Canning whole tomatoes is one of the most useful ways to preserve a summer harvest. The finished jars work in soups, stews, sauces, and braises the same way store-bought whole peeled tomatoes do.
The process is straightforward, but it is not optional-free. Tomatoes sit near the acid/low-acid line, so every tested method requires added acid, peeled fruit, the correct packing liquid, and a process time matched to that pack. Skip those details and the jar may seal while still being unsafe.
This guide covers how to choose a packing method, prepare the fruit, fill jars, and process them using current USDA/National Center for Home Food Preservation directions.
Why Whole Tomatoes Must Be Acidified
Tomatoes were long treated as high-acid foods. Newer varieties, overripe fruit, and tomatoes from dead or frost-killed vines can have a pH above 4.6. Below that number, Clostridium botulinum cannot grow. Above it, the risk changes.
That is why official directions add acid to every jar of whole, halved, crushed, or juiced tomatoes, whether you use a boiling-water canner or a pressure canner. The pressure times published for these products are a shorter equivalent of the water-bath heat treatment. They are not a substitute for acid.
Add acid to the empty jar before filling so it is never forgotten:
| Jar size | Bottled lemon juice | Citric acid | 5% vinegar |
|---|---|---|---|
| Pint | 1 tablespoon | 1/4 teaspoon | 2 tablespoons |
| Quart | 2 tablespoons | 1/2 teaspoon | 4 tablespoons |
Use bottled lemon juice, not fresh. Fresh juice varies in acidity. Vinegar is allowed, but it changes flavor more than lemon juice or citric acid. A pinch of sugar can soften the tartness. Do not reduce the acid.
Do not can tomatoes from dead or frost-killed vines. Freeze or cook and eat those instead. Green tomatoes can be canned with the same recipes; they are usually more acidic than ripe fruit.
Choose the Pack Before You Start
Whole or halved tomatoes can be packed three tested ways. The pack you choose changes processing time more than almost anything else.
Packed in water Peeled tomatoes covered with boiling water (raw pack) or briefly simmered in water (hot pack). Best when you want the shortest water-bath time and do not mind a slightly diluted flavor. Water-bath time at 0–1,000 ft: 40 minutes for pints, 45 minutes for quarts.
Packed in tomato juice Same fruit, covered with hot tomato juice instead of water. Flavor is closer to commercial canned tomatoes. Water-bath time at 0–1,000 ft: 85 minutes for pints or quarts.
Packed raw with no added liquid Tomatoes are pressed into the jar until their own juice fills the gaps. No extra water or juice. Water-bath time at 0–1,000 ft: 85 minutes for pints or quarts.
If this is your first batch and you only have a large stockpot, pack in water. It is the least time-consuming water-bath option and still produces usable tomatoes.
Hot pack and raw pack are both approved for water-packed tomatoes. Hot pack usually gives a fuller jar, less floating, and less trapped air. Raw pack is faster on prep day and more likely to show floating fruit after processing. Floating is a quality issue, not a safety failure, if the jar sealed and was processed correctly.
What You Need
Produce Firm, ripe or slightly underripe tomatoes. Roma, San Marzano-type, and other paste tomatoes hold shape better than juicy slicing tomatoes, but any sound variety can be used the same way. Discard fruit with rot, large bruises, or mold. Cut away small blemishes.
Plan on about 3 pounds per quart, or 21 pounds for a canner load of 7 quarts and 13 pounds for 9 pints. A bushel (about 53 pounds) yields roughly 15 to 21 quarts.
Jars and lids Pint or quart canning jars in good condition. New two-piece lids. Rings can be reused if they are not bent or rusty.
Canner A boiling-water canner or any pot deep enough to cover jars with 1–2 inches of boiling water, plus a rack so jars do not sit on the pot bottom. Or a pressure canner (not a pressure cooker or multi-cooker unless the manufacturer and a tested recipe both say it is approved for canning).
Acid and optional salt Bottled lemon juice or citric acid. Salt is optional: 1/2 teaspoon per pint or 1 teaspoon per quart. It is for flavor only.
Do not add oil, butter, garlic, onion, celery, peppers, or fresh herbs to these jars. Those ingredients change acidity and density. They belong in tested salsa or sauce recipes, not in plain whole tomatoes processed as a water-bath product.
