Ultimate Guide to Canning Tomatoes

Get started canning tomatoes with this easy water bath method. Follow these step-by-step instructions to preserve your garden harvest and enjoy diced tomatoes throughout the year!

Fresh tomatoes are amazing in the summer, in everything from Caprese Salad to BLT sandwiches to Homemade Pizza Sauce. They’re also one of the easiest plants to start when growing your own garden.

However, it only takes a few plants to suddenly become overrun with tomatoes. And when you’ve eaten your fill of Hearty Spaghetti Sauce and Tomato Basil Soup, what else can you possibly do with all those tomatoes?

That’s when it’s time to start canning tomatoes!

BEGINNER’S GUIDE TO CANNING TOMATOES

The idea of canning tomatoes (or any extra garden produce!) can sound scary, but it’s like riding a bike – once you get the hang of it, it’ll never be hard again.

Plus, this beginner’s guide will explain exactly what to do – step-by-step – so you can take advantage of garden harvest tomatoes in August, farmer’s market heirloom varieties, or even a good deal at the grocery store, all year long!

SUPPLIES FOR DICED TOMATOES CANNING

Before you can get to canning tomatoes, make sure you have all the equipment you need.

• Canning Jars: You need jars specifically made for canning (Ball and Weck are good brands) in either a 16-oz pint size or a 32-oz quart size. I tend to find the best deal on canning jars at Walmart, but those on Amazon are a good deal too. You can also reuse canning jars. If someone gives you gifts in mason jars, keep them!
• Flat Canning Lids: Canning lids come with canning jars when you buy them, but it’s best practice to use new lids every time you can so that they seal properly.
• Canning Rings: Also known as screw bands, you can reuse canning rings from canning jars. Do a quick count and make sure you have one ring for each jar you plan to use, and that they are in good shape, with no dents or rust.
• Canning Pot: You need one pot big enough to cover your jars plus 2″ of water. If you choose pint jars, you could probably use the typical 5-quart pot that comes with most cooking sets. If you’re using quart jars, you’ll need a big stock pot or canning pot.
• Trivet, Rack, or Dish Towel. Using racks in the pot helps keep the jars from rattling into each other and allows hot water to circulate underneath the jars.
• Small Saucepan: A small one like this that comes in your cooking set will work. It’s to keep the lids warm while you prepare the tomatoes and jars.
• Sharp Knife: For cutting diced tomatoes for canning. I love this one.
• Cutting board: To do your chopping. I like to use a large cutting board so that I have plenty of space.
• One cookie sheet OR another large pot OR the dishwasher: Some canners keep the jars warm in the oven on a cookie sheet; others keep them warm in a big pot of water, and I’ve even heard of folks running the jars through the dishwasher and keeping it closed to contain the heat. Choose whichever method suits you.

For most canning projects, you’ll probably already have most of these supplies. Double check you have enough jars in good condition (no chips or cracks), enough lids, and that your pots aren’t being used in another recipe, and you’re good to go!

OPTIONAL TOOLS FOR REMOVING TOMATO SKINS

Should you remove the skins from your tomatoes?

It depends on a) your preference and b) the type of tomato you’re canning.

If you like smooth, skinless tomatoes, remove the skins. If you’re canning tomatoes with tough skins (in general, the bigger the tomato, the tougher the skin), then you might want to remove the skins.

Me? My Roma and cherry tomatoes are only 1-2″ in diameter, and I don’t really care if there are skins in my sauce, so I kept the skins on.

If you DO want to remove the skins, in addition to the equipment above, you’ll also need:

• Medium Pot: If you want to remove the skin because it’s tough or doesn’t taste good, you’ll need another pot for dipping the tomatoes in hot water.
• A big bowl of ice water. To shock the tomatoes after the hot water. The temperature change makes it easy to peel the skins off.

CANNING TOMATOES RECIPE INGREDIENTS

This tutorial is for making diced canned tomatoes using ONLY tomatoes. If you want to can tomatoes using onion, peppers, garlic, carrots, or celery, you’re essentially canning salsa, and you should follow the appropriate process times.

For simple diced tomatoes for canning, you’ll need:

• Lots of firm raw tomatoes. Fresh ripe tomatoes are best for this recipe as they provide the most flavor! I recommend using Roma tomatoes or other larger, fleshy tomatoes. They have less juice and seeds, making them perfect for canning.
• Lemon juice. Bottled lemon juice is best for canning because the acidity level is consistent.
• Salt. If you’re going to use salt, make sure it’s a good one like Ava Jane’s Kitchen that doesn’t have microplastics! You can get a free 8oz. bag of sea salt right now (just pay shipping and handling!)

Note: This is everything you need for the cold-pack method, which is canning food that hasn’t been cooked. You can follow this guide for the hot-packing method of canning tomatoes, which involves cooking the tomatoes first.

HOW TO CANNING TOMATOES TUTORIAL

STEP 1: PREP YOUR EQUIPMENT

Prep Your Pot(s). Fill your water bath canner pot (either the stock pot or 5-quart pot) ⅔ full with water and bring it to a boil. This takes some time, so go ahead and start this first.

Optional, if Removing Skins: Fill the MEDIUM pot ⅔ full of water and bring to a boil. (See the next step for more on removing the skins from the tomatoes.) Fill a BIG BOWL halfway with ice water to create an ice bath.

Warm the Canning Jars. Jars must be the same temperature as the water you’re canning them in. If you’re using…

• Cookie Sheets: Preheat the oven to 250F. Place the empty jars on the cookie sheets and place them inside the oven.
• Large Pot: Fill the pot half full of water and place the empty jars inside. Bring to a simmer.

Simmer the Lids. Fill the SMALL saucepan with a couple of inches of water and place the lids inside. Bring to a simmer on a back burner.

Catch-Up. At this point, you should have up to 4 pots on the stove:

1. CANNING pot for water bath canning
2. COOKIE SHEET in the oven with jars on top, or a second large pot of water for warming jars
3. (optional) MEDIUM pot for de-skinning, plus a large bowl of ice water
4. SMALL saucepan for lids

Step 2: INSTRUCTIONS TO REMOVE THE SKINS (OPTIONAL)

Step 1. Remove the stems from the tomatoes and cut a small “X” at the bottom of the tomato using a paring knife. Place as many tomatoes as will comfortably fit in the medium pot, leaving about 1″ of water covering them. Leave the tomatoes in the boiling water for 30 seconds (use a kitchen timer).

Step 2. Use a slotted spoon to remove the hot tomatoes from the hot water and place them directly into the bowl of ice water.

Step 3. Allow them to sit in the water until they are cool to the touch.

Step 4. When cool, remove the tomatoes from the cold water and set aside to remove the skins. Repeat this process for the remaining tomatoes.

Step 5. When all the tomatoes have been boiled and cooled, peel the skins off and set them aside.

STEP 3: PREPARING DICED TOMATOES FOR CANNING

Step 1. Using your knife, carefully slice the tomatoes (peeled or unpeeled) into small pieces. The actual size of the chopped tomatoes is a matter of personal preference. I cut my tomatoes (1-2″ in diameter) into pieces that are ⅓″ – ½″ in size. Tomato quarters work if they are on the smaller side. You can also slightly crush the tomatoes if desired.

Remove and discard any bruised or blemished bits.

Step 2. As you’re working through the tomatoes, set aside any scraps and juice. They’ll come in handy in a moment! If you like, you can place your cutting board inside a rimmed baking sheet to collect any extra juices.

Remember that this tutorial is for the cold-packing method, not the hot-pack method. You want your tomatoes to be uncooