How To Water Bath Can Tomatoes: Whole & Diced

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What is Water Bath Canning?

Water bath canning is a method of preserving high-acid foods, like tomatoes, by processing them in boiling water. The heat kills off any bacteria and creates a vacuum seal that keeps your food safe and shelf-stable for years. This technique is perfect for tomatoes, which are naturally acidic. It’s a bit easier than pressure canning and doesn’t require specialized equipment—just a large pot with a rack and lid. For beginners, it’s the perfect way to dip your toes into the world of canning.

Equipment and Ingredients Needed

Equipment:

• Water bath canner (or large pot with rack and lid)
• Canning jars, lids, and bands
• Jar lifter 
• Funnel (for mess-free filling)
• Bubble remover or a butter knife (to release trapped air)
• Clean kitchen towels
• Slotted Spoon (for blanching)

Ingredients:

• Fresh, ripe tomatoes (any variety works!)
• Bottled lemon juice or citric acid (to ensure safety do not use fresh lemon juice)
• Optional: Canning salt (for flavor)

Preparing the Tomatoes Raw-Pack Method

This is my preferrd method for canning whole tomatoes.

1. Wash and Inspect: Start by washing your tomatoes thoroughly to remove any dirt. Inspect them for blemishes or bruises and discard any that are overripe or damaged.
2. Blanch and Peel: To remove the skins easily, blanch your tomatoes. Bring a pot of water to a boil, add the tomatoes for 30-60 seconds, and then transfer them to an ice bath. The skins should slip right off! If you don’t mind the skins, you can skip this step, but most people prefer their canned tomatoes skin-free.
3. Core and Dice (Optional): For whole tomatoes, remove the cores but leave them intact. For diced tomatoes, chop them into your desired size.

Preparing the Tomatoes Hot-Pack Method

This method is best for diced or halved tomatoes.

1. Wash and Inspect: Start by washing your tomatoes thoroughly to remove any dirt. Inspect them for blemishes or bruises and discard any that are overripe or damaged.
2. Blanch and Peel: To remove the skins easily, blanch your tomatoes. Bring a pot of water to a boil, add the tomatoes for 30-60 seconds, and then transfer them to an ice bath. The skins should slip right off! If you don’t mind the skins, you can skip this step, but most people prefer their canned tomatoes skin-free.
3. Core and Dice (Optional): For whole tomatoes, remove the cores but leave them intact. Chop diced tomatoes into your desired size.
4. Heat: Add water and cover the tomatoes in a large pot. Bring to a boil over medium heat and boil gently for 5 minutes.

How To Use A Food Mill For Tomatoes

If you want to skip the blanching and peeling steps, a food mill is an excellent tool for quickly processing tomatoes. This article explains how to use the best food mill for tomatoes. Keep in mind that the downside to using a food mill is that the finished product will have a smoother, puree-like consistency rather than a chopped or diced texture but does save a lot of time.

Step-by-Step Instructions

Sterilize Jars 

1. Wash Jars, Lids, and Bands: Begin by washing your jars, lids, and bands in hot, soapy water to remove any dirt or debris.
2. Choose Your Sterilization Method: There are several ways to sterilize jars. Select the method that works best for your kitchen, but ensure the jars remain hot to avoid thermal shock when filled with hot food and placed into boiling water during the water bath canning process.
   • Simmering Water: Place the jars in a large pot of simmering water to keep them hot.
   • Dishwasher: Run the sterilize cycle on your dishwasher, leaving the jars inside to stay hot.
   • Oven Method: Place washed jars on a baking sheet and heat them in the oven at 200°F to sterilize and keep them warm.

By keeping your jars hot, you’ll prevent any breakage when adding hot food and submerging them into boiling water for the canning process.

Lemon Juice or Citric Acid

To ensure safety, add bottled lemon juice or citric acid to each jar. This step is crucial to maintain the proper acidity level.

• Bottled lemon juice: 1 tablespoon per pint 2 tablespoon per quart.
• Citric Acid: ¼ tsp. per pint ½ teaspoon per quart.

Pack the Jars 

For whole prepared tomatoes, pack them tightly into the jars, pressing gently to release some of the tomato juice. For diced tomatoes, ladle them into the jars along with their juices. Leave a generous ½ inch of headspace at the top of each jar.

Optional Salt

If you like, add ½ teaspoon of canning salt per pint jar or 1 teaspoon per quart jar for flavor, I do not use salt in my tomatoes.

Cool the Jars

Once processing is complete, turn off the heat and wait 5 minutes. Then, carefully lift the jars out of the water using your jar lifter. Place them on a towel-lined surface, as they cool, you’ll hear the satisfying ping of the lids sealing. Resist the urge to check the jars or touch the jars too soon. 

Check the Seals

After 12-24 hours remove the screw bands, press on each lid to ensure they don't pop up and down. If it doesn’t pop back, the jar is sealed. If it does, refrigerate and use those tomatoes within a few days. Rinse off the jars and lids to remove any residue or hard water, date and lable each jar.

Cooling and Storing

Store your sealed jars in a cool, dark place, like a pantry or basement. Properly canned tomatoes can last up to 18 months according to most lid manufacturers. However, in my kitchen, if a jar is sealed it's good until I am ready to use it.

How Long Do Canned Tomatoes Last?

Properly canned tomatoes can last up to 12 to 18 months, according to the manufacturers of the lids, when stored in a cool, dark, and dry place. Over time, the quality may decline, with changes in texture, flavor, or color, but the tomatoes are typically safe to eat as long as the seals remain intact and there are no signs of spoilage, such as bulging lids, leaks, or an off smell. In my kitchen, my canned tomatoes are good for as long as I am willing to store them, provided they show no signs of failure or spoilage. For the best flavor and nutritional value, it’s still recommended to use your canned tomatoes within 18 months, but always inspect jars before use to ensure they’re safe for consumption. 

Stay Organized with the Canning and Preserving Journal

Take the stress out of food preservation with the Canning and Preserving Journal, a printable tool designed to simplify your canning process. This 16-page journal helps you track pantry inventory, schedule canning projects, and document recipes—all while ensuring safe practices. With features like a Year-Round Canning Guide, Pantry & Inventory Tracker, Recipe Cards, Monthly & Weekly Planners, and an Altitude Chart, this journal is perfect for beginners and seasoned canners alike. Stay organized, save time, and confidently preserve your harvest with this must-have resource for every home canner!

Best Tomatoes For Canning

When it comes to canning, choosing the right tomatoes is key for achieving the best flavor and consistency. Roma tomatoes and other paste tomatoes, such as San Marzano, are ideal for canning because they have fewer seeds, thicker flesh, and lower water content, which results in a richer sauce or paste. Fresh tomatoes from your garden can also be used, but varieties with a high water content, like beefsteak tomatoes, may require additional cooking to reduce excess liquid. For the best results, select firm, ripe tomatoes without blemishes to ensure your canned goods are flavorful and shelf-stable.