How to Can Tomatoes: A Comprehensive Guide to Home Preservation

Canning tomatoes is a rewarding way to preserve the fresh, vibrant flavors of summer, allowing you to enjoy your garden bounty or farmers market finds throughout the year. Whether you’re a seasoned canner or a beginner, mastering the art of canning tomatoes at home is simpler than you might think. This guide will walk you through everything you need to know about How To Can Tomatoes safely and effectively, using both boiling-water bath and pressure canning methods.

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For successful tomato canning, quality ingredients and proper preparation are key. You’ll need approximately 1¼ to 1½ pounds of ripe tomatoes for each pint jar, and 2½ to 3½ pounds for each quart. Select firm, unblemished tomatoes for the best results and wash them thoroughly under cold running water to remove any dirt or residue.

Once you have your tomatoes ready, you can choose how you want to can them. This guide provides detailed instructions for canning whole, halved, or crushed tomatoes, ensuring you can tailor the process to your preferences and future culinary plans. Get ready to unlock the delicious, garden-fresh taste of canned tomatoes all year long!

Discover the best tomato varieties for canning and freezing in your garden

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How to Can Tomatoes Using the Boiling-Water Bath Method

The boiling-water bath method is a safe and effective way to can tomatoes due to their natural acidity, especially when you add a touch of extra acidity. Follow these step-by-step instructions for successful boiling-water bath tomato canning.

Step 1: Sterilizing Your Canning Jars and Lids

Before you begin canning, sterilizing your jars and lids is a critical step to prevent spoilage and ensure a safe, shelf-stable product. Here’s how to properly sterilize your canning supplies:

Wash Jars: Start by washing your empty canning jars, screw bands, and new lids in hot, soapy water. Rinse them thoroughly to remove all soap residue.
Sterilize Jars: Place the clean jars in a boiling-water canner. Ensure the canner is tall enough to cover the jars with at least 1 inch of water above the tops.
Submerge in Water: Fill the canner with hot water, making sure the water covers the jars completely.
Simmer to Sterilize: Bring the water to a simmer over medium heat and let the jars simmer for 10 minutes. This sterilizes the jars by heating them to a temperature that kills harmful microorganisms.
Keep Jars Hot: After simmering, keep the sterilized jars hot in the simmering water until you are ready to fill them with tomatoes. This prevents them from cooling down and potentially becoming contaminated.
Prepare Lids: While the jars are sterilizing, prepare the lids. Place the new lids in a separate clean bowl and pour hot (not boiling) water over them, ensuring they are submerged. This softens the sealing compound on the lids for a better seal. Do not boil the lids as this can damage the sealing compound. Screw bands do not need to be sterilized but should be washed and kept clean.
Remove Jars One at a Time: When you are ready to fill each jar, use canning tongs to carefully remove one sterilized jar at a time from the hot water. Place it on a clean kitchen towel or a canning rack to prevent thermal shock and to provide a stable surface while filling.

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Step 2: Peeling Your Tomatoes

Peeling tomatoes before canning is recommended as tomato skins can become tough during the canning process and may detract from the texture of your canned tomatoes. Here’s a simple method for easily peeling large batches of tomatoes:

Prepare Tomatoes: Begin with firm, unblemished tomatoes. Wash them thoroughly in cold water to remove any dirt or debris.
Score the Bottoms: Using a paring knife, lightly score an “X” on the blossom end (opposite the stem end) of each tomato. This helps the skin split evenly during blanching.
Blanch in Boiling Water: Bring a large pot of water to a rolling boil. Gently lower a few tomatoes at a time into the boiling water using a slotted spoon or blanching basket. Blanch them for 30-60 seconds, or until you see the skins start to split open at the scored “X”. The time may vary depending on the ripeness and size of the tomatoes.
Ice Bath Shock: Immediately transfer the blanched tomatoes from the boiling water to a bowl of ice water. This rapid cooling stops the cooking process and helps the skins slip off easily.
Peel and Core: Once the tomatoes are cool enough to handle, peel off the skins starting from the scored “X”. The skins should slip off easily. After peeling, use a paring knife to remove the core (the hard stem end) of each tomato.
Cut Tomatoes (Optional): At this stage, you can decide how you want to can your tomatoes. For whole or halved tomatoes, leave them as they are or cut them in half. If you prefer diced tomatoes, now is the time to halve and then dice them into your desired size.

