Best way to can tomatoes

The best way to can tomatoes is to hot pack them in a boiling water bath canner, using a tested recipe that adds bottled lemon juice or citric acid to ensure safe acidity. This method is simple, reliable, and works for whole, crushed, or diced tomatoes. If you want to can tomatoes with low-acid vegetables like onions or peppers, you must use a pressure canner instead. Here’s exactly how to do it, with the tools, steps, and varieties that work.

Why hot pack and water bath?

Hot packing means heating the tomatoes before putting them in jars. It removes air, helps prevent floating, and makes the tomatoes shrink, so you get more in each jar. Water bath canning is safe for tomatoes because they are naturally high in acid, but only if you add acid to every jar. The USDA recommends adding 2 tablespoons of bottled lemon juice or 1/2 teaspoon of citric acid per quart, and 1 tablespoon of lemon juice or 1/4 tea spoon of citric acid per pint. This brings the pH below 4.6, which prevents botulism.

Step-by-step: water bath canning tomatoes

1. Gather your tools

You need a water bath canner with a rack, canning jars (wide mouth pints or quarts), new lids, bands, a jar lifter, a bubble remover, and a clean towel. A food mill is helpful for making sauce or juice. Expect to pay $40 to $60 for a basic canner, $10 to $15 for a jar lifter and bubble remover kit, and $12 to $15 for a box of 12 pint jars with lids. Reusable lids like Tattler cost more upfront ($15 for 12) but last for years.

2. Prepare the tomatoes

Choose ripe, firm tomatoes. For canning, paste varieties like Roma, San Marzano, or Amish Paste have less water and more flesh, making them ideal. For a sweeter flavor, try ‘Sun Gold’ or ‘Yellow Pear’, but they are more watery. Wash the tomatoes, remove stems, and score a shallow X on the bottom. Blanch them in boiling water for 30 to 60 seconds, then plunge into ice water. The skins will slip off easily. Core and quarter them.

3. Hot pack the tomatoes

Put the prepared tomatoes in a large pot and bring to a boil, stirring constantly to prevent sticking. Reduce heat and simmer for 5 minutes. This softens them and releases juice. Ladle the hot tomatoes into hot jars, leaving 1/2 inch headspace. Add the required acid: 2 tablespoons lemon juice or 1/2 teaspoon citric acid per quart, or 1 tablespoon lemon juice or 1/4 teaspoon citric acid per pint. Add 1/2 teaspoon salt per quart if you like, but it’s optional.

4. Process in a water bath canner

Wipe the jar rims with a clean, damp cloth. Place the lids and screw on the bands finger tight. Put the jars in the canner with warm water, ensuring they are covered by 1 to 2 inches of water. Bring to a rolling boil. Process pints for 40 minutes and quarts for 45 minutes at altitudes up to 1,000 feet. For every 1,000 feet above that, add 5 minutes. When done, turn off heat, remove jars, and let cool undisturbed for 12 to 24 hours. Check that lids have sealed by pressing the center; it should not flex.

Pressure canning for low-acid additions

If you add onions, garlic, peppers, or herbs to your tomatoes, the pH may rise above 4.6, making water bath unsafe. In that case, use a pressure canner. Follow the same preparation steps, but process pints at 10 pounds pressure for 35 minutes and quarts for 40 minutes, adjusting for altitude. A pressure canner costs $100 to $300, but it’s essential for safe canning of low-acid foods. Always use a tested recipe from a reliable source like the USDA or your extension office.

Common mistakes to avoid

• Skipping the acid: Even if your tomatoes are very acidic, soil, variety, and ripeness affect pH. Always add acid.
• Overfilling jars: Too much food or too little headspace can cause siphoning or seal failure.
• Using cold pack: Cold packing (raw pack) is not recommended because it takes longer to heat, and tomatoes may float. Hot pack is better.
• Not adjusting for altitude: Water boils at lower temperatures at high altitudes, so you must increase processing time.

Yield and storage

A bushel of tomatoes (about 53 pounds) yields roughly 15 to 20 quarts of canned tomatoes, depending on variety and how much you trim. Store jars in a cool, dark place between 50°F and 70°F. Properly canned tomatoes will keep for 12 to 18 months, but flavor and quality decline over time. If a jar loses its seal, refrigerate and use within a few days.

FAQ

Can I can tomatoes without a water bath canner?

No. You must use a boiling water bath or pressure canner to ensure the jars reach a safe temperature. Steam canners are also acceptable if they hold at least 4 inches of water and process for the same times as water bath.

Do I really need to add lemon juice?

Yes. Tomatoes can vary in acidity, and adding bottled lemon juice or citric acid guarantees a safe pH. Use bottled lemon juice, not fresh, because the acidity is consistent.

Can I can green tomatoes the same way?

Green tomatoes are more acidic, so you can water bath them, but they are firmer and may need longer simmering. Use a tested recipe for green tomatoes, like pickled green tomatoes, which include vinegar.

How long do canned tomatoes last?

They are safe indefinitely if the seal holds, but for best quality, use within 12 to 18 months. After that, they may lose color and flavor.

The bottom line

The best way to can tomatoes is to hot pack them, add acid, and process in a water bath canner. This method is safe, simple, and yields delicious tomatoes for soups, stews, and sauces. If you want to add low-acid ingredients, switch to a pressure canner. Start with a small batch, follow the times exactly, and you’ll have pantry shelves full of summer goodness. Remember: safety first, and always use a tested recipe.