How to Peel Tomatoes for Canning
Tested times assume peeled tomatoes. Skins can interfere with heat penetration, add a tough texture, and carry a higher bacterial load. Leave skins on only if you are following a recipe that was specifically tested that way. Standard whole-tomato directions are not.
- Wash tomatoes under cool running water.
- Score a small X on the blossom end if you like; it is optional.
- Lower a few at a time into boiling water for 30 to 60 seconds, until the skins split.
- Move them immediately into cold water.
- Slip off the skins, cut out the cores, and trim any damaged spots.
- Leave whole or cut in half.
Work in batches so the fruit does not sit and soften.
Step-by-Step: Packing and Processing
Keep jars hot until they are filled. Keep lids ready according to the manufacturer’s directions. Fill one jar at a time.
1. Add acid (and salt, if using)
Put the measured lemon juice or citric acid in each hot jar first. Add salt only if you want it.
2. Pack the tomatoes
Water pack, raw: Fill the jar with peeled tomatoes, leaving 1/2-inch headspace. Cover with boiling water, still leaving 1/2-inch headspace.
Water pack, hot: Cover peeled tomatoes with water in a saucepan. Boil gently 5 minutes. Fill jars with hot tomatoes and cooking liquid, 1/2-inch headspace.
Juice pack: Use hot tomato juice in place of water, raw or hot (hot pack: simmer tomatoes in juice 5 minutes).
No added liquid: Press raw peeled tomatoes into the jar until juice fills the spaces. Leave 1/2-inch headspace. Do not add extra water.
3. Remove air bubbles
Slide a bubble tool or chopstick around the inside of the jar. Recheck headspace and add liquid if needed. Wipe the rim with a clean, damp cloth. Food on the rim is a common reason lids fail to seal.
4. Apply lids
Place a new lid on the rim. Screw the band on fingertip-tight. Do not crank it down. Over-tightening can cause buckling and siphoning.
5. Process for the time that matches your pack and altitude
Lower jars onto the canner rack. For a water bath, jars must stay covered by at least 1 inch of boiling water. Start timing only when the water returns to a full boil.
Stay at a steady boil for the full time. If the boil stops, bring it back and restart the clock.
Processing Times
Adjust for altitude. Water boils at a lower temperature as elevation rises, so time or pressure must increase.
Boiling-water canner
Whole or halved tomatoes packed in water (hot or raw)
| Jar size | 0–1,000 ft | 1,001–3,000 ft | 3,001–6,000 ft | Above 6,000 ft |
|---|---|---|---|---|
| Pints | 40 min | 45 min | 50 min | 55 min |
| Quarts | 45 min | 50 min | 55 min | 60 min |
Packed in tomato juice, or packed raw with no added liquid (hot or raw where allowed)
| Jar size | 0–1,000 ft | 1,001–3,000 ft | 3,001–6,000 ft | Above 6,000 ft |
|---|---|---|---|---|
| Pints or quarts | 85 min | 90 min | 95 min | 100 min |
Those two longer packs use the same water-bath clock. Do not use the 40/45-minute water-pack time for juice-packed or no-liquid jars.
Pressure canner
Acid is still required.
Water-packed whole or halved tomatoes (hot or raw), pints or quarts A common option: 10 minutes at 11 lb on a dial-gauge canner (0–2,000 ft) or 10 lb on a weighted-gauge canner (0–1,000 ft). Longer, lower-pressure options also exist in the official tables (15 minutes at 6 lb dial / 5 lb weighted at low elevation). Raise pressure at higher altitudes.
Juice-packed or no-added-liquid tomatoes need a longer pressure process than water-packed tomatoes (commonly 25 minutes at 11 lb dial / 10 lb weighted at low elevation, with other time/pressure combinations in the official tables). Match the table to the exact pack.
Vent the canner as the manufacturer directs before timing starts. Let pressure drop naturally. Do not rush the cool-down with cold water.
After the Canner Comes Off the Heat
Leave jars in the canner for 5 minutes after a water-bath process (heat off, lid off) before lifting them out. Sudden temperature change is a major cause of siphoning—liquid loss that leaves fruit exposed at the top of the jar.
Set jars upright on a towel. Do not tilt them. Do not retighten bands. Cool 12 to 24 hours.
