Roma tomatoes are the workhorse of home canning: dense flesh, fewer seeds, and less water than most slicing tomatoes. That means fuller jars, less watery sauce later, and less time spent cooking liquid off the stove.
They are still tomatoes. Modern varieties can sit near or above pH 4.6, which is the cutoff that keeps Clostridium botulinum from growing. That is why every tested home-canning method for whole, crushed, or juiced tomatoes requires added acid, whether you use a boiling-water canner or a pressure canner.
This guide follows USDA and National Center for Home Food Preservation (NCHFP) procedures. It tells you which pack style to choose, how much fruit you need, how to acidify each jar, and how long to process at your altitude.
Why Roma Tomatoes Can Better Than Juicy Slicers
Paste types such as Roma, San Marzano-type, and Amish Paste have thick walls and small seed cavities. You get more usable flesh per pound and less gel that separates in the jar.
That matters in three practical ways:
- Yield. Crushed Romas pack tighter than beefsteaks. NCHFP averages about 2¾ pounds of tomatoes per quart of crushed product and about 3 pounds per quart of whole or halved tomatoes. A 53-pound bushel typically yields 15 to 21 quarts of whole or halved tomatoes, or 17 to 20 quarts crushed.
- Texture. Whole or halved Romas hold their shape better than watery slicers after processing.
- Later cooking. Sauce, soup, and chili start thicker, so you spend less time reducing.
Flavor is another story. Many grocery Romas are bred for shipping and processing, not for eating raw. They still can well. If you grow your own, other paste types (Amish Paste, Granadero, Opalka) often taste richer; the canning process itself does not change.
Yellow and orange paste tomatoes are not lower in acid than red ones. They taste sweeter because they have more sugar. Acidify them the same way.
What You Must Get Right Before You Start
Three rules are non-negotiable. Skip any of them and a sealed lid does not make the jar safe.
Add acid to every jar
USDA researchers found that cultivar, ripeness, and growing conditions can push tomato pH above 4.6. Adding a measured amount of acid brings the product back into the range where botulism spores cannot grow, and it is required for both water-bath and pressure processes. The published pressure times were not developed for unacidified tomatoes.
Add the acid to the empty jar first so every jar gets the full amount:
| Acid | Per pint | Per quart |
|---|---|---|
| Bottled lemon juice | 1 tablespoon | 2 tablespoons |
| Citric acid | ¼ teaspoon | ½ teaspoon |
| Vinegar, 5% acidity | 2 tablespoons | 4 tablespoons |
Use bottled lemon juice, not fresh. Fresh juice varies in acidity. Vinegar is safe in the amounts above but can change flavor. Citric acid changes flavor the least. A teaspoon of sugar per quart can soften the tartness; it does not replace acid. Never reduce the acid.
Do not use tomato canning tablets. They are not a substitute.
Peel the tomatoes
Tested times assume peeled fruit. Skins can interfere with heat penetration and leave tough, bitter bits in the jar. NCHFP still recommends peeling unless a specific recipe says otherwise.
Use sound, ripe fruit from living vines
Choose firm, fully ripe Romas without large cracks, rot, or mold. Cut out small bruises. Do not can tomatoes from dead or frost-killed vines; acidity and quality drop, and those fruits belong in the freezer or the compost. Overripe fruit is fine if you trim bad spots, but it separates more in the jar.
A pressure cooker is not a pressure canner. Use a canner built for home canning, with a rack and a weighted or dial gauge.
Choose the Pack Style That Matches How You Cook
The “best” method depends on how you will use the jars, not on which one sounds most traditional.
Crushed tomatoes, no added liquid (hot pack only) Best everyday choice for Romas. You get a thick, ready-to-use product for soup, chili, and quick sauce. Processing time is shorter than packing whole fruit in juice. This is the method most people should start with.
Whole or halved tomatoes packed in water (hot or raw pack) Best if you want pieces that stay intact for stews or to crush later. Water dilutes flavor slightly. Processing time is moderate.
Whole or halved tomatoes packed raw with no added liquid Densest pack and strongest tomato flavor. You press the fruit until its own juice fills the gaps. Water-bath time jumps to 85 minutes at low altitude because the pack is dense. Use this when you want whole tomatoes and you have the time.
Packed in tomato juice Similar long process to the no-liquid pack. Useful if you already have juice on hand. Not necessary for most Roma batches.
Do not invent a hybrid: do not add oil, do not thicken with flour or cornstarch before canning, and do not drop untested vegetables into the jar and keep the tomato processing time. Oil can trap water droplets where spores survive; thickeners change heat penetration.
