preserve · Preserve
How to Can Tomatoes at Home
Home canning tomatoes preserves your harvest using boiling water bath processing. You'll need ripe tomatoes, lemon juice or citric acid for safety, clean jars, and about 45 minutes of processing time. The key is adding acid to prevent botulism and following tested processing times exactly.
- Total time: 1 hr 45 min
- Hands-on: 45 min
- Difficulty: Medium
Ingredients
- 2 tbsp lemon juice
- 1/2 tsp citric acid
- 1 tsp salt
Step by step
- Prepare your equipment. Wash jars, lids, and rings in hot soapy water. Keep jars hot in a 200°F oven or dishwasher. Fill your canner with enough water to cover jars by 1-2 inches and start heating.
- Prepare the tomatoes. Wash tomatoes thoroughly. Bring a large pot of water to boil. Drop tomatoes in for 30-60 seconds until skins crack, then plunge into ice water. Slip off skins, remove cores, and quarter large tomatoes.
- Add acid to jars. Add 2 tablespoons lemon juice OR 1/2 teaspoon citric acid to each quart jar. For pints, use 1 tablespoon lemon juice OR 1/4 teaspoon citric acid. This prevents botulism growth.
- Pack the jars. Fill jars with tomatoes, pressing gently to release juice and eliminate air bubbles. Leave 1/2 inch headspace. Add 1 teaspoon salt per quart if desired.
- Seal and process. Wipe jar rims clean, place lids, and screw rings fingertip tight. Process in boiling water: pints for 40 minutes, quarts for 45 minutes. Start timing when water returns to full boil.
- Cool and check seals. Remove jars and cool on towels for 12-24 hours. Check that lids don't flex when pressed. Properly sealed jars will keep for 1-2 years in a cool, dark place.
Tips & troubleshooting
- Use only firm, ripe tomatoes at peak season for best results
- Never skip the added acid even if using very acidic tomato varieties
- Adjust processing time for altitude: add 5 minutes above 3000 feet, 10 minutes above 6000 feet
- Reuse rings but always use new lids for proper sealing
- If a jar doesn't seal, refrigerate and use within a week or reprocess with a new lid
Variations
- Crushed Tomatoes. Heat tomatoes quickly to boiling while crushing, then pack hot into jars. Reduces processing time but requires more active cooking.
- Tomato Juice. Extract juice using a food mill or juicer, heat to simmering, then can. Same acid and processing requirements apply.
- Seasoned Tomatoes. Add herbs, garlic, or onions directly to jars before processing. Stick to tested recipes to ensure safe acidity levels.
Questions
- Can I use fresh lemon juice instead of bottled?
- Stick to bottled lemon juice or citric acid. Fresh lemon juice varies in acidity and won't guarantee the pH level needed for safe canning.
- What if my tomatoes aren't very juicy?
- Add boiling water to cover the tomatoes in the jar, maintaining the 1/2 inch headspace. The acid requirement stays the same.
- How do I know if my canned tomatoes went bad?
- Look for bulging lids, off odors when opened, or any signs of mold. When in doubt, throw it out. Properly canned tomatoes should smell fresh and look bright red.
- Can I pressure can tomatoes instead?
- Yes, pressure canning works too. Process at 11 pounds pressure for 25 minutes for both pints and quarts. You still need to add acid for best quality and safety.