Preserving
How to Can Tomatoes Safely
Preserving · 5 min read · Updated November 14, 2026
You can tomatoes safely at home by packing clean jars with prepared tomatoes and added lemon juice, then processing them in a boiling water bath using a tested recipe. Tomatoes sit right on the line between high acid and low acid foods, so the added acid and a tested method are what make water bath canning safe for them.
Safe canning is not hard, but it is exact. Use a current tested recipe from the Ball guide or the National Center for Home Food Preservation, and follow it as written. Processing times change with jar size and altitude, so this guide walks through the method and points you to a tested recipe for your exact times. If you are growing your own, our guide on how to grow tomatoes covers the harvest side.
Gather gear and good tomatoes
You need a large water bath canner with a rack, or a deep pot with a rack in the bottom so jars do not touch the pot base. Also gather canning jars, new flat lids, bands, a jar lifter, a funnel, and bottled lemon juice. Wash jars and keep them hot until filling.
Work with sound, ripe tomatoes. Cut away any bruised, moldy, or spoiled spots, and compost the bad ones. Only good fruit goes in jars. Our guide on how to store potatoes so they last covers the same pick only the best rule for storage crops.
Prep the tomatoes and add the acid
Most recipes peel the tomatoes first. Dip them in boiling water for about a minute, then into cold water, and the skins slip off. Core them, and cut them as your recipe directs, whole, halved, or crushed in their own juice.
Add bottled lemon juice to each jar in the amount your tested recipe calls for. Bottled juice has a steady acid level, which fresh lemons do not, and that acid is a safety step, not a flavor choice. Do not skip it, and do not swap in fresh juice.
Fill jars and leave the right headspace
Fill hot jars with the hot tomatoes and their juice, leaving the headspace your tested recipe calls for. Run a clean plastic or wooden tool around the inside to release air bubbles, wipe each rim clean, and set on a new flat and band, snug but not forced tight.
A dirty rim is the top cause of jars that fail to seal. Check every rim with a clean damp cloth before the lid goes on.
Process in the water bath and check seals
Lower the jars into the canner, cover them with water as your recipe directs, and bring the pot to a full boil. Start timing only when the water is boiling hard, and process for the time your tested recipe gives for your jar size and altitude. Times go up as altitude rises, so if you live in the hills, look up your adjustment rather than guessing.
When time is up, turn off the heat, wait a few minutes, and lift jars out with the jar lifter, keeping them upright. Set them on a towel and do not touch the lids for 12 to 24 hours. Then check each seal: the center of the lid should be down and firm. Label, date, and store sealed jars in a cool dark place. Any jar that did not seal goes in the fridge and gets used first. The same water bath method is used for jam in our guide on how to make jam at home.
Frequently asked questions
What kind of jars should I use?
Glass jars made for canning, with two piece lids (a flat and a band). Use jars with no chips or cracks. Bands can be reused if they are not rusty or bent, but flats must be new each time so they seal well.
Can I use a water bath for all vegetables?
A water bath handles high acid foods like tomatoes with added acid, pickles, and jam. Low acid foods like plain vegetables, meat, and beans must go in a pressure canner. Never water bath low acid food, no matter what an old recipe says.
Is it safe if my tomatoes look cloudy?
Cloudiness alone is not a danger sign and can come from minerals or starch. But if a jar is cloudy and also has a bulging lid, spurting liquid, or an off smell, throw it out without tasting it.
How long do home canned tomatoes keep?
Sealed jars keep best quality for about a year in a cool, dark place. They are not unsafe the day after a year passes, but flavor and color fade, so rotate old jars to the front and use them first.
What if a jar does not seal?
Do not rescue it and do not taste it. When in doubt, throw it out. Botulism has no smell or taste you can count on, which is why tested recipes and correct processing matter so much.