Canning stewed tomatoes is not the same job as canning plain tomatoes. Once onion, pepper, or celery goes into the pot, the mixture is a tomato-vegetable product. That change matters for safety: tested extension recipes process this mix in a pressure canner, not a boiling-water bath.
The jars are useful. One quart becomes soup, chili, braised chicken, or a weeknight pasta sauce without opening several cans. The work is straightforward if you follow a tested recipe, keep the vegetable amounts small, and adjust pressure for altitude. Skip those limits, and the extra low-acid vegetables can leave the jar in the danger zone for Clostridium botulinum.
This guide covers the tested recipe used by Cooperative Extension programs, how to decide between pressure canning and a water-bath alternative, and the mistakes that show up most often in home kitchens.
What “stewed tomatoes” means in a canning recipe
In cooking, stewed tomatoes can mean almost anything simmered until soft. In home canning, the phrase usually means peeled, chopped tomatoes cooked briefly with a small, measured amount of onion and green pepper (sometimes celery salt for flavor).
That distinction is the whole safety question:
| What you want in the jar | Safe method | Why |
|---|---|---|
| Plain crushed or chopped tomatoes only | Water bath or pressure, after adding acid | Acidified tomatoes can be treated as a high-acid food. |
| Tomatoes plus the small vegetable amounts in a tested stewed-tomato recipe | Pressure canner only | Added onion and pepper lower acidity. The tested process uses pressure, not a water bath. |
| A loaded mix with extra celery, garlic, oil, meat, or large amounts of vegetables | Do not invent a process | Unmeasured low-acid additions change heat penetration and pH. Freeze the extra, or use a different tested recipe. |
If you only have a water-bath canner, can acidified crushed tomatoes and add onion and pepper later when you cook. That is safer than stretching an untested “water-bath stewed tomatoes” recipe.
Why extra vegetables change the process
Tomatoes sit near pH 4.6, the line between high-acid and low-acid food. Variety, ripeness, and vine health can push them above that line. USDA and university researchers therefore treat home-canned tomatoes as needing added acid when they are packed whole, crushed, or juiced.
Onion, pepper, and celery are low-acid foods. Mixing them into tomatoes can raise pH and slow heat movement through the jar. A boiling-water bath reaches 212°F (100°C) at sea level. That is enough for properly acidified high-acid foods. It is not the control used for low-acid vegetables. A pressure canner reaches about 240°F at 10–11 pounds of pressure, which is the temperature used to destroy botulism spores in low-acid foods.
That is why Extension publications list stewed tomatoes under pressure canning, even though plain crushed tomatoes may be water-bathed after acidification.
Do not assume “I added lemon juice, so water bath is fine” unless you are following a specific university-tested recipe written for that method and those exact ingredient amounts.
Choose tomatoes that can safely
Use firm, ripe, disease-free fruit from healthy vines. Do not can tomatoes from dead or frost-killed vines. Those fruits carry a higher microbial load and can have weaker acidity.
Paste types (Roma, San Marzano, Amish Paste) give a thicker pack with less watery juice. Slicing tomatoes work, but the finished jars will be looser. Green tomatoes are more acidic than ripe fruit and may be included, but they change flavor and texture.
Avoid:
- Soft, overripe, or moldy fruit
- Large bruised sections (trim small spots; discard bad fruit)
- Adding oil to the jars (oil can interfere with seals and is not part of tested tomato processes)
Yield guide: The small tested batch below starts with 2 quarts of chopped peeled tomatoes and fills about 3 pint jars. A doubled batch (4 quarts chopped tomatoes) fills about 6 pints or 3 quarts. Plan roughly 2½ to 3 pounds of whole tomatoes per quart of finished product, depending on juiciness.
Equipment you actually need
- Pressure canner with a working dial or weighted gauge (have dial gauges checked yearly)
- Canning jars, new lids, and bands
- Jar lifter, funnel, headspace tool or clean ruler
- Large stainless steel or enameled pot (avoid reactive aluminum for long tomato cooks)
- Slotted spoon and bubble remover
- Bottled lemon juice or food-grade citric acid if you acidify jars (see note below)
A pressure cooker is not automatically a pressure canner. Use a canner large enough to hold jars on a rack, vent steam for 10 minutes, and hold steady pressure for the full process time.
Tested stewed tomatoes recipe
This is the recipe published by Cooperative Extension sources based on So Easy to Preserve / USDA tomato-product guidance. Keep the vegetable amounts as written. Do not double the onion or pepper “because it tastes better” if you still plan to can the mix.