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Step 3: Filling Jars with Tomatoes and Adding Acidity

Properly filling your jars and adding the correct amount of acidity are crucial steps for safe tomato canning. Adding bottled lemon juice ensures the acidity level is high enough to prevent the growth of botulism-causing bacteria. Here’s how to fill your jars correctly:

Prepare Jars: Keep your sterilized jars hot. Place a wide-mouth canning funnel into the opening of a hot, sterilized pint or quart jar. The funnel helps to keep the jar rim clean and makes filling easier.
Fill with Tomatoes: Ladle the prepared tomatoes (whole, halved, or diced) into the jars. If you have accumulated tomato juices during the peeling and cutting process, include these juices in the jars as well for added flavor and liquid. Pack tomatoes into the jars, leaving the recommended headspace.
Add Lemon Juice: For each pint jar, add 1 tablespoon of bottled lemon juice. For each quart jar, add 2 tablespoons of bottled lemon juice. It is essential to use bottled lemon juice because its acidity level is consistent, unlike fresh lemon juice which can vary. Do not substitute vinegar for lemon juice as it can alter the flavor and is not recommended for increasing acidity in canned tomatoes for safety.
Add Boiling Water (Optional): If needed, add boiling water to the jars to fill any remaining space and to ensure the tomatoes are covered in liquid. Maintain a ½-inch headspace, which is the space between the top of the food and the rim of the jar. Headspace is crucial for proper sealing.
Remove Air Bubbles: After filling, use a clean utensil, like a non-metallic spatula or bubble remover, to gently release any trapped air bubbles from the jars. Run the utensil along the inside edge of the jar.
Check Headspace Again: Re-check the headspace after removing air bubbles. If necessary, add more boiling water to maintain the ½-inch headspace.

To ensure safety, it’s important to understand why acidity is crucial in tomato canning. Tomatoes are considered borderline high-acid foods. For safe boiling-water canning, the pH of the canned food must be 4.6 or lower to prevent the growth of Clostridium botulinum, the bacteria that causes botulism. Adding bottled lemon juice consistently lowers the pH, ensuring a safe canning process.

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Step 4: Sealing and Processing Jars in a Boiling-Water Canner

Once your jars are filled and lemon juice is added, the next step is to properly seal them and process them in a boiling-water canner. This heat processing step eliminates any remaining microorganisms and creates a vacuum seal, ensuring long-term preservation.

Wipe Jar Rims: Remove the canning funnel and carefully wipe the rim of each jar with a clean, damp cloth or paper towel. Ensure there are no food particles or moisture on the rim, as this can prevent the lids from sealing properly.
Apply Lids and Screw Bands: Place a lid on each jar, ensuring the sealing compound makes contact with the clean jar rim. Screw on a band until it is fingertip-tight. This means tightening it as much as you can with your fingertips, without forcing it. Overtightening can prevent proper venting during processing and may lead to seal failures.
Load Jars into Canner: Carefully place the filled and sealed jars into the boiling-water canner. Use canning tongs to lower each jar gently into the canner. Ensure the jars are upright and not touching each other to allow for proper water circulation.
Add Water: Add enough hot or boiling water to the canner to cover the jars by at least 1 inch. If the water level is insufficient, carefully pour in more boiling water.
Bring to a Boil and Process: Place the lid on the boiling-water canner and bring the water back to a rolling boil. Once boiling, start your processing timer. Process pint jars for 40 minutes and quart jars for 45 minutes at a full rolling boil. The processing time is crucial for ensuring the tomatoes are safely preserved.
Adjust for Altitude: If you live at an altitude above 1,000 feet, you need to adjust the processing time. For altitudes of 1,001 to 3,000 feet, process pint jars for 45 minutes and quart jars for 50 minutes. For altitudes of 3,001 to 6,000 feet, process pint jars for 50 minutes and quart jars for 55 minutes. For altitudes above 6,000 feet, process pint jars for 55 minutes and quart jars for 60 minutes.
Cool Down: After the processing time is complete, turn off the heat and remove the lid from the canner. Let the jars remain in the hot water for 5 minutes before removing them. This gradual cooling period helps prevent siphoning (loss of liquid from the jars) and allows the jar contents to settle.
Remove Jars and Cool: Using canning tongs, carefully remove the jars from the canner, lifting them straight up and out. Place the hot jars on a clean towel-lined surface or a cooling rack, leaving space between them for air circulation. Avoid placing hot jars directly on a cold countertop, as this could cause thermal shock and breakage. Let the jars cool undisturbed for 12 to 24 hours. As they cool, you should hear a popping sound as the lids seal.

