How to Make Green Tomato Relish in Canada (Chow-Chow)

Every Canadian gardener meets the same problem in late September: the frost is coming, and half the tomatoes are still hard and green. Green tomato relish — chow-chow, as it’s known from the Maritimes to rural Ontario — is the traditional answer. It turns the unripe crop that would otherwise go to the compost into a sweet-tangy, mustard-spiced condiment that lasts the winter (growing tomatoes in Canada).

This guide covers the Bernardin water-bath method. Per our food-safety policy we cite Bernardin for the exact vinegar amount and processing time rather than reprinting them — this is a recipe to make from a tested edition, with this page explaining the how and why.

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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. This site specifies 5% acidity as our own convention — most Bernardin recipes we have verified state no acidity percentage at all, and Canadian law guarantees only 4.1% for any vinegar. Every instruction about not reducing the acid is unchanged.

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

Green tomatoes are a bit more acidic than ripe ones, but a chow-chow also carries onions — and often peppers — which are low-acid. On their own, the finished vegetables aren’t reliably below the pH 4.6 line that separates water-bath-safe from pressure-canning-required.

Use the full vinegar amount your tested Bernardin recipe calls for, at 5% acidity (our convention, not a Bernardin figure). Never reduce it to soften the tang.

This is the same logic as corn relish and bread-and-butter pickles: low-acid vegetables are only safe in a boiling-water bath when a tested recipe acidifies the whole batch. Sugar and spices you can nudge to taste — they’re flavour, not safety. The vinegar is safety.

The overnight salt draw

The one step that separates a good chow-chow from a watery one:

Layer the chopped green tomatoes and onions with pickling salt and leave them overnight. This pulls the water out so the relish cooks down thick instead of weepy — and so the vinegar stays concentrated rather than diluted.

In the morning you drain thoroughly (and rinse off some of the salt if you prefer a milder result). The salt is a texture step, not the safety step — the vinegar still does the food-safety work.

What you need

• About 2.5 kg green (unripe) tomatoes — firm, hard, tart; the frost-crop
• 2–3 onions, plus peppers if your recipe calls for them
• Pickling salt for the overnight draw (non-iodized)
• Vinegar — the amount in your tested recipe, at 5% acidity (our convention, not a Bernardin figure — check the label)
• Sugar and whole pickling spices — mustard seed, celery seed, turmeric
• A large non-reactive bowl (glass or stainless — not aluminium) and a heavy pot
• 250 or 500 mL Bernardin jars with new SNAP lids
• Standard canning kit — jar lifter, headspace tool, funnel, water-bath canner, ladle

Method

1. Chop and salt. Core and chop the green tomatoes and onions. Layer with pickling salt in a non-reactive bowl, cover, and leave overnight (~12 hours).
2. Drain. In the morning, drain thoroughly in a colander; press or rinse to shed excess salt. Discard the liquid.
3. Cook with the vinegar. Combine the drained vegetables in a heavy pot with sugar, spices, and the full amount of vinegar your recipe specifies. Boil, then simmer, stirring often, until thick — usually 30–45 minutes.
4. Fill. Ladle hot relish into hot jars, leaving the headspace your Bernardin edition gives (usually 1 cm / ½ inch). Debubble; wipe rims; apply fresh SNAP lids fingertip-tight.
5. Process in the boiling water bath (which canner to buy) for the time in your Bernardin edition for green tomato relish, at your altitude band. Time starts at a full rolling boil.
6. Cool and check. Rest 5 minutes in the canner, lift to a towel, and leave 24 hours before checking seals.

If a jar doesn’t seal: the 24-hour rule applies.

Wait two weeks before eating

Like all relishes, chow-chow improves with jar-aging. Give it two weeks for the vinegar to mellow and the spices to meld before the first jar comes open.

Storage

• Cool, dark, dry place at room temperature
• Best quality about 12 months — Bernardin’s guidance is to use home-canned food within one year. That is a quality window, not an expiry: the jar is as safe as the process made it. Colour, flavour and bite fade.
• After opening: refrigerate, use within one week (HealthLink BC)
• Inspect before opening — discard any jar that bulges, leaks, or smells off

Corrected 31 Aug 2026: this page previously gave an after-opening window of 1–2 months. HealthLink BC File #22 publishes one week for any opened home-canned container — “Once the container has been opened, refrigerate leftovers, and use within one week.” Our longer figure was never attributed to anyone. The shelf life of the sealed jar is unchanged.

Ways to use green tomato relish

• The Maritime classic: on fish cakes and beside fried fish
• On hot dogs, burgers, and sausages
• Alongside roast pork, ham, or a Sunday roast
• Stirred into potato or egg salad
• On a cheese-and-cracker board
• Folded into a sharp cheddar sandwich

Common problems

• Relish is watery. The salt draw was skipped or too short, or the vegetables weren’t drained well. Salt overnight and drain hard next time.
• Too sharp / too sweet. Adjust sugar within reason next batch — but never lower the vinegar below the tested amount.
• Jar didn’t seal. The 24-hour rule.
• Bulging lid after weeks. Discard the whole jar; don’t taste. Low-acid vegetables in inadequate vinegar can support spoilage.

Next steps

• How to make corn relish — the late-summer relish, same vinegar-safety rule
• How to make bread-and-butter pickles — same mustard-celery spice family
• How to make fermented green tomatoes — the no-canning, lacto route for green tomatoes
• Canning altitude adjustments — required reading
• How long does home-canned food last — shelf-life context
• Water-bath canning pillar — the broader method