Canning tomatoes for beginners comes down to three rules: use sound, ripe fruit; add bottled acid to every jar; and process the jars for the time that matches how you packed them. Do those three things and a water-bath canner is enough for plain whole, halved, crushed, or juiced tomatoes. Skip the acid, invent a recipe, or cut the processing time, and the jars are no longer a pantry project—they are a food-safety problem.
Tomatoes sit on the line between high-acid and low-acid foods. Variety, ripeness, growing conditions, and fruit from frost-killed vines can push pH above 4.6, the level where Clostridium botulinum can grow in a sealed jar. That is why current USDA and extension directions require acid in every jar, even if you use a pressure canner.
This guide starts with the batch most beginners should make first: hot-packed crushed tomatoes. They take less time than tomatoes packed with no added liquid, they float less, and they are the form most people actually cook with later.
What “safe” means for home-canned tomatoes
Botulism toxin is colorless, odorless, and tasteless. You cannot judge a jar by how it looks. Safety comes from a tested process, not from a tight lid.
A boiling-water bath reaches 212°F (100°C) at sea level. That temperature is enough for acidified tomatoes. It is not enough for plain vegetables, meat, or untested mixes of tomatoes plus low-acid ingredients such as onions, peppers, oil, or meat. Those need a pressure canner and a tested recipe of their own.
A pressure cooker or multi-cooker with a “canning” button is not a pressure canner. Do not use one for canning.
Add acid even when you pressure-can. The published pressure times for tomatoes were developed for acidified fruit, not for unacidified fruit. Leaving the acid out changes the process those times were built on.
What you need before you start
You do not need a specialty kitchen. You do need the right jars and a way to keep them covered with boiling water.
Equipment
- A boiling-water canner, or a deep stockpot with a rack so jars do not sit on the pot bottom
- Standard mason jars (pints or quarts) with no chips on the rim
- New two-piece lids; bands can be reused if they are clean and not bent
- Jar lifter, canning funnel, and a plastic bubble remover or spatula
- A second pot for peeling tomatoes
- Clean towels and a cooling space where jars will not be bumped for 12–24 hours
Ingredients
- Firm, ripe tomatoes free of cracks, rot, and insect damage
- Bottled lemon juice from concentrate, food-grade citric acid, or 5% acidity vinegar
- Optional: canning salt (not iodized table salt if you want a clear liquid) and a little sugar to soften the acid taste
Do not use fresh-squeezed lemon juice. Its acidity varies from lemon to lemon. Bottled juice is standardized.
How much acid goes in each jar
Add the acid to the empty jar first so you cannot forget a jar.
| Acid | Pint | Quart |
|---|---|---|
| Bottled lemon juice | 1 tablespoon | 2 tablespoons |
| Citric acid | ¼ teaspoon | ½ teaspoon |
| Vinegar, 5% acidity | 2 tablespoons | 4 tablespoons |
Vinegar is allowed, but it changes flavor more than lemon juice or citric acid. Sugar may be added to taste. Acid may not be reduced to taste.
Which tomatoes to can (and which to skip)
Paste types—Roma, San Marzano, Amish Paste, and similar plum tomatoes—give a thicker pack with less watery juice. Slicing tomatoes work, but they release more liquid and take more fruit per jar.
Use fruit that is ripe, firm, and harvested from living vines. Skip tomatoes that are:
- Rotten, moldy, or badly bruised
- Harvested from dead or frost-killed vines
- Overripe to the point of collapse
Those conditions raise the chance of a higher pH and of quality problems in the jar. Green tomatoes are more acidic than ripe ones and can be canned, but they are a different product with a sharper flavor.
How much fruit you need
- About 2½ to 3½ pounds of tomatoes fill one quart
- About 1¼ to 1¾ pounds fill one pint
- A canner load of 7 quarts takes about 21 pounds
- A canner load of 9 pints takes about 13 pounds
A kitchen scale helps. If you do not have one, three medium slicing tomatoes or about eight plum tomatoes is roughly a pound.