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Step 5: Checking the Jar Seals and Storage

After your jars have cooled completely, it is essential to check if they have sealed properly. A proper seal is critical for the long-term safety and preservation of your canned tomatoes.

Check for Seal: After the jars are completely cool (at least 12 hours), check each lid for a proper seal. The center of a properly sealed lid will be concave (curved downwards) and will not flex or move when pressed.
Test the Seal: Gently press the center of each lid with your finger. If the lid is firm and does not pop up or make a clicking sound, it is properly sealed. If the lid flexes up and down or you hear a clicking sound, the jar is not sealed.
Unsealed Jars: For any jars that are not properly sealed, you have two options:
1. Reprocessing: You can reprocess the tomatoes within 24 hours. Replace the lid with a new, properly prepared lid and process the jar again for the full recommended time.
2. Refrigerate: Alternatively, you can store unsealed jars in the refrigerator and use the tomatoes within a few days. They are still safe to eat as long as they are refrigerated promptly and used within a short period.
Remove Screw Bands: Once you have confirmed that the jars are properly sealed, you can remove the screw bands. While bands are necessary for processing to ensure a good seal, they are not needed for storage and can rust over time if left on. Removing bands also makes it easier to detect a loss of seal during storage.
Wash Jars: Wash the outside of the cooled jars with soapy water and rinse to remove any sticky residue from processing. Make sure the jars are completely dry before labeling and storing.
Label and Date: Label each jar with the contents (e.g., “Whole Peeled Tomatoes”) and the date of canning. This helps you keep track of your inventory and ensure you use the oldest jars first.
Store in a Cool, Dark, Dry Place: Store your sealed and labeled jars of canned tomatoes in a cool, dark, and dry place, such as a pantry or basement. Proper storage conditions help maintain the quality and flavor of the canned tomatoes for up to one year. While canned goods are often safe to eat for much longer, optimal quality is best within 12-18 months.

How to Can Crushed Tomatoes

Canning crushed tomatoes is a fantastic way to prepare for making homemade sauces, soups, and stews throughout the year. The process is similar to canning whole tomatoes, with a slight variation in preparation.

Prepare Tomatoes: Wash, peel, and core your tomatoes as described in Step 2.
Quarter and Crush: Cut the peeled tomatoes into quarters. Place a portion of the quartered tomatoes into a large, heavy-bottomed pan, enough to cover the bottom of the pan.
Initial Crush and Heat: Using a wooden spoon or a potato masher, crush the tomatoes in the pan. Heat the crushed tomatoes over medium heat and stir until the mixture begins to boil.
Add Remaining Tomatoes: Gradually add the remaining quartered tomatoes to the boiling mixture, stirring constantly. Continue to heat and simmer for about 5 minutes, stirring frequently to ensure even heating.
Fill Jars: Fill hot, sterilized pint or quart jars with the hot crushed tomatoes, leaving ½-inch headspace.
Add Lemon Juice and Salt (Optional): Add 1 tablespoon of bottled lemon juice and ¼ to ½ teaspoon of canning salt to each pint jar, or 2 tablespoons of bottled lemon juice and ½ to 1 teaspoon of canning salt to each quart jar. Salt is optional but enhances flavor.
Process in Boiling-Water Canner: Process pint jars for 35 minutes and quart jars for 45 minutes in a boiling-water canner, following the altitude adjustments as described in Step 4.
Check Seals and Store: Follow Step 5 to check for proper seals and store your canned crushed tomatoes.

How to Can Tomatoes with No Added Liquid

For a richer, more concentrated tomato flavor, you can can tomatoes without adding extra liquid. This method relies on the tomatoes’ natural juices to create the canning liquid.

Prepare Tomatoes: Wash and peel your tomatoes, halving or quartering them if desired.
Fill Jars Tightly: Pack the prepared tomatoes tightly into hot, sterilized pint or quart jars, pressing down gently to release their juices and fill any air spaces. Leave ½-inch headspace.
Add Lemon Juice and Salt (Optional): Add 1 tablespoon of bottled lemon juice and ¼ to ½ teaspoon of canning salt to each pint jar, or 2 tablespoons of bottled lemon juice and ½ to 1 teaspoon of canning salt to each quart jar.
Process in Boiling-Water Canner: Process pint and quart jars for a longer duration of 85 minutes in a boiling-water canner. Remember to adjust processing time for altitude as needed.
Check Seals and Store: Check for proper seals and store as described in Step 5.

