Grape tomatoes can be preserved, but packing them whole in canning jars is not a tested home-canning method. University Extension publications advise against canning whole cherry or grape tomatoes because USDA process times were developed for larger peeled tomatoes, not these small fruits. The only canning path that stays inside tested guidance is to peel them, crush or juice them, add a measured acid, and process for that product. For most households sitting on a late-summer glut, freezing or drying is the better use of the fruit.
Can you can grape tomatoes?
Not whole. Ohio State University Extension states that canning whole cherry or grape tomatoes is not advised. Illinois Extension is equally direct: cherry and grape tomatoes are not recommended for canning.
The reason is narrower than “small tomatoes are unsafe.” The USDA Complete Guide to Home Canning and the National Center for Home Food Preservation (NCHFP) publish tested processes for crushed tomatoes, tomato juice, tomato sauce, and whole or halved tomatoes. Those processes were not developed or validated for cherry or grape tomatoes packed whole. Elizabeth Andress, then director of the NCHFP, told Ohio State Extension that the needed tests simply had not been done, and neither she nor OSU specialists recommended canning whole cherry tomatoes.
That leaves two honest options. Use grape tomatoes only in a product form that matches a tested recipe — peeled, crushed, juiced, or sauced, then acidified and processed for that form. Or skip canning and freeze or dry them, which is what current Extension guidance favors for this size of fruit.
Why a whole pack is the wrong fit
Tested canning times assume a known jar fill, a known piece size, and peeled fruit. Heat has to reach the coldest spot in the jar and stay there long enough to control spoilage organisms. Grape tomatoes break those assumptions in a few practical ways.
They are small, oblong, and firm, with a higher skin-to-flesh ratio than a slicing or paste tomato. Packed whole, they leave irregular air pockets. Skins, if left on, can slow heat movement in ways the original tests did not measure. Peeling them one by one is possible — a short dip in boiling water splits the thin skins — but a jar of peeled whole grape tomatoes is still not the product that was tested.
Blog recipes that raw-pack unpeeled grape tomatoes and borrow a “whole tomatoes in water” time are improvising. Acidification and a long boil do not automatically make an untested pack safe. Process time and preparation have to match.
Why tomatoes need added acid
Tomatoes sit on the border between high-acid and low-acid foods. Clostridium botulinum, the bacterium that produces botulinum toxin, cannot grow at a pH of 4.6 or lower. Many tomatoes fall at or below that line. Some modern varieties, overripe fruit, and tomatoes from dead or frost-killed vines can sit above it.
Because home canners cannot measure the pH of each batch, USDA and university researchers require added acid for whole, crushed, or juiced tomatoes. Acid is required for boiling-water canning and for pressure canning. Pressure does not replace the acid in these tomato products.
Add one of these to each jar before filling:
| Acid | Per pint | Per quart |
|---|---|---|
| Bottled lemon juice | 1 tablespoon | 2 tablespoons |
| Citric acid | 1/4 teaspoon | 1/2 teaspoon |
| Vinegar, 5% acidity | 2 tablespoons | 4 tablespoons |
Use bottled lemon juice, not fresh-squeezed. Bottled juice has a standardized acidity; fruit from a single lemon does not. Citric acid is the white crystalline powder sold for canning. It is not ascorbic acid, which preserves color and does not acidify the jar. Vinegar at 5% acidity is allowed in these amounts, but it changes the flavor more than lemon juice or citric acid. A small amount of sugar may be added for taste. It does not replace the acid, and the acid amount cannot be reduced.
Do not can tomatoes from dead or frost-killed vines. Skip fruit that is overripe, decayed, or badly cracked. Firm, disease-free, ripe or slightly under-ripe fruit is the starting point for any tomato product that will be canned.
