How to Can Tomatoes

If your garden produces more tomatoes than you can eat, or you get a great deal on locally grown sun-kissed tomatoes, canning your own tomatoes is the perfect way to capture the flavor of summer. This beginner's guide for canning tomatoes will take you through the canning process step by step and answer all your canning questions.

There are two ways to can tomatoes: in a boiling water bath or in a pressure canner. A pressure canner is different from a pressure cooker, which is not safe for canning. Pressure canners have a dial gauge or a weighted gauge and a rack for the jars. They are also larger than pressure cookers and fit at least one layer of quart jars.

If you don't own a pressure canner, don't worry -- it is possible to can tomatoes without one. Water bath canning works too as long as you follow the instructions. And you don't need a water bath canner either; any pot large enough to cover the jars with at least one inch of water works.

Whichever canning method you choose, canning tomatoes always requires acidification to make them safe. If that is too involved for you, a third alternative is freezing tomatoes.

The following instructions are for canning whole or halved tomatoes packed in water with the hot-pack method, where the tomatoes are briefly cooked before canning them. You can also raw-pack tomatoes, but hot-packing has two major advantages: you can fit more tomatoes in a jar so there are fewer jars to process, and cooked tomatoes are less likely to float on top after processing because they contain less air.

How to Can Tomatoes

Supplies:

• Fully ripe tomatoes (about 1 1/2 pounds fresh tomatoes to fill a pint jar, and 3 pounds to fill a quart jar)
• Bottled lemon juice or citric acid powder
• Pint or quart canning jars with lids
• Pot with lid and trivet or pressure canner
• Jar lifter tongs

1. Inspect the Jars

Inspect the jars for any cracks or imperfections, including in the rim. Discard any damaged jars.

2. Place the Jars in a Canning Device

For water bath canning, use a water bath canner or place a silicone trivet or a rack in a large pot or stockpot so the jars won't sit directly in the bottom of the pot. Place the jars in the canner or pot and fill it with enough water so the jars are fully covered.

For pressure canning, add 2 inches of water to the pressure canner. Place the jars in the water and fill them with water.

3. Bring Water to Simmer

Slowly bring the water to a simmer while you prepare the tomatoes.

4. Wash and Cut Tomatoes

Wash the tomatoes and remove the stems. Using a paring knife, cut an X in the bottom of each tomato.

5. Blanch the Tomatoes

Bring a large pot of water to boil. Blanch a few tomatoes at a time in the boiling water, just long enough until the skin starts to curl up where you scored it, about 30 seconds depending on the size of the tomato.

6. Dip the Tomatoes in Ice Water

Remove the tomatoes with a slotted spoon and dip them in ice water. Then place them in a colander placed over a bowl to catch any excess liquid. When the tomatoes are cool enough to handle, remove the skins and cores. Cut large tomatoes in half.

7. Cook the Tomatoes

Return the tomatoes and liquid to the pot and cover them with water. Bring to a boil, then reduce the heat to medium-low and cook for 5 minutes.

8. Remove the Jars

Using the lifter tongs, remove the jars from the water bath canner/pot or pressure canner and dump out the water that's inside the jars. Keep the water in the canner/pot simmering. Place the empty jars on a damp tea towel to prevent them from cracking when you fill them with the hot tomatoes.

9. Add the Bottled Lemon Juice or Citric Acid

Add 1 tablespoon of bottled lemon juice or 1/4 teaspoon of citric acid to each pint jar, and 2 tablespoons of bottled lemon juice or 1/2 teaspoon of citric acid to each quart jar.

10. Fill the Jars With Tomato Mixture

Fill the jars with the hot tomato mixture and leave 1/2 inch of headspace. Push the tomatoes down to pack them tightly and remove any air pockets. The tomatoes should be fully immersed in liquid so add more of the cooking liquid as needed.

11. Wipe the Rims of the Jars

Wipe the rims of the jars with a damp paper towel to remove any drippings, which will prevent the jars from sealing properly.

12. Seal the Jars

Close the jars with new lids and bands.

13. Process the Jars

For water bath canning, place the jars back into the water bath canner/pot. They must be covered with at least 1 inch of water, so add more water if needed. Process pint jars for 40 minutes and quart jars for 45 minutes, always keeping the water at a steady gentle boil. If your altitude is above 1,000 feet, the tomatoes need to be processed longer.

For pressure canning, place the jars in the canner and follow the manufacturer's directions about venting the pressure canner.

In a dial-gauge pressure canner, process pint and quart jars at 11 pounds pressure for 10 minutes.

In a weighted-gauge pressure canner, process pint and quart jars at 10 pounds of pressure for 10 minutes.

14. Remove the Jars

After processing, when using a water bath canner, turn off the heat and leave the jars in the hot water for 5 minutes. This prevents a sudden change in temperature which can lead to liquid bubbling out of the jars even though they are sealed (this is called siphoning). Carefully remove the jars with the jar lifter onto a damp tea towel and let them cool and settle for 24 hours.

When using a pressure canner, let the canner fully depressurize before you open it. Remove the jars and let them cool and settle for 24 hours. Check the seal and remove the bands before storing the jars.

Canning Tomatoes FAQs

Q. Do I have to peel the tomatoes before canning?
A. Yes, it is necessary for food safety reasons as the skin harbors bacteria.

Q. Do I have to add lemon juice when canning tomatoes?
A. Yes, adding acid is absolutely necessary. And it must be bottled lemon juice, as fresh lemons vary in acidity.

Q. Can I use white vinegar for canning tomatoes?
A. You can but it creates an off-flavor. Citric acid or bottled lemon juice are more flavor-neutral options.

Q. Is it safe to can tomatoes in an Instant Pot or multi-cooker?
A. No, canning tomatoes in these devices is not safe.

Q. Is it safe to can tomatoes in the oven?
A. No, oven canning is not safe because of temperature fluctuations. Also, the jars can explode in dry heat.

Q. When canning, can I combine tomatoes and other vegetables?
A. Peppers, green chilies, onions, and garlic should not be canned together with tomatoes due to the lack of acidity of those vegetables unless you follow a tested recipe by an authoritative source such as the National Center for Home Food Preservation or Cooperative Extension.

Q. Is it possible to can tomatoes without liquid?
A. Yes, but the processing times and required pounds of pressure are different from canning tomatoes packed in water.

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