Canning a Big Tomato Harvest: Passata, Sugo & Tomato Sauce

Canning a Big Tomato Harvest

High summer always brings the same problem: too many tomatoes at once. The solution: canning. One busy Saturday afternoon yields enough of a stock to last the whole year.

Passata – the Most Versatile Tomato Base

Passata is puréed, strained tomato juice – the foundation of all tomato sauces.

Ingredients (makes about 6 liters):

• 8–10 kg ripe beefsteak or vine tomatoes
• 2 tsp salt
• per litre of passata 2 tbsp + 2 tsp bottled lemon juice or a heaped ½ tsp citric acid
• Optional: fresh basil

Steps:

1. Wash the tomatoes, remove the stem end, and roughly dice.
2. Cook soft in a large pot without water (20–30 min.).
3. Push through a food mill or fine sieve – the skins and seeds stay behind.
4. Bring back to a boil, season with salt.
5. Acidify: stir in 2 tbsp + 2 tsp bottled lemon juice or a heaped ½ tsp citric acid per litre of passata, for 0.5 l jars half that per jar (National Center for Home Food Preservation, NCHFP: 1 tbsp or ¼ tsp per pint = 0.47 l, 2 tbsp or ½ tsp per quart = 0.95 l – rounded up here because 0.5 l and 1 l jars are slightly larger). Do not reduce the amount: tomatoes are borderline low-acid, and too little acid leaves a risk of botulism. This is not a matter of taste but the safety step – without added acid tomatoes sit right at the pH threshold and are not considered safely canned (see "Safe Canning: Avoiding Botulism").
6. Fill boiling hot into sterilized bottles/jars, seal immediately.
7. Process in a water bath 30 min. at 100 °C.

Shelf life: 1–2 years, stored dark and cool.

Sugo – Ready-Made Tomato Sauce (for the Freezer)

Sugo is more richly seasoned than passata – ready to use straight as a pasta sauce.

In addition to the passata base:

• 4 garlic cloves (sautéed in olive oil)
• 2 onions (diced, cooked until translucent)
• 1 bunch fresh basil
• 2 tbsp olive oil, salt, pepper, a pinch of sugar
• Optional: chili, oregano, rosemary

Add everything to the finished passata, simmer 20 min. and adjust the seasoning. Do not can sugo – freeze it: with onion, garlic and oil, tomato sauce counts as low-acid – tested times exist only for a pressure canner, not for a water bath (National Center for Home Food Preservation, NCHFP, "Spaghetti Sauce without Meat"). Let it cool, freeze in portions and label with the date. Keep in the fridge (7 °C at most) and use within 2–3 days, otherwise freeze: at −18 °C cooked vegetables keep for up to 12 months (German Federal Institute for Risk Assessment, BfR, "Pre-cooking for several days"). For jars in the pantry, can the plain passata and add onion, garlic and oil only when you cook with it.

Oven-Dried Tomatoes

For an intense flavor all winter long:

1. Halve or quarter the tomatoes, remove the seeds
2. Place on a baking sheet, cut side up
3. Dry in the oven at 40–50 °C with the door slightly open, as the BZfE advises, or in a dehydrator at about 60 °C according to the NCHFP. This takes many hours – the tomatoes are only done when they are leathery with no moist spots left
4. Only store fully dried tomatoes airtight – this way they last through the winter
5. If you would rather preserve them in olive oil (with garlic and herbs): keep the jar in the fridge only and eat them no later than the day after making them (BfR). Oil excludes oxygen, and the BfR advises against storing vegetables and garlic in oil at room temperature – more on this in "Safe Canning: Avoiding Botulism"

Frozen Tomato Cubes

The fastest method – no cooking required:

• Peel the tomatoes (briefly in boiling water, then ice water), dice
• Freeze in portioned bags → add straight to sauces, soups, and stews

Yield & Planning

• 1 kg of tomatoes yields about 600–700 ml of passata
• For a year's supply (family of 4): can 15–20 kg of tomatoes
• Good varieties for canning: San Marzano, Ochsenherz (oxheart), Moneymaker

Sources

• National Center for Home Food Preservation (NCHFP), University of Georgia: Tomato Acidification Directions, accessed 4 Oct 2026
• National Center for Home Food Preservation (NCHFP), University of Georgia: Spaghetti Sauce without Meat, accessed 5 Oct 2026
• German Federal Institute for Risk Assessment (BfR): Rare but avoidable: questions and answers about botulism, as of 12 Nov 2025, accessed 4 Oct 2026
• German Federal Institute for Risk Assessment (BfR): Pre-cooking for several days: what should I bear in mind?, as of 8 Jul 2025, accessed 5 Oct 2026
• German Federal Centre for Nutrition (BZfE): Getrocknete Leckereien, accessed 5 Oct 2026
• National Center for Home Food Preservation (NCHFP), University of Georgia: Food Dehydrators, accessed 5 Oct 2026

The sources support individual statements in this article. The organisations named have neither reviewed nor endorsed it.