Choose the pack before you choose the timer
Processing time is not “however long tomatoes take.” It depends on pack style.
| Pack | What it is | Beginner notes | Water-bath time at 0–1,000 ft |
|---|---|---|---|
| Crushed, hot pack, no added liquid | Quartered tomatoes heated until juicy, then packed hot | Best first project; useful in sauces | Pints 35 min, quarts 45 min |
| Whole or halved, packed in water | Peeled tomatoes covered with hot water | Shortest whole-tomato time; slightly diluted | Pints 40 min, quarts 45 min |
| Whole or halved, packed in juice or with no added liquid | Tomatoes packed in their own juice | Fuller flavor; much longer process | Pints or quarts 85 min |
Those times are for elevations at or below 1,000 feet. Higher elevations need more time. Pressure-canner times are shorter but still require the same acid.
If this is your first day with a canner, make crushed tomatoes. The hot pack drives out air, reduces floating, and gives you a product you can turn into soup, chili, or sauce without extra work.
How to can crushed tomatoes in a water bath
This is a hot pack only. Do not raw-pack crushed tomatoes.
1. Heat the canner and wash the jars. Fill the canner about halfway with water and start heating it. Wash jars in hot soapy water. For a process longer than 10 minutes, the jars do not have to be sterilized in boiling water first, but they should be hot when filled so they do not crack.
2. Peel the tomatoes. Wash them. Cut a shallow X in the blossom end. Dip in boiling water 30 to 60 seconds, until the skin splits. Move to cold water. Slip off skins, cut out cores, and quarter the fruit. Cut away any green or damaged spots.
3. Crush and heat. Put about one-sixth of the quarters into a large pot. Crush them with a spoon or potato masher as they heat so they release juice and do not scorch. When they boil, add the remaining quarters. Stir often. Boil gently for 5 minutes.
4. Acidify the jars, then fill. Put the measured acid in each hot jar. Add ½ teaspoon salt per pint or 1 teaspoon per quart if you want it. Ladle in the hot crushed tomatoes, leaving ½-inch headspace.
5. Remove bubbles and lid the jars. Run a plastic spatula around the inside of the jar. Recheck headspace. Wipe the rim with a clean, damp cloth. Apply a new lid and screw the band on fingertip-tight—snug, not cranked down.
6. Process. Lower jars onto the rack. Water must cover the lids by 1 to 2 inches. Put the lid on the canner. When the water returns to a full rolling boil, start the timer:
- 0–1,000 ft: pints 35 minutes, quarts 45 minutes
- 1,001–3,000 ft: pints 40 minutes, quarts 50 minutes
- 3,001–6,000 ft: pints 45 minutes, quarts 55 minutes
- Above 6,000 ft: pints 50 minutes, quarts 60 minutes
Keep a steady boil the whole time. Add boiling water if the level drops.
7. Cool without touching the lids. Turn off the heat. Wait 5 minutes. Lift jars straight up and set them on a towel with space between them. Do not tilt. Do not retighten bands. Let them sit 12 to 24 hours.
8. Check the seal. Remove the bands. Press the center of each lid. It should be concave and not flex. If a jar did not seal, refrigerate it and use it within a few days, or reprocess within 24 hours with a new lid and the full processing time.
Label the sealed jars with the contents and date. Store them in a cool, dark, dry place. Peak quality is about 12 to 18 months.
If you want whole or halved tomatoes instead
Peel as above. Leave the tomatoes whole or cut them in half.
Packed in water (shorter process): Add acid to the jar. Pack tomatoes, leaving ½-inch headspace. Cover with boiling water, still leaving ½-inch headspace. Remove bubbles. Process pints 40 minutes and quarts 45 minutes at 0–1,000 feet (add 5 minutes per elevation band as in the crushed-tomato table). Hot pack or raw pack uses the same time for this style.
Packed in juice or with no added liquid (longer process): This pack tastes more like tomato and less like water, but water-bath time jumps to 85 minutes for pints and quarts at 0–1,000 feet. A pressure canner shortens that to 25 minutes at the correct pressure for your gauge and altitude—still with acid in every jar.
Hot packing whole tomatoes (simmer 5 minutes in water or juice before filling) usually gives a better-looking jar than raw packing.
Water bath or pressure canner?
For plain acidified tomatoes, both methods are approved. The choice is practical.
Water bath is the better first tool. The pot is cheaper, the process is easier to watch, and you can see that the water stays at a boil. The tradeoff is a longer boil and, for some packs, more heat damage to texture.
Pressure canning usually gives a firmer, brighter product and a shorter clock. It also requires a true pressure canner, a working gauge, and altitude-adjusted pounds of pressure. Dial gauges should be checked yearly.
