How to Can Basic Smooth Tomato Sauce

If you’re new to canning tomato sauce, here are a few things to keep in mind before you get started. Roma tomatoes work best thanks to their low moisture and meaty texture, but any variety will do in a pinch. Don’t skip the bottled lemon juice. It’s what keeps this recipe safe for water bath canning.

And think about how you’ll use your sauce before you prep your jars: pints are great for family meals, but half-pints might be better for single servings or quick recipes.

Ingredients and Tools You’ll Need

Ingredients

• 7 pounds Roma tomatoes (meaty and low in water; ideal for thick sauce)
• 3 tablespoons bottled lemon juice (do not use fresh; bottled ensures safe acidity)
• 2 teaspoons canning salt, optional (can be omitted or replaced with citric acid)

Tools

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• Clean cloth (for wiping jar rims before sealing)
• Cutting board and knife
• Large stock pot (for simmering the tomatoes and reducing the sauce)
• Food mill (removes skins and seeds for a smooth texture)
• Water bath canner (or large stockpot with rack)
• Pint or half-pint jars with lids and rings (half-pints are great for small servings)
• Jar lifter, canning funnel, ladle (basic tools for safe and clean filling)

How to Make Canned Tomato Sauce

Honestly, reading all the steps is more overwhelming than actually making the recipe. We’re just processing here, not exactly cooking a recipe. Then we’re putting everything into jars and boiling to seal it. Easy, right? Right. Let’s do this.

Step One: Wash and Chop Your Tomatoes

Start by giving your tomatoes a good rinse to remove any dirt or residue. Then quarter them—no need to peel or core yet. You’re just breaking them down enough so they’ll simmer evenly and fit in the pot. Use a large stockpot because the volume adds up quickly once you start.

Roma tomatoes are my favorite canning tomato because they’re meatier and cook down into a nice, thick sauce without too much water. If you’re using another variety, expect a longer reduction time.

Step Two: Simmer to Soften

Transfer the tomatoes to your pot and set it over medium heat. Stir frequently as they heat up. Tomatoes can burn fast if left alone at the bottom of the pot. Once the mixture is bubbling, reduce the heat slightly and simmer for about 10 minutes. This softens them just enough to move through the food mill easily.

Don’t worry about the skins and seeds, those come out in the next step. One of the wonders of a food mill!

Step Three: Run Through the Food Mill

Working in batches, ladle the softened tomatoes into your food mill set over a large bowl. Crank it until you’re left with nothing but seeds and skin in the mill and smooth juice in the bowl.

If you don’t have a food mill, you can use a blender, but you’ll end up with seeds and skins in the final product. The flavor’s still good but it won’t be as smooth.

Step Four: Simmer and Reduce

Pour the strained juice back into your (cleaned) stockpot and bring it to a simmer again. This is where you decide what kind of sauce you want: thicker or thinner.

• For a thinner sauce, simmer about 1 hour. (This will most closely mimic store bought plain canned tomato sauce and is what I typically do)
• For a thicker, richer sauce, aim for 90 minutes or more. (This would be closer to a sauce that you’d season and serve over pasta.)

Stir often to prevent scorching, especially as the liquid cooks down. You’ll notice the color deepen and the texture slowly thicken.

Don’t cover the pot! You want that moisture to cook off. Just give it a good stir every 10–15 minutes.

Step Five: Prep Your Jars

While the sauce is reducing, get your jars ready. Wash them with hot soapy water, then place them in your canner filled with water and bring it to a low simmer. This keeps them hot and prevents breakage when you fill them with hot sauce.

No need to sterilize your jars if you’re water bath canning for the full time, the heat will do the job. But they do need to be hot and (obviously!) clean.

Place lids and rings in a bowl of warm (not boiling) water or just set them aside clean and dry. Preheating is optional with modern lids.

Step Six: Fill the Jars

Once the sauce is as thick as you like, pull your jars out of the canner and set them on a towel.

Add 1 tablespoon bottled lemon juice to each pint jar (or 2 tablespoons for quarts, ½ tablespoon for half-pints). Then ladle in the hot sauce, leaving ½ inch of headspace.

Use a canning funnel if you have one, it makes this part so much easier and less messy.

Debubble with a chopstick or debubbler, wipe the rims with a clean, damp cloth, and screw on the lids fingertip tight.

Step Seven: Process in the Water Bath

Carefully transfer the filled jars back into the canner, making sure they’re covered by at least 1 inch of water. Bring the water to a full, rolling boil, then start your timer: 35 minutes for pints, 40 minutes for quarts.

Once the time is up, turn off the heat but don’t move the jars yet, let them rest in the water for 5 minutes.

Step Eight: Cool and Store

Lift the jars out and place them on a towel or cooling rack, spaced apart and out of drafts. Don’t touch them for at least 12 hours.

As they cool, you’ll hear the telltale pop of the seals forming. After 12–24 hours, check each jar. Just press on the center of the lid to make sure it doesn’t flex. If sealed, label and store in a cool, dark place for up to 18 months.

Any jars that didn’t seal should go into the fridge and be used within a few days.

More Ways to Preserve Tomatoes

You’ll never regret having all the tomato basics in your pantry!

• Diced tomatoes are perfect in soups and sauces
• Whole tomatoes are great for heartier, slow cooked recipes
• If you don’t mind lots of simmering time, you can make your own canned tomato paste.
• But my favorite way is crushed tomatoes for the base of so many recipes.

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