Preserve · field guide
How to Can Tomato Sauce: Safe Water-Bath Recipe (2026)
A row of paste tomatoes gives more fruit than any family can eat fresh, and sauce is the best way to save it. Paste tomatoes run about 10 lb per plant, so a few plants make gallons of sauce. The work is mostly waiting for the pot to cook down. The one step you cannot skip is adding acid before you can it. Here is why, the exact times, and how to fix a watery batch.
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Read this first: tomatoes need added acid
Tomatoes sit right on the edge of the pH that is safe for water-bath canning. To can them safely you must add acid to every jar, every time. This is not optional and it is not a place to guess.
Add 2 tablespoons of bottled lemon juice per quart jar (1 tablespoon per pint). Use bottled, not fresh, because bottled has a steady acidity you can trust. If you would rather not add acid, use a pressure canner instead, which is the other safe path. These amounts and times follow the tested USDA and National Center for Home Food Preservation guidelines.
Start with paste tomatoes
Paste varieties have more flesh and less water, so they cook down faster into a thick sauce. A paste tomato runs about 80 days from transplant and yields roughly 10 lb per plant.
It takes about 3 lb of tomatoes to fill each quart of sauce after the water cooks off. So plan on roughly 21 lb for a 7-quart batch. Slicing tomatoes work too, they just take longer to thicken.
Cook it down and mill it
Wash, core, and quarter the tomatoes, then simmer them soft. Run the soft tomatoes through a food mill to strip out skins and seeds in one pass. A mill saves the slow job of peeling and coring by hand, and it is the tool that makes a big batch doable in an afternoon.
After milling, simmer the sauce until it thickens to the body you want. Expect it to reduce by about half, which can take 1 to 2 hours over low heat. Do not add cornstarch or flour to thicken a batch you plan to can; thickeners are not safe in home-canned tomato products. Reduce it by simmering instead.
Acidify, jar, and process
Add 2 tablespoons of bottled lemon juice to each empty quart jar first, then ladle in the hot sauce, leaving 1/2 inch of headspace. Wipe the rims, set the lids finger-tight, and lower the jars into the canner. Start the clock only once the water returns to a full, rolling boil.
| Jar size | At 0–1,000 ft | Lemon juice |
|---|---|---|
| Quarts | 40 min | 2 tbsp per jar |
| Pints | 35 min | 1 tbsp per jar |
Adjust the time for your altitude
Water boils cooler the higher you live, so higher elevations need extra minutes to reach a safe kill. Find your elevation and add these minutes to the base time above:
| Your elevation | Add to the time |
|---|---|
| 0–1,000 ft | none (use the base time) |
| 1,001–3,000 ft | +5 min |
| 3,001–6,000 ft | +10 min |
| 6,001–8,000 ft | +15 min |
| 8,001–10,000 ft | +20 min |
Fix a watery or separated sauce
The most common complaint is thin sauce, and it is always the same fix: more simmering.
- Watery sauce: it did not reduce enough. Any sauce should cook down by about half until it coats a spoon. Paste tomatoes thicken faster than slicing types.
- Layers separating in the jar: harmless. The clear layer on top is water that will stir back in. To reduce it, cook and jar the sauce hot and fast rather than letting it sit before canning.
- No food mill: quarter the cooked tomatoes and press them through a fine sieve or colander, or blend and simmer longer to thicken. Our no-mill method walks it through.
Store it right
Let the jars sit undisturbed for 12 to 24 hours, then press each lid: a sealed lid does not flex. Sealed jars keep their best quality for about 12 to 18 months in a cool, dark pantry.
Label every jar with the date and eat the oldest first. Any jar that did not seal goes in the fridge and gets used within a week.
Recipe
Ingredients
- About 21 lbs ripe paste tomatoes
- Bottled lemon juice (2 tbsp per quart jar, 1 tbsp per pint)
- Canning salt (optional, 1 tsp per quart)
Method
- Wash jars and keep them hot. Heat water in the water-bath canner.
- Wash, core, and quarter the tomatoes, then simmer until soft.
- Run the soft tomatoes through a food mill to remove skins and seeds.
- Simmer the sauce until it reduces by about half and thickens, 1 to 2 hours.
- Add 2 tbsp bottled lemon juice to each quart jar (1 tbsp per pint), then ladle in hot sauce, leaving 1/2 inch headspace.
- Wipe rims, set lids finger-tight, and process quarts 40 minutes (pints 35) at a full boil, adding time for your altitude.
- Cool 12 to 24 hours and check seals.
Keep going
Questions, answered straight
Yes. Tomatoes are borderline-acid, so a water-bath canner is only safe if you add 2 tablespoons of bottled lemon juice per quart (1 per pint). Skipping it risks botulism, which you cannot see, smell, or taste.
Plain acidified tomato sauce processes 40 minutes for quarts and 35 minutes for pints, timed from a full rolling boil at 0 to 1,000 feet. Add 5 to 20 minutes for higher elevations using the chart above.
Yes. A pressure canner reaches a higher temperature, so it is the other safe way to can tomato sauce. But most home canners find the water-bath-plus-lemon-juice method simpler and cheaper.
About 3 lb of paste tomatoes per quart after the sauce cooks down. For a full 7-quart canner load, plan on roughly 21 lb.
It needs more simmering. Paste tomatoes thicken faster than slicing types, but any sauce should reduce by about half. Keep it on low heat for 1 to 2 hours until it coats a spoon. Never thicken canning sauce with flour or cornstarch.
No. Those are low-acid and change the pH, so a sauce with added vegetables or meat must be pressure canned. Keep water-bath sauce to tomatoes plus the measured acid, and add aromatics when you cook with it.
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