How to Can Tomatoes
Learn how to safely water-bath can tomatoes with modern USDA guidelines. Foolproof, beginner-friendly instructions for perfect jars every time!
Equipment
- water bath canner
- quart mason jars, lids and rings
- jar lifter and funnel
- food mill optional
- large stock pot
Ingredients
- 12 pounds tomatoes approximately
- 8 tablespoons lemon juice see chart for other acid options
- 4 teaspoons salt optional
Instructions
- Wash tomatoes. Rinse thoroughly under cool running water and let them dry on a clean towel. It is no longer recommended to use dish soap to wash tomatoes for canning.
- Peel and core tomatoes. See note below about blanching vs. using a food mill for this process.
- Use a big dutch oven or stock pot to cook the tomatoes. Simmer peeled and diced, halved or milled tomatoes for 30 minutes.
- Wash jars, lids and rings in hot soapy water and rinse well. Keep the jars hot before adding the tomatoes.
- Place clean jars on a towel-lined counter, then add 2 tablespoons of bottled lemon juice (or another acid from the chart above) to each jar before filling. Optional: add 1 teaspoon of salt per quart.
- Ladle hot tomatoes into jars, leaving ½ inch of headspace. Remove air bubbles by sliding a non-metal utensil around the inside of the jar. Adjust tomato level if needed. Wipe rims with a vinegar-dampened cloth. Place new lids and screw on bands until fingertip tight.
- Fill canner halfway with hot (≈180°F) water for hot-pack. Load jars upright with a jar lifter. Add boiling water to cover jars by more than one inch.
- Start the timer only after water reaches a rolling boil. For crushed or diced tomatoes, process quart jars for 45 min (at 0–1,000 ft). Process packed whole/halved tomatoes, pints for 40 min. If packing whole/halved tomatoes, pints are processed for 40 min. See the chart below to adjust for your elevation and jar size.If at any point the jars are no longer submerged, add water and restart the timer once it comes to a simmer.
- When the processing time is complete, turn off the heat and carefully remove the canner lid, tilting it away from you to avoid a face full of steam. Let the jars sit in the hot water for 5 minutes. This helps prevent thermal shock, which can cause jars to crack. It also gives the boiling action inside the jars a chance to settle.
- Use your jar lifter to lift each jar straight up and out of the water. Keep jars upright—tilting them can interfere with proper sealing. Place jars on a towel-lined counter or cooling rack, leaving at least one inch of space between them for airflow. Be safe! Never set a hot jar on a cool surface- it can explode!
- Leave jars undisturbed at room temperature for 12–24 hours. During this time, you’ll hear a few satisfying “pings” as the lids seal. Resist the urge to press on the lids or tighten the bands—you want the natural vacuum to form without interference.
- Wipe jars clean with a damp cloth or vinegar if sticky. Label the jars with contents and date. Remove rings.Store in a cool, dark place (50–70°F). Avoid damp areas to prevent rust.
- Jars last 18 months or longer when stored correctly. After that, they may still be safe, but quality may decline with undesirable flavor changes or color fading.
Notes
Troubleshooting
- Tomatoes & Water Separate
- Common with paste varieties like roma tomatoes.
- Safe to eat—just shake the jar before using.
- Cloudy Liquid:
- Usually caused by hard water or tomato starches.
- Add a splash of vinegar to canner water to prevent this next time.
- Unsealed Jars:
- Causes: dirty rims, overtightened bands, defective lids, or water level too low.
- Solution: Replace lid and reprocess, or refrigerate and use quickly.
Nutrition
Calories: 252kcalCarbohydrates: 55gProtein: 12gFat: 3gSaturated Fat: 0.4gPolyunsaturated Fat: 1gMonounsaturated Fat: 0.4gSodium: 2394mgPotassium: 3256mgFiber: 16gSugar: 37gVitamin A: 11337IUVitamin C: 198mgCalcium: 139mgIron: 4mg
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