If you can them, match a tested crushed or juice process
Older Extension guidance allowed cherry and grape tomatoes in sauce and juice when the fruit was prepared and processed exactly like the tested product. That is a narrower permission than “can them like any tomato.” If the goal is shelf-stable jars, crushed tomatoes are the most practical match: the fruit is peeled, heated, and broken down, so piece size stops driving the process.
Acidify, then pack hot
Wash the tomatoes and trim stems, cracks, and soft spots. Dip them in boiling water until the skins split, then move them to cold water and slip the skins off. Grape-tomato skins often split in less time than a large slicer, so work in small batches and do not leave them in the water until they turn to mush. Remove any core or damaged flesh. Quarter them.
Heat about one-sixth of the quarters in a large pot, crushing them so the released juice boils quickly. Keep the mixture at a boil and add the rest of the quarters gradually. Once all the fruit is in, boil gently for 5 minutes. This is the standard crushed-tomato preparation published for home canning, and it must be a hot pack.
Add the acid to each empty jar. Salt is optional and is for flavor only: 1/2 teaspoon per pint or 1 teaspoon per quart. Fill jars with the hot crushed tomatoes, leaving 1/2 inch of headspace. Remove air bubbles, wipe the rims, and adjust lids.
Use the time for crushed tomatoes, not a guessed whole-pack time
NCHFP boiling-water times for crushed tomatoes, with the required acid in every jar:
- At 0–1,000 feet: 35 minutes for pints, 45 minutes for quarts
- At 1,001–3,000 feet: 40 minutes for pints, 50 minutes for quarts
- At 3,001–6,000 feet: 45 minutes for pints, 55 minutes for quarts
- Above 6,000 feet: 50 minutes for pints, 60 minutes for quarts
Pressure canning is also an option and still requires the same acid. At 0–1,000 feet, a common tested option is 15 minutes at 11 pounds on a dial gauge or 10 pounds on a weighted gauge, for pints or quarts. Above that elevation the pressure rises; weighted-gauge canners generally move to 15 pounds. Check the current NCHFP table for your gauge type and elevation before you start. Do not shorten the time because the tomatoes are small.
Tomato juice is the other tested form sometimes suggested for small fruit. Wash, trim, and quarter; simmer until soft; press through a sieve or food mill; reheat the juice to boiling; acidify; and fill jars with 1/2 inch headspace. Boiling-water times at 0–1,000 feet are 35 minutes for pints and 40 minutes for quarts, with longer times at higher elevations. Yield is poor relative to larger paste tomatoes: plan on several pounds of grape tomatoes per quart of juice, and expect a sweeter, thicker juice than a standard canning tomato gives.
Do not add oil, fresh herbs, garlic, onions, peppers, or meat to these plain packs. Oil can shield bacteria and can damage lid gaskets. Low-acid additions change the product into something that needs its own tested recipe, often a pressure process. Salsa and seasoned sauce recipes from Extension can include tomatoes, but only in the amounts and with the acid and time printed in that recipe.
Freezing is the better default for grape tomatoes
Freezing skips the untested-pack problem. Illinois Extension specifically points to roasting cherry or grape tomatoes: toss with a little olive oil and roast at 450°F for about 20 to 25 minutes, until the skins blister and split, then cool and freeze. Roasting concentrates the sweetness that grape tomatoes are grown for, and the soft texture is exactly what a sauce or soup wants later.
Whole freezing also works. Wash, dry, remove stems, freeze in a single layer, then move them to freezer bags with the air pressed out. They will not thaw back to a salad tomato. Ice crystals rupture the cells, so the fruit collapses and releases juice. That is fine for simmered sauces, braises, and soup. Skins often slip off as they thaw, which is messy but not a safety issue. Use frozen grape tomatoes within about six to eight months for best quality. Label the bag with the date.
Previously frozen tomatoes can later be turned into juice or sauce and then canned, using the tested process for that product. Do not use frozen tomatoes to make canned salsa. Freezing changes the texture and how the fruit measures in a recipe that was tested with fresh tomatoes.