Then check the seal: the lid should be concave and should not flex when pressed in the center. Remove the bands, wash the jars, label with the pack style and date, and store in a cool, dark, dry place.
If a jar did not seal: Within 24 hours you can refrigerate it, freeze the tomatoes, or reprocess in a clean jar with a new lid for the full original time. After 24 hours, do not reprocess.
Home-canned tomatoes are at their best within a year. Quality declines after that even when the seal holds.
Problems That Look Alarming but Often Are Not
Fruit floating at the top. Common with raw pack because raw tomatoes hold air. The jar can still be safe if it sealed and was processed correctly.
Clear liquid separated from solids. Normal. Stir after opening.
Some liquid lost during processing (siphoning). Usually caused by tight packing, wrong headspace, leftover air bubbles, over-tight bands, or pulling jars out too fast. If the seal is sound and there is no spoilage, keep the jar and use it sooner rather than later. Do not open a sealed jar to top it off.
White mineral film on jars or lids. Hard water. A splash of vinegar in the canner water can reduce it. It is not spoilage.
When to Throw the Jar Away
Discard without tasting if you see:
- A broken seal after storage
- Bulging lid
- Spurting liquid, fizzing, or rising bubbles when opened
- Mold
- Off odor
- Unusual sliminess
Botulism toxin does not always announce itself with obvious spoilage. When a jar’s history is uncertain—wrong process time, forgotten acid, added low-acid ingredients, or a recipe from an untested source—do not keep it. Official guidance for foods not canned to USDA recommendations is to treat them as unsafe.
How to Use Home-Canned Whole Tomatoes
Drain or keep the liquid depending on the recipe. Crush the tomatoes by hand for a rustic sauce, pulse them for a smoother one, or leave them whole in soups and braises.
Because these jars contain only tomatoes, acid, and optional salt, you can season them later. That is the point of canning them whole instead of as finished sauce.
If a batch tastes sharper than you like, a small amount of sugar or a pat of butter in the cooked dish will usually balance it. The extra acid in the jar is for safety, not for salad dressing tang.
Common Mistakes That Affect Safety
- Using a 40-minute water-bath time for juice-packed or no-liquid tomatoes
- Skipping lemon juice or citric acid because the tomatoes “taste acidic”
- Using fresh lemon juice
- Leaving skins on a recipe that was tested peeled
- Adding garlic, onion, oil, or meat to a plain tomato jar
- Canning overripe, rotten, or frost-killed fruit
- Ignoring altitude
- Treating a pressure cooker as a pressure canner
- Reusing flat lids
- Starting the process timer before the water is at a full boil
The most useful habit is matching three things every time: acid in the jar, peel on the counter, process time for that exact pack.
Frequently Asked Questions
Can I water-bath can whole tomatoes, or do I need a pressure canner? Either method is approved when the tomatoes are acidified and you use the time for your pack and altitude. Water bath is enough. Pressure canning is faster and often recommended for quality, not as a way to skip acid.
Do I have to peel them? Yes, for standard USDA whole-tomato directions. Processing times were developed with peeled fruit.
Can I leave the tomatoes raw? Yes, for water pack, juice pack, and the no-added-liquid method. Hot pack is also approved for water and juice packs and usually looks better in the jar.
Why is the no-liquid method processed so much longer than the water pack? Heat moves differently through a dense jar of pressed tomatoes than through tomatoes sitting in added water. The clock follows the pack, not the fruit variety.
Can I can cherry tomatoes whole? Small tomatoes can be packed whole if they are peeled and you follow a tested whole/halved method. Peeling cherries is tedious. Many people crush or freeze them instead.
Is floating a sign the jars are unsafe? No. Check the seal and look for real spoilage signs. Floating is usually trapped air.
How long do they last? Use within 12 months for best quality. Keep sealed jars in a cool, dark place. Refrigerate after opening and use within a few days.
What if I forgot the lemon juice? Do not store those jars on the shelf. Reprocess within 24 hours with the correct acid and a new lid, or refrigerate or freeze the tomatoes.
Canning whole tomatoes rewards careful prep more than special equipment. Choose firm fruit, add the measured acid, peel, match the process time to the liquid in the jar, and the pantry will hold a product you can cook from all winter.