How to Can Tomatoes in Canada (Bernardin Method)

Home-canned tomatoes are the gateway recipe for serious Canadian preservers. Done right, a jar from August keeps you in pasta sauce, chili base, and tomato soup until next year’s harvest. Done wrong — without acidification — they’re one of the highest-risk foods in home canning.

This guide covers the water-bath canning method for crushed and whole-peeled tomatoes, following Bernardin and Health Canada. Per our food-safety policy, we cite Bernardin for processing times rather than reprinting them — open your edition next to this page.

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The single most important rule: acidify every jar

Bernardin’s tomato canning recipes all open with the same line, and we will too:

Add 1 tbsp bottled lemon juice per 500 mL jar, or 2 tbsp per 1 L jar. Alternative: ¼ tsp citric acid per 500 mL, or ½ tsp per 1 L.

This goes in every jar, every time, regardless of variety, regardless of whether the tomatoes taste tart. Modern tomato cultivars sit close to the pH 4.6 threshold that divides high-acid (water-bath safe) from low-acid (pressure-canning required). Adding lemon juice or citric acid pushes the contents reliably under 4.6 — which is what makes the water-bath method safe at all.

Bottled lemon juice only. Fresh lemon juice varies in acidity from lemon to lemon and is not safe here.

What you need

• 4.5–5 kg (10–11 lb) ripe paste tomatoes — Roma, San Marzano, Amish Paste. Beefsteaks work but yield more water and less pulp.
• Boiling water bath canner (a tall stockpot with a rack works)
• 7 × 500 mL Bernardin jars, or 3–4 × 1 L jars, plus new SNAP lids and bands
• Bottled lemon juice OR food-grade citric acid
• A large bowl of ice water for the peel-loosening dip
• A jar lifter, lid magnet, and headspace tool (the Bernardin canning kit covers all three)

Method (Bernardin-aligned)

1. Heat the canner. Fill the canner with enough water to cover the jars by 2.5 cm (1 inch). Bring to a simmer while you prep the tomatoes.
2. Sterilize the jars. Heat empty jars in simmering water (not boiling) — they’re ready to fill when they come out hot. Lids no longer need to be heated under Bernardin’s current SNAP-lid guidance, but rims still need to be clean.
3. Score and dip the tomatoes. Cut a shallow X in the bottom of each tomato. Dip in boiling water for 30–60 seconds until skins start to crack, then transfer to ice water. Slip off the skins with your fingers.
4. Core and quarter. Remove the cores and any green or bruised flesh.
5. Crush, or hot-pack whole. For crushed: simmer the quartered tomatoes for 5 minutes, mashing with a potato masher. For whole hot-pack: drop the peeled tomatoes into simmering water for 5 minutes.
6. Acidify each jar. Add lemon juice or citric acid directly to each empty hot jar in the amount above. Every jar. Don’t try to add it to the pot — it needs to be measured per jar.
7. Pack. Ladle hot tomatoes (and their liquid) into the jars. Leave 2 cm (¾ inch) headspace — more than the 1 cm used for jams. The extra space allows for the expansion of denser tomato pulp.
8. Debubble. Run a non-metallic spatula or chopstick around the inside of each jar to release trapped air. Re-check headspace.
9. Wipe the rims. Clean the rim of each jar with a damp cloth — any residue blocks the seal.
10. Apply lids. Centre a SNAP lid on each jar, then a band fingertip-tight (not over-tight; the air needs to escape during processing).
11. Process. Lower the jars into the canner using a jar lifter. Ensure they’re covered by 2.5 cm of water. Process for the time published in your Bernardin edition for crushed or whole tomatoes at your altitude band (see our altitude-adjustments guide for the band system). Start timing when the water returns to a full rolling boil.
12. Cool and check. Turn off the heat, wait 5 minutes, then transfer jars to a towel-lined counter. Let them cool undisturbed for 12–24 hours. The lids should “ping” as they seal. After cooling, press the centre of each lid — no give means a good seal.

If a jar didn’t seal: refrigerate and use within a week, or freeze. Never re-process a failed seal more than once, and never reuse a SNAP lid.

Where to look up the exact processing time

Open your Bernardin Complete Book of Home Preserving to the Tomatoes chapter. Each recipe (crushed, whole hot-pack, raw-pack, juice, sauce) has a separate time table for 500 mL and 1 L jars, with additions for each of the four Canadian altitude bands.

When our canning-times calculator finishes its editorial verification pass against Bernardin 2020, it’ll show those numbers directly. Until then, the calculator reads the food and altitude you select and links you back to Bernardin — which is the right authority anyway.

Storage and shelf-life

• Cool, dark place. A pantry or basement shelf. Avoid temperature swings.
• Best within 12–18 months. Sealed jars stay safe longer if the seal holds, but flavour and texture decline. Date your jars.
• Inspect before opening. Any bulging lid, off smell, foaming on opening, or visible mould = discard the entire contents without tasting. This is the boring rule that keeps the safety record clean.

What not to do

• Don’t skip the lemon juice or citric acid. It is not optional, even if you grew the tomatoes yourself and they taste tart.
• Don’t water-bath can tomato sauces with onions, peppers, or meat. Those become low-acid mixtures. Either use a tested high-acid salsa recipe with added vinegar, or pressure can a tested mixed recipe.
• Don’t use cracked or overripe tomatoes. They can carry mould the heat won’t fully kill.
• Don’t reuse SNAP lids. Bands, yes; lids, no.
• Don’t process for shorter than published. If you saved 30 seconds at processing, eat it within a week from the fridge instead of storing it.

Next steps

• Read the altitude-adjustments guide to find your band.
• Skim the water-bath canning pillar page for the broader context on which foods can be water-bath canned.
• When the canning-times calculator is populated against Bernardin, you’ll be able to look up the exact processing time in one click.