Small batch (about 3 pint jars)
- 2 quarts peeled, cored, chopped tomatoes
- ¼ cup chopped green peppers
- ¼ cup chopped onions
- 2 teaspoons celery salt
- 2 teaspoons sugar
- ¼ teaspoon salt
Doubled batch (about 6 pints or 3 quarts)
- 4 quarts peeled, cored, chopped tomatoes
- ½ cup chopped green peppers
- ½ cup chopped onions
- 4 teaspoons celery salt
- 4 teaspoons sugar
- ½ teaspoon salt
Salt and sugar are for flavor. You may leave them out. Do not leave out the vegetables and then treat this as a different product without checking the matching tomato recipe. Do not add extra vegetables, garlic cloves by the handful, or oil.
Acid note: USDA recommends adding bottled lemon juice or citric acid to whole, crushed, and juiced tomatoes. Many published stewed-tomato processes rely on pressure rather than listing lemon juice in the ingredient list. Adding the standard tomato acidification amounts does not hurt safety and is a reasonable extra step if you want it: 1 tablespoon bottled lemon juice or ¼ teaspoon citric acid per pint; 2 tablespoons lemon juice or ½ teaspoon citric acid per quart. Use bottled juice, not fresh-squeezed, because bottled acidity is consistent.
Vinegar (5% acidity) can replace lemon juice at 2 tablespoons per pint or 4 tablespoons per quart, but the flavor is sharper.
Step-by-step method
1. Prepare jars and canner
Wash jars, lids, and bands. Keep jars hot. Put the rack and 2 to 3 inches of water in the pressure canner and begin heating so the canner is hot when jars are filled. Follow your canner manual for water depth.
2. Peel the tomatoes
Score a small X on the blossom end if you like. Dip tomatoes in boiling water 30 to 60 seconds, until skins split. Move them to cold water. Slip off skins, remove cores, and cut away any damaged flesh. Chop.
Peeling is part of tested tomato procedures. Skins can affect heat penetration and leave tough bits in the jar.
3. Cook the mixture
Combine tomatoes, pepper, onion, celery salt, sugar, and salt in a large pot. Cover and cook 10 minutes, stirring often so the bottom does not scorch. The tomatoes should be hot and beginning to soften, not cooked down into paste.
4. Fill the jars
If you are adding lemon juice or citric acid, put it in the empty hot jars first. Ladle the hot mixture into jars, leaving ½-inch headspace. Release trapped air bubbles and add more mixture if the level drops. Wipe rims clean. Apply lids and bands fingertip-tight.
Do not pack jars so full that liquid cannot circulate. Overfilling is a common reason for siphoning and failed seals.
5. Process in a pressure canner
Load jars on the rack. Lock the lid. Vent steam in a steady stream for 10 minutes, then close the vent or add the weight. Bring the canner to the correct pressure for your gauge type and altitude. Start the timer only after pressure is reached.
Processing time (do not shorten):
- Pints: 15 minutes
- Quarts: 20 minutes
Pressure at altitude:
Dial-gauge canner
| Altitude | Pressure |
|---|---|
| 0–2,000 ft | 11 lb |
| 2,001–4,000 ft | 12 lb |
| 4,001–6,000 ft | 13 lb |
| 6,001–8,000 ft | 14 lb |
Weighted-gauge canner
| Altitude | Pressure |
|---|---|
| 0–1,000 ft | 10 lb |
| Above 1,000 ft | 15 lb |
These times and pressures match Extension publications of the stewed tomatoes recipe.
When the time is up, turn off the heat and let the canner depressurize on its own. Do not force-cool it. After the gauge returns to zero and the lock drops, wait the extra minutes your manual specifies (often 10 minutes), then open the lid away from you. Remove jars and cool 12 to 24 hours without tightening bands.
6. Check seals and store
A sealed lid does not flex in the center. Remove bands, wash jars, label with contents and date, and store in a cool, dark place. Best quality is usually within 12 to 18 months.
Unsealed jars can be refrigerated and used within a few days, or reprocessed within 24 hours with a new lid if the food is still sound.
If you do not have a pressure canner
Do not water-bath the vegetable-added recipe above. Use one of these instead:
Can plain crushed tomatoes. Peel, crush, and hot-pack tomatoes with no added onion or pepper. Add bottled lemon juice or citric acid to each jar. Process in a boiling-water canner: pints 35 minutes and quarts 45 minutes at 0–1,000 feet, adding time for altitude. That product is the closest pantry substitute. You can sauté onion and pepper when you open the jar.
Freeze stewed tomatoes. Peel, quarter, and cook tomatoes 10 to 20 minutes until tender. Cool the pot in cold water, pack into freezer containers with headspace, and freeze. Frozen tomatoes do not need added acid. Texture will be soft after thawing, which is fine for soup and sauce.
Use a different tested mix. Some university “tomato-vegetable juice” or salsa recipes are written for water-bath canning because they control vegetable ratios and add a measured amount of vinegar or lemon juice. Those are separate recipes. Do not borrow their times for a homemade stew.