Equipment and Yield Planning
You need:
- Mason-type canning jars (pints or quarts; no half-gallons for tomatoes)
- New two-piece lids
- Boiling-water canner with a rack, or a pressure canner
- Jar lifter, bubble tool or plastic knife, clean towels
- Large pot for peeling and, if crushing, heating
- Bottled lemon juice or food-grade citric acid
Approximate amounts from NCHFP:
- Whole or halved: 21 pounds for 7 quarts, 13 pounds for 9 pints
- Crushed: 22 pounds for 7 quarts, 14 pounds for 9 pints
Romas often do a little better than those averages because they carry less water, but plan with the official numbers so you are not short mid-batch.
Look up your altitude before you process. Water boils at a lower temperature as elevation rises, so times or pressures increase. County extension offices and many weather apps list elevation.
How to Peel Roma Tomatoes Quickly
- Wash the fruit under running water.
- Score a shallow X on the blossom end if you want easier peeling.
- Lower a few tomatoes at a time into boiling water for 30 to 60 seconds, until the skins split.
- Move them to cold water.
- Slip off skins, cut out cores, and trim bruises.
Work in small batches so the first tomatoes do not sit and soften while you finish the rest.
Method 1: Crushed Roma Tomatoes (Most Useful Everyday Jar)
This is NCHFP’s crushed-tomato procedure with no added liquid. Hot pack only.
- Peel, core, and quarter the tomatoes.
- Put about one-sixth of the quarters in a wide pot. Heat them quickly and crush with a spoon or potato masher so they release juice. Stir so they do not scorch.
- When that juice is boiling, add the remaining quarters gradually. You do not have to crush the rest; heat and stirring will soften them.
- When all tomatoes are in the pot, boil gently for 5 minutes.
- Put acid (and optional salt: 1 teaspoon per quart or ½ teaspoon per pint) into hot jars.
- Fill immediately with hot tomatoes, leaving ½-inch headspace.
- Remove air bubbles, wipe rims, apply lids fingertip-tight.
Water-bath times for crushed tomatoes
| Jar size | 0–1,000 ft | 1,001–3,000 ft | 3,001–6,000 ft | Above 6,000 ft |
|---|---|---|---|---|
| Pints | 35 min | 40 | 45 | 50 |
| Quarts | 45 min | 50 | 55 | 60 |
Pressure-canner options for crushed tomatoes
Weighted-gauge canner, pints or quarts:
- 20 minutes at 5 lb (0–1,000 ft) or 10 lb (above 1,000 ft)
- or 15 minutes at 10 lb (0–1,000 ft) or 15 lb (above 1,000 ft)
Dial-gauge canner, pints or quarts:
- 20 minutes at 6 / 7 / 8 / 9 lb for 0–2,000 / 2,001–4,000 / 4,001–6,000 / 6,001–8,000 ft
- or 15 minutes at 11 / 12 / 13 / 14 lb for those same bands
Acid still goes in the jar if you pressure can.
Method 2: Whole or Halved Romas Packed in Water
Good when you want pieces, not a crushed mash. Hot pack usually gives less floating than raw pack.
- Peel, core, and leave whole or cut in half.
- Add acid and optional salt to hot jars.
- Raw pack: Pack raw tomatoes into jars. Cover with boiling water, ½-inch headspace.
Hot pack: Cover peeled tomatoes with water, boil gently 5 minutes, then pack tomatoes and cooking liquid to ½-inch headspace.
- Remove bubbles, wipe rims, apply lids.
Water-bath times (hot or raw pack)
| Jar size | 0–1,000 ft | 1,001–3,000 ft | 3,001–6,000 ft | Above 6,000 ft |
|---|---|---|---|---|
| Pints | 40 min | 45 | 50 | 55 |
| Quarts | 45 min | 50 | 55 | 60 |
Pressure-canner options (hot or raw pack)
Weighted-gauge, pints or quarts:
- 15 minutes at 5 lb (0–1,000 ft) or 10 lb (above 1,000 ft)
- or 10 minutes at 10 lb (0–1,000 ft) or 15 lb (above 1,000 ft)
Dial-gauge, pints or quarts:
- 15 minutes at 6 / 7 / 8 / 9 lb across the elevation bands above
- or 10 minutes at 11 / 12 / 13 / 14 lb
Method 3: Whole or Halved Romas Packed Raw, No Added Liquid
Use this when you want a dense, juice-packed jar and you are willing to process longer.
- Peel, core, leave whole or halve.
- Add acid and optional salt to the jars.
- Pack raw tomatoes and press until juice fills the spaces. Leave ½-inch headspace.
- Remove bubbles, wipe rims, apply lids.
Water-bath times
Pints or quarts: 85 minutes (0–1,000 ft), 90 (1,001–3,000), 95 (3,001–6,000), 100 (above 6,000).
Pressure-canner options
Weighted-gauge, pints or quarts:
- 40 minutes at 5 lb (0–1,000 ft) or 10 lb (above 1,000 ft)
- or 25 minutes at 10 lb (0–1,000 ft) or 15 lb (above 1,000 ft)
Dial-gauge, pints or quarts:
- 40 minutes at 6 / 7 / 8 / 9 lb
- or 25 minutes at 11 / 12 / 13 / 14 lb
Those longer times exist because a tight pack of solids heats more slowly than tomatoes floating in water.