Drying keeps the flavor and skips the canner
Grape tomatoes dry well because they are dense and less watery than many cherry types. Wash, halve lengthwise, and place cut side up on dehydrator trays. Dry at about 135–140°F until they are leathery and no longer wet in the center, which often takes the better part of a day and sometimes longer. An oven set near 140°F with the door cracked for airflow can work, but it is slower and less even.
Dried halves keep for months in an airtight jar in a cool, dark cupboard. They rehydrate in warm water or go straight into pasta, grain salads, and oil-based dressings. Fully dried tomatoes packed in oil are not a substitute for canning: oil is not a tested preservation method for home use, and moisture trapped under oil is a botulism risk. If you want them in oil, store that jar in the refrigerator and use it within a short time.
Mistakes that turn a tomato jar into a gamble
- Packing grape tomatoes whole, especially with skins on, and borrowing a process time from a different tomato product.
- Skipping acid because the fruit tastes tart. Taste is not a pH measurement, and acid is required even in a pressure canner.
- Using fresh lemon juice, key lime juice, or ascorbic acid in place of bottled lemon juice or canning citric acid.
- Canning overripe fruit or tomatoes from frost-killed vines.
- Open-kettle canning, oven canning, or dishwasher canning. None of these are accepted methods.
- Adding oil, garlic, or a handful of herbs to a plain tomato pack.
- Reducing headspace to fit in a few more tomatoes, or tightening bands again after processing.
- Ignoring elevation. Water boils below 212°F as elevation rises, so boiling-water times get longer and pressure-canner weights go up.
After processing, cool jars undisturbed for 12 to 24 hours, remove the bands, and check seals. Refrigerate any unsealed jar and use it within a few days. Before opening a stored jar, look for a bulging lid, spurting liquid, mold, or an off odor. Discard those jars without tasting.
Which method fits the way you cook
Choose by end use, not by how full the counter looks.
Canning crushed grape tomatoes makes sense only if you already pressure-can or water-bath can, you are willing to peel and crush, and you want shelf-stable jars for winter sauces. The jars will taste sweeter than canned Romas, and the yield per pound is lower because of skins and seeds.
Freezing wins if the tomatoes will end up cooked anyway. Roasting first takes one pan and an hour; raw freezing takes minutes. Neither requires acid, a canner, or a tested process time.
Drying wins if you want a pantry ingredient with intense flavor and almost no storage space. It is the slowest active method and the one that best matches the concentrated sweetness of a ripe grape tomato.
A mixed approach is reasonable: dry the firmest, ripest fruit, roast-freeze the rest, and can only if you are set up to follow a current crushed-tomato or juice process exactly.
Frequently asked questions
Are grape tomatoes acidic enough to skip lemon juice? No. Variety, ripeness, and growing conditions all move tomato pH. Added bottled lemon juice, citric acid, or 5% vinegar is required for canned tomato products regardless of how tart the raw fruit tastes.
Can I leave the skins on if I pressure can? Tested tomato processes were built on peeled fruit. Leaving skins on, or packing grape tomatoes whole, is outside those tests. Pressure does not fix an untested preparation.
Do yellow or orange grape tomatoes follow different rules? Color does not create a separate tested process. The same caution applies: do not can them whole, and do not assume they are more acidic because they taste bright.
How many pounds do I need? Standard tomato figures are a rough guide only. Crushed tomatoes often take about 2 3/4 to 3 1/2 pounds per quart of larger fruit. Grape tomatoes yield less after peeling and trimming, so buy or pick extra if you are aiming for a canner load. Juice takes more again: NCHFP figures about 3 1/4 pounds of standard tomatoes per quart of juice.
What if a jar unseals in the cupboard? Do not taste it. Discard the contents and, if the jar itself is sound, reuse it only after washing. A failed seal on the counter the next morning can be refrigerated and used promptly; a seal that fails in storage should be treated as unsafe.