How to use a jar after you open it
Home-canned stewed tomatoes are already cooked. Drain some juice for a thicker skillet sauce, or use the whole jar.
Good uses:
- Simmer with browned ground meat and Italian seasoning for a fast pasta sauce
- Build vegetable soup or minestrone
- Braise chicken thighs or pork
- Make chili or stuffed-pepper filling
- Spoon over rice with beans
Before tasting any home-canned tomato product that was pressure-canned incorrectly, or any jar with a questionable seal, follow USDA guidance: if you are unsure about a low-acid or tomato product, boil it for 10 minutes at elevations below 1,000 feet, adding 1 minute per additional 1,000 feet. When in doubt, throw it out. Botulism toxin is not something you can see or smell reliably.
Discard jars with bulging lids, spurting liquid, off odors, mold, or unusual cloudiness.
Mistakes that make jars unsafe or poor quality
Treating blog recipes as equivalent to USDA processes. Many popular posts water-bath stewed tomatoes with extra celery, garlic, and oil. That is not the tested Extension recipe. Extra low-acid food changes the product.
Doubling the vegetables. A quarter cup of onion and pepper per 2 quarts of tomatoes is part of the tested formula. A skillet’s worth of soffritto is not.
Skipping altitude adjustments. At higher elevations, water boils cooler and weighted gauges need 15 pounds. Using sea-level pressure at 4,000 feet under-processes the food.
Using fresh lemon juice. Acidity varies by fruit. Bottled juice is standardized.
Confusing citric acid with ascorbic acid. Ascorbic acid (vitamin C) helps color. It does not replace citric acid for pH control.
Raw-packing this recipe. The tested stewed tomatoes process is a hot pack after a 10-minute cook. Raw pack times for other tomato styles do not transfer.
Leaving skins on “for nutrition.” Tested processes were developed with peeled tomatoes. Skins can also taste bitter and curl into tough strips.
Open-kettle canning (cooking the food, pouring it into jars, and skipping a canner). USDA does not recommend it.
Quality details that are optional, not safety rules
- Sugar offsets tartness from lemon juice; it is not a preservative here.
- Herbs such as dried basil or oregano appear in some manufacturer recipes (for example, Bernardin’s Italian stewed tomatoes), which are still pressure-canned. Do not add fresh herbs or extra vegetables to the Extension recipe and keep the same time.
- You can use celery instead of some pepper only if a tested recipe says so. Do not freelance substitutions of large vegetable volumes.
- Roma tomatoes make a thicker jar; beefsteaks make a juicier one. Both are fine if sound and ripe.
Frequently asked questions
Can I water-bath stewed tomatoes if I add extra lemon juice?
Not for the vegetable-added Extension recipe. Extra acid is not a free pass to ignore a pressure process written for a tomato-vegetable mix. If you want water-bath canning, use acidified crushed tomatoes with no added low-acid vegetables, or a different recipe that a university actually tested for boiling-water processing.
Do I have to peel the tomatoes?
Yes for this process. Tested tomato canning procedures assume peeled fruit. Peeling also improves texture.
Can I use cherry tomatoes?
Yes if they are sound and ripe. They take longer to peel. The chopped measure still has to match the recipe. Expect more skins and a looser pack if you skip peeling, which you should not do for this method.
Can I add garlic, mushrooms, zucchini, or meat?
Not in this recipe. Those are low-acid additions and belong in other tested products (some tomato-okra recipes, tested spaghetti sauces with measured vegetables, or meat sauces with their own pressure times). Freeze custom mixtures.
Why do some jars lose liquid?
Siphoning happens when pressure fluctuates, jars are overfilled, bubbles are left in the pack, or the canner is cooled too fast. The food can still be safe if the lid sealed and the jar was processed correctly. Use remaining jars first if the headspace looks high.
How long do sealed jars last?
Store 12 to 18 months for best quality. Sealed, properly processed jars kept cool and dark remain a safety question of process, not of a calendar date alone. Quality fades: color darkens, texture softens.
What if my family prefers a sweeter, more “store-bought” flavor?
Add a little sugar in the pot, or add sugar when you cook from the jar. Do not reduce lemon juice or citric acid to make the product milder.
A simple way to decide before you start
Ask one question: Are onion, pepper, celery, or other vegetables going into the jar?
- No, only tomatoes (plus salt and required acid): you may water-bath or pressure-can using a crushed or whole-tomato process.
- Yes, in the small amounts from the tested stewed recipe: pressure-can 15 minutes for pints, 20 minutes for quarts, with altitude-adjusted pressure.
- Yes, in larger or different amounts: do not can that mixture unless you have a tested recipe for that exact product. Freeze it.
That single decision is more useful than collecting extra recipes. The tested stewed tomatoes formula is small on purpose. It gives you a flexible pantry ingredient without turning the jar into an untested stew.