How to Process and Cool the Jars
Boiling-water canner. Jars must be covered by at least 1 inch of water. Start the timer only after the water returns to a full rolling boil. When time is up, turn off the heat, wait 5 minutes, then lift jars out.
Pressure canner. Follow the manufacturer’s venting instructions (usually 10 minutes of steady steam before you weight or close the petcock). Start timing only when the canner reaches the required pressure. If pressure drops, bring it back up and restart the timer. Depressurize naturally; do not rush the lid.
Set jars upright on a towel. Do not tighten bands. Leave them undisturbed 12 to 24 hours. Then check seals: the lid should be concave and should not flex. Remove bands, wash jars, label with product and date, and store without the rings. Unsealed jars can be refrigerated and used soon, frozen, or reprocessed within 24 hours in a clean jar with a new lid and the full process time.
Mistakes That Ruin Safety or Quality
Skipping acid because the tomatoes “taste tart.” Taste is not pH. Some paste types and many modern hybrids sit above 4.6 even when they taste sharp. Add the measured acid every time.
Using a fresh-salsa recipe and water-bathing it. Onions, peppers, and low-acid add-ins change the product. Use a tested salsa recipe or pressure-can only recipes written for those mixtures.
Starting the water-bath timer too early. Time under a simmer does not count.
Ignoring altitude. A 40-minute pint process at sea level is not the same process in the mountains.
Packing unpeeled fruit, adding oil, or thickening first. Those changes are outside tested methods.
Canning in a pressure cooker or Instant Pot canning program unless the appliance is a tested canner and you follow a researched process for that device. Most electric multi-cookers are not substitutes.
Using half-gallon jars. There is no tested tomato process for that size.
What “Normal” Looks Like After Canning
Floating fruit is common with raw pack. Trapped air in raw tissue lifts the tomatoes; they often settle during storage. It is a quality issue, not a safety failure, if the jar sealed and was processed correctly.
Separation — a clear layer of liquid with solids on top or bottom — comes from pectin-breaking enzymes. Heating tomatoes quickly at the start of a crushed batch reduces it. Overripe fruit separates more. Shake or stir after opening.
Siphoning (lost liquid, fruit sitting above the liquid line) happens when jars are packed too tight, headspace is short, bubbles were left in, or jars were cooled too fast. If the seal is strong and there is no spoilage, the food is still usable; keep pieces covered with liquid after opening and refrigerate.
Do not eat from a jar that is bulging, leaking, spurting, moldy, or foul-smelling. Do not taste to “check.” Discard it where pets and children cannot get it. When a batch was not acidified or not processed by a current tested method, do not keep it on the shelf.
How to Store and Use Canned Romas
Store sealed jars in a cool, dark, dry place. Quality is best within a year to 18 months; many jars remain fine longer if seals hold and there is no sign of spoilage.
After opening, refrigerate and use within about a week.
Crushed Romas drop straight into chili, minestrone, shakshuka, and weeknight pasta. Whole water-packed Romas work in braises; drain or keep the liquid as part of the cooking broth. If a recipe needs thick sauce, simmer the jar contents uncovered until they reduce. You already did the safety work in the canner; stove time now is only about texture.
Frequently Asked Questions
Do I still add lemon juice if I pressure can? Yes. Published pressure times for these tomato products assume acidified fruit. They are a shorter, hotter equivalent of the water-bath process, not a low-acid botulism process.
Can I leave the skins on? Not for these tested whole, halved, or crushed procedures. Peel unless you are following a different researched recipe that was developed with skins on.
Can I mix Romas with beefsteaks in the same jar? Yes, as long as you still peel, acidify, and process for the product you actually packed (crushed vs. whole in water, and so on). Expect more liquid and more separation from the slicers.
Can I can green or underripe Romas the same way? Unripe tomatoes may be canned with the same procedures and the same acid. Do not skip acidification just because green fruit is usually more acidic.
Why not can tomato sauce with garlic, onion, and olive oil in the same jar? Those extras are low-acid. Use a tested sauce or salsa recipe that accounts for them, or can plain tomatoes and add aromatics when you cook.
How many plants should I grow if I want a winter’s worth of quarts? Yield varies by season, but a determinate Roma-type often concentrates harvest into a short window, which suits one or two canning days. Use the pound-per-quart figures above and work backward from how many quarts you actually cook through in a year.
Where should I verify times if this page and an old cookbook disagree? Use the current NCHFP or USDA Complete Guide to Home Canning tables, or your state extension service. Older books often omit acid and use outdated times.
Roma tomatoes reward a careful process more than a complicated one: peel, acidify, pick one tested pack, and process for your altitude. That is enough to put dense, useful jars on the shelf without guessing.