes to the mixture, it is recommended that you use no more than 25% of these type of tomatoes when canning diced tomatoes.

The reason is that these type of tomatoes will produce a large amount of liquid and you will end up with a large amount of tomato juice instead of chunks of tomatoes.

But the most important guideline to follow is to save your low-acid tomatoes for other recipes and do not use them in this recipe.

Standard tomatoes can be canned safely with their natural pH level along with a little added lemon juice. On the contrary, low-acid tomatoes are not safe to can without formally testing the pH level of each batch.

Therefore, use those variety of tomatoes to slice and eat. Or you could also make and freeze tomato soup, chili or tomato sauce instead.

INSTRUCTIONS

Now that you know what type of tomatoes to use it is time to get started! First, fill 1/2 of a large stockpot with water and bring it to a rolling boil.

In another large bowl add enough ice and water that it fills the bowl 75% full, then set it aside. 

Working in batches, place the tomatoes in the boiling water for one minute. Then use a slotted spoon or spider net to remove the tomatoes and place them in the ice water bath for 1-2 minutes.

Repeat the process until all the tomatoes have been blanched and iced down.

When the tomatoes are cool enough to be handled it is time to peel off the skins. Make a small slit on either end of the tomato.

Then use a pairing knife to peel the skin off the tomato. It should peel off easily. Repeat this process until all the tomatoes have their skin removed.

Next, slice the tomato in half lengthwise. Then remove the seed core by scooping it out with a spoon or squeeze the tomato over a large bowl.

Now it is time to cut the tomatoes into desired chunks. I prefer to dice them into cubes that are roughly 1/2 inch in size. However, you can make them as small or large as you would like.

When the tomatoes are ready it is time to prepare for the canning process.

The Canning Process

Start by sterilizing pint size canning jars. Most dishwashers have a sterilize function that you can use for your mason jars.

However, you can also sterilize them in the hot water bath canner itself. First, fill the mason jars with hot water and place on the rack in the pot.

Then fill the pot with water until it reaches the top of the jars. Bring the pot to a low simmer over medium-high heat.

As the jars are being sterilized, place 1/6th of the diced tomatoes in a large stockpot and place over medium-high heat. As the tomatoes begin to heat up, crush them with a wooden spoon or potato masher to release their juices, stirring frequently.

Once the crushed tomatoes come to a boil, add in the remaining diced tomatoes and stir. Then bring the mixture back up to a boil and continue to boil for 5 minutes. 

Using a jar lifter, pick up a pint jar and dump the hot water back in the water bath canner. Then place the jar on a kitchen towel next to the boiling tomatoes.

Fill The Jars

Pour the hot diced tomatoes into the jar, adding enough liquid to cover the tomatoes. Half way through filling the jar, add the bottled lemon juice and then continue to fill the jar leaving 1/2 inch head space for expansion.

Use a plastic knife to remove any air bubbles by sliding it down the inside of the jar. Then wipe the rims of the jars and place a canning lid on top.

Add the band and tighten to finger tight only.

Place the jar back in the hot water bath canner, and repeat the process until all jars are filled and placed back in the canner. Before canning, be sure that the water level is 1-2 inches over the top of the lids. 

Bring the hot water bath canner back to a rolling boil. Then set a kitchen timer for 35 minutes, adjusting the boiling time for altitude as needed. 

Once the diced tomatoes have been processed in the water bath canner for 35 minutes turn off the burner. Using a jar lifter carefully remove each jar and place on a thick towel to cool.

Let the jars cool for 24 hours. Then check the jars to see if they sealed properly by pressing on the center of the lid. A sealed jar lid will not move up and down.

If a jar did not seal properly place it in the refrigerator and use within 2 weeks. Store the sealed jars in a cool, dark place for up to one year.

Enjoy!

Mary and Jim

Jim and Mary Competti have been writing gardening, DIY and recipe articles and books for over 15 years from their 46 acre Ohio farm. The two are frequent speakers on all things gardening and love to travel in their spare time.

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