If you already own a pressure canner and know how to vent it and hold pressure, use the tested tomato tables that came with current USDA or NCHFP directions. Do not borrow times from a different pack style.
After the jars cool: what is normal and what is not
These things look alarming and are usually only quality issues if the jar sealed and there is no mold or off odor:
- Tomatoes floating above a layer of liquid
- Separation of juice and pulp
- A little liquid loss during processing
- Fine sediment on the bottom
Floating is common with raw packs because raw fruit holds air. Hot packing, firm fruit, tight (not crushed) packing, and bubble removal reduce it. It does not make a sealed jar unsafe.
Discard without tasting if:
- The lid never sealed, or the seal later failed
- The jar is bulging, leaking, or spurts when opened
- You see mold
- The food smells wrong
When in doubt, throw it out where people and pets cannot eat it. Do not taste-test a suspect jar.
As extra insurance, many public-health sources still advise boiling home-canned tomatoes for 10 minutes before eating (add 1 minute per 1,000 feet above 1,000 feet). That step does not replace correct canning. It is a backup after the jar is opened.
Mistakes that make a first batch fail
Skipping the acid “because these tomatoes are acidic enough.” You cannot measure pH by taste, variety name, or an heirloom label. Add the listed amount every time.
Using a family salsa recipe in a water bath. Onions, peppers, and garlic lower acidity. Only tested salsa formulas belong in a canner. A fresh pico recipe is for the refrigerator.
Adding oil, butter, or meat to “make sauce in the jar.” Fat can interfere with heat penetration and with the lid seal. Meat turns the product into a low-acid food that needs a pressure process written for that recipe.
Canning in the oven, dishwasher, or an open kettle. Those methods are not approved and do not replace a boiling-water or pressure process.
Starting the timer before the water is fully boiling again. The clock starts when the canner returns to a rolling boil with the jars in it, not when the jars first go in.
Over-tightening bands. Air has to leave the jar during processing. Fingertip-tight is enough. Cranking the band can cause buckling lids and failed seals.
Ignoring altitude. Water boils at a lower temperature as elevation rises. If you live above 1,000 feet, use the longer time. Guessing “close enough” under-processes the food.
Using damaged fruit to “save” a harvest. Canning concentrates problems. Bruised or rotting tomatoes belong in the compost, not in a sealed jar.
What this method does not cover
Plain canned tomatoes are a building block. They are not the same as:
- Spaghetti sauce with vegetables or meat
- Salsa
- Creamy tomato soup
- Tomato products with added oil
Those have their own tested recipes and, often, pressure-canning requirements. If you want sauce, can the tomatoes plain now and season them when you open the jar. That is the safest beginner path and usually the best-tasting one.
Freezing is a legitimate alternative. Frozen tomatoes do not need added acid. They take less equipment and more freezer space. If you have more fruit than time, freeze some and can the rest.
Frequently asked questions
Do I have to peel tomatoes? For these tested whole, halved, and crushed directions, yes. Skins can harbor organisms and affect texture. The boil-and-ice-water method is faster than peeling raw fruit.
Can I leave the skins on if I blend them later? Not in these processes. Use a tested recipe written for unpeeled product, or peel first.
Is citric acid better than lemon juice? Both are approved. Citric acid usually changes flavor less. Lemon juice is easier to find. Measure either one; do not swap volumes.
Why did my tomatoes separate into juice and pulp? An enzyme in raw tomatoes can cause that layering. Heating the fruit before packing slows it. Separation is ugly, not a safety test by itself.
Can I reuse commercial pasta-sauce jars? No. Use jars made for home canning. One-use commercial jars and lids are not built for repeated boiling-water or pressure processing.
How do I use the finished jars? Drain or keep the liquid as needed. Use crushed tomatoes anywhere you would use a can of tomatoes from the store: simmered sauce, soup, chili, shakshuka, braises. If the acid taste is sharp, a pinch of sugar in the pot usually balances it.
What if I only have a few pounds of tomatoes? Can pints. A small batch is still worth doing if the fruit is good. Do not scale a tested salsa or sauce recipe by guesswork; for plain tomatoes, pint and quart directions already exist.
Canning tomatoes for beginners is not a personality test and it is not a folk craft you “just feel.” It is a short list of measured steps. Acid in the jar, the right pack, the full boil, and an undisturbed cool-down will give you shelves of tomatoes that are actually safe to open in January.