How to Can Tomatoes

If you’ve been growing tomatoes all season long, you’re probably looking forward to harvesting and canning them. Canning tomatoes is a great way to preserve the fresh taste of summer throughout the year. Imagine having homemade spaghetti sauce, salsa, or stewed tomatoes at your fingertips whenever you need them.

Whether you’re new to the process or have canned before, this guide from Blain’s Farm & Fleet will walk you through every step of the way. From selecting the right tomatoes, preparing them for canning, and using both water bath and pressure canners, we’ll cover everything you need to know.

Step 1: Selecting and Preparing Your Tomatoes

For canning, it’s best to use paste tomatoes such as Roma, San Marzano, or Amish Paste types. These varieties have fewer seeds and a thicker flesh, making them ideal for preserving. Ensure your fresh tomatoes are ripe, firm, and free from blemishes.

Rinse the tomatoes under cold water to remove any dirt and pesticides. Using a paring knife, cut out the stems and core each tomato.

Bring a large pot of water to a boil. Dip the tomatoes in the boiling water for 30 to 60 seconds, until the skins start splitting. Then, immediately transfer them to an ice water bath. Once cooled, peel off the skins.

Step 2: Sterilizing Jars and Equipment

Gather your supplies. You’ll need:

• Mason jars with lids and bands
• Large pot or canner
• Jar lifter
• Wide-mouth funnel
• Bubble remover tool or non-metallic spatula
• Clean towels

Next, sterilize the jars. Clean the jars and lids thoroughly with soapy, hot water. Then, rinse well. Place the canning jars in a large pot of boiling water for at least 10 minutes to sterilize. Keep them hot until ready to use. This will prevent cracking when filling with hot tomatoes.

Step 3: Filling the Jars

You can can tomatoes whole, diced, or as a puree. For whole or diced tomatoes, place peeled tomatoes in a large pot and bring to a simmer. This helps eliminate excess air and ensures proper sealing.

For each pint jar, add one tablespoon of lemon juice or 1/4 teaspoon of citric acid to ensure safe acidity levels. This also helps seal in flavor and color. And more importantly, it decreases the risk of botulism.

Use a wide-mouth funnel to fill each jar with tomatoes, leaving about half an inch of headspace at the top. Slide a bubble remover tool or a non-metallic spatula around the inside edge of the jar to release trapped air.

Clean the jar rims with a damp towel to ensure a good seal. Place the lids on the jars, and screw on the bands until fingertip tight. The canner will tightly seal the lids and bands.

Step 4: Processing the Jars

When it comes to the canning process, you have a couple of options at your disposal. You can use a water bath canner or a pressure canner. With the addition of lemon juice or citric acid, both methods are safe.

Using a Water Bath Canner

1. Prepare the Canner: Fill your canner with enough water to cover the jars by at least one inch. Preheat the water to 180° F (for hot-packed foods).
2. Place Jars in Canner: Use a jar lifter to carefully lower the filled jars into the canner.
3. Process Jars: Once the water returns to a rolling boil, process pint jars for 30 minutes and quart jars for 40 minutes. Adjust the time if you live in a high altitude.

Using a Pressure Canner

1. Prepare the Canner: Add about two to three inches of water to the pressure canner.
2. Place Jars in Canner: Use a jar lifter to place the jars in the canner, ensuring they’re evenly spaced.
3. Seal the Canner: Secure the lid according to the manufacturer’s instructions.
4. Vent Steam: Allow steam to vent steadily for 10 minutes before placing the weight on the vent.
5. Process Jars: Process pint jars at 10 pounds of pressure for 20 minutes and quart jars for 25 minutes. Adjust for your altitude, if necessary.
6. Cool Down: Turn off the heat, and let the pressure return to zero on its own. Remove the weight, and wait another 10 minutes before opening the canner.

Cooling and Sealing

After processing, turn off the heat and let the jars sit for five minutes. Then, remove them using a jar lifter, and place them on a towel or wooden cutting board.

Allow the jars to cool undisturbed. As they cool, you’ll hear the “pop” of the lids sealing. After 24 hours, check that the lids have sealed properly. You can do this by pressing each one down in the center. If it doesn’t flex, the jar is sealed correctly.

Step 5: Storing and Enjoying Your Canned Tomatoes

Label each jar with the date and contents. Store them in a cool, dark place, such as a pantry or cellar. Properly canned tomatoes will last up to one year.

Troubleshooting and Tips

• Unsealed Jars: If a jar hasn’t sealed, refrigerate it and use within a week, or reprocess it with a new lid.
• Cloudy Liquid: This could be because of minerals in hard water. Using distilled water can help.
• Floating Tomatoes: Pack tomatoes firmly, and use proper headspace to minimize floating.

You have successfully canned your tomatoes! Now, they’re ready for you to enjoy in soups, sauces, and a variety of other recipes throughout the year. Remember to periodically check your stored jars for any signs of spoilage. And consume them within a year for the best quality.

For more how-to guides like this one, check out our other Canning articles.