How to Make Tomato Ketchup in Canada (Water-Bath Method)

Homemade tomato ketchup is a September project worth doing at least once — it’s deeper and less sweet than the bottle, and it’s the best thing to do with the last of a paste-tomato glut. It’s also, quietly, an acidified canning recipe, which means the safety rules are stricter than they look (growing tomatoes in Canada).

This guide covers the water-bath method following Bernardin and Québec, and explains the how and why. The one ketchup Bernardin publishes online is set out in full at the foot of this page — but it is a fruit ketchup, not a plain tomato one, so for plain tomato ketchup you still work from a tested edition. The reason that distinction matters is the whole subject of the next section.

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Corrected 31 Aug 2026: the page put “(5% acidity)” directly beside “your tested Bernardin recipe”, which reads as though Bernardin published the percentage. They mostly do not — the Bernardin ketchup this site has verified states a vinegar volume with no strength at all. This site specifies 5% acidity as our own convention, and Canadian law guarantees only 4.1% for any vinegar. Every instruction about not reducing the acid is unchanged.

The rule that keeps ketchup safe: don’t cut the vinegar

Ketchup is mostly tomatoes, which sit close to the pH 4.6 line, plus onions, which are genuinely low-acid. Left to themselves that mixture would need pressure canning. What makes ketchup safe in a boiling-water bath is the vinegar, added in a tested amount that brings the whole batch reliably below pH 4.6.

Use the full vinegar amount your tested Bernardin recipe calls for. Never reduce it to make the ketchup milder.

This is the same logic as why you can’t water-bath spaghetti sauce: low-acid ingredients are only safe in the boiling-water bath when a tested recipe acidifies the whole batch. Sugar and salt you can adjust to taste — they’re flavour, not safety. Vinegar is safety.

What you need

• About 5.5 kg (12 lb) ripe paste tomatoes — Roma or San Marzano thicken far faster than watery field tomatoes
• One onion, plus whole pickling spices for a spice bag (cinnamon, cloves, allspice, celery seed)
• White vinegar — the amount in your tested recipe, at 5% acidity (our convention, not a Bernardin figure — check the label)
• Sugar and salt to taste
• A food mill or fine sieve, and a wide, heavy pot for reducing
• 250 mL Bernardin jars with new SNAP lids — ketchup keeps best in small jars
• Standard canning kit — jar lifter, headspace tool, funnel, water-bath canner, ladle (which canner to buy)

The method (mostly hands-off simmering)

1. Sieve. Simmer quartered tomatoes and onion until soft, then run through a food mill to remove skins and seeds.
2. Reduce with the spice bag. Return the purée to a wide pot, add the tied spices, and simmer gently — stirring often so it doesn’t scorch — until it’s reduced by about half and mounds on a spoon. Budget 1–2 hours.
3. Season and acidify. Remove the spice bag. Stir in sugar and salt to taste, then the full amount of vinegar your recipe specifies. Simmer a few minutes to blend.
4. Fill. Ladle hot ketchup into hot 250 mL jars, leaving 1 cm (½ inch) headspace. Wipe rims, apply fresh SNAP lids fingertip-tight.
5. Process in the boiling water bath for the time your own recipe gives, at your altitude band. Time starts at a full rolling boil. If you are making Bernardin’s Fruit of the Vine Ketchup, that time is below; if you are making a plain tomato ketchup, it is not the same number.
6. Cool and check. Rest 5 minutes in the canner, lift the jars out without tilting them, and leave 24 hours undisturbed before checking seals. Don’t retighten the bands.

The one ketchup Bernardin publishes online

Fruit of the Vine Ketchup — and the first thing to say about it is that it is not a plain tomato ketchup. Bernardin files it under Fruit, not Tomatoes, and it is half peach and apple by volume. They rate it Expert.

That matters more than it sounds. Its 15 minutes belongs to this mixture — this fruit, this ½ cup of vinegar, this honey, sieved to this consistency, in this jar size. A plain tomato ketchup is a different density with a different acid load, and its time is not this one. Same reasoning as crushed versus whole tomatoes, where Bernardin’s own two recipes differ by 50 minutes.

Makes about 4 × 250 mL jars.

• 4 cups (1000 mL) prepared tomatoes — about 2 lb (1 kg), 8 medium
• 4 cups (1000 mL) chopped peaches — about 2.5 lb (1.1 kg), 8–10 medium
• 2 cups (500 mL) chopped apples — about 4 medium
• 1 cup (250 mL) finely chopped onion
• 3 cloves garlic, minced
• 1 cup (250 mL) liquid honey
• ½ cup (125 mL) white vinegar
• 2 tsp (10 mL) dry mustard
• 1 tsp (5 mL) each salt, pepper and ground cloves
• ½ tsp (2 mL) ground allspice
• ¼ tsp (1 mL) cayenne pepper

Blanch, peel and chop the tomatoes and peaches, measuring 4 cups of each; peel, core and chop the apples to 2 cups. Combine the three fruits in a large stainless steel saucepan and heat gently, mashing until the juices flow. Add the onion and garlic, bring to a boil, cover, and boil gently 10 minutes.

Press the cooked mixture through a sieve to yield 5 cups (1250 mL) — that yield is the step to measure, not eyeball, because everything after it is balanced against it. Return it to the saucepan, add the honey, vinegar and all the spices, bring to a boil, then boil gently uncovered, stirring occasionally, 45 minutes or until it reaches the consistency you want.

Ladle into hot 250 mL jars leaving 1 cm (½ inch) headspace. Process 15 minutes at altitudes up to 305 m, then wait 5 minutes, lift the jars out without tilting, and cool 24 hours undisturbed.

A note on the jar size: Bernardin’s own directions say “250 or 236 ml mason jars.” 236 mL is the US half-pint — the two are close enough that they list them together here, and it is a rare acknowledgement of the gap our US-to-Canadian conversion guide exists to explain. Don’t read it as a general licence to swap jar sizes; on this recipe Bernardin has said the two are interchangeable, and on others they have not.

Common questions

It’s still thin after an hour. Keep going — ketchup reduces by half or more, and paste tomatoes get there faster than field tomatoes. Never thicken with starch for canning; it blocks heat penetration.

A jar didn’t seal. Refrigerate and use within a few days (Bernardin’s figure), or reprocess immediately with a fresh lid. See jar didn’t seal — is it safe.

How long does it keep? Sealed, cool, and dark, about a year for best quality. See how long home-canned food lasts.

Related tomato guides

• How to can tomato juice
• How to can tomato sauce
• How to can whole and crushed tomatoes
• Preserving tomatoes in Canada — the full hub