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Pressure Canning Tomatoes for Added Safety

While boiling-water canning is generally safe for tomatoes when properly acidified, pressure canning offers an alternative method, especially for those seeking an extra margin of safety or canning stewed tomato products. Pressure canning heats the tomatoes to a higher temperature, which is particularly beneficial for lower-acid foods, though tomatoes are still considered high-acid enough for boiling water bath with added acid.

Prepare Jars and Tomatoes: Sterilize jars, lids, and screw bands as outlined in Step 1. Prepare tomatoes by peeling them and filling jars as described in the “How to Can Tomatoes with No Added Liquid” method. Remember to add bottled lemon juice to each jar for acidification.
Pressure Canning Process: Follow the manufacturer’s instructions for your specific pressure canner model. Generally, this involves:
- Add Water to Canner: Pour the required amount of water into the pressure canner.
- Load Jars: Place filled and sealed jars onto the canner rack, ensuring they are not touching each other or the sides of the canner.
- Seal Canner: Securely close and lock the pressure canner lid.
- Vent Canner: Vent the canner by allowing steam to escape from the vent pipe for 10 minutes to remove air, which ensures proper pressure and temperature inside.
- Pressurize: Close the vent (usually by placing a weight or closing a valve, depending on your canner model) and bring the canner to the required pressure.
- Process at Correct Pressure and Time: For canning tomatoes in a pressure canner:
  - Weighted-Gauge Pressure Canner: Process pint and quart jars for 40 minutes at 5 pounds PSI if you are at or below 1,000 feet above sea level. If you are above 1,000 feet, process at 10 pounds PSI for 40 minutes.
  - Dial-Gauge Pressure Canner: Process pint and quart jars for 40 minutes at 6 pounds PSI if you are at or below 2,000 feet above sea level. Adjust pressure for higher altitudes: 7 pounds PSI for 2,001-4,000 feet, 8 pounds PSI for 4,001-6,000 feet, and 9 pounds PSI for 6,001-8,000 feet.
- Depressurize: Once the processing time is complete, turn off the heat and allow the pressure to drop naturally until the pressure gauge reads zero and the canner is fully depressurized. Do not force cool the canner.
- Cool and Check Seals: Carefully remove the lid, lift out the jars using canning tongs, and place them on a towel-lined surface to cool completely. Check for seals and store as described in Step 5.

Whether you choose boiling-water bath or pressure canning, preserving tomatoes at home is a worthwhile endeavor. If canning isn’t an option, consider freezing tomatoes or exploring other tomato preservation methods like making and canning tomato sauce or salsa.

Knowing how to can fresh tomatoes empowers you to enjoy the taste of summer throughout the year, especially if you’re growing your own home-grown tomatoes.

How to Can Stewed Tomatoes

Canning stewed tomatoes is a convenient way to prepare a flavorful base for future recipes like pasta sauce or hearty soups. This recipe uses a pressure canner for safe processing due to the addition of lower-acid vegetables.

Prepare Tomatoes and Vegetables: Start with 8 pounds of ripe tomatoes. Wash, peel, remove stem ends and cores from tomatoes, and chop them. You should have approximately 17 cups of chopped tomatoes. Chop 1 cup of celery, ½ cup of onion, and ½ cup of green bell pepper.
Combine Ingredients: In a large 8- to 10-quart Dutch oven or kettle, combine the chopped tomatoes, celery, onion, and green bell pepper. Add 2 teaspoons of sugar and 2 teaspoons of canning salt.
Simmer Stew: Bring the mixture to a boil over medium-high heat, then reduce heat to low. Cover and simmer for 10 minutes, stirring frequently to prevent sticking and scorching.
Fill Jars: Ladle the hot stewed tomatoes into hot, clean pint or quart canning jars, leaving 1-inch headspace. Wipe the jar rims and adjust lids and screw bands to fingertip-tight.
Pressure Can Stewed Tomatoes: Process in a pressure canner at 10 pounds pressure for 15 minutes for pint jars and 20 minutes for quart jars. Ensure you adjust pressure according to your altitude and pressure canner type as per manufacturer’s directions.
Cool and Store: Allow the pressure to come down naturally in the canner. Once depressurized, remove jars, check for seals, and let cool completely before labeling and storing as described in Step 5.

Get the complete Stewed Tomatoes Recipe

By following these detailed steps, you can confidently can tomatoes at home and enjoy the taste of summer’s harvest all year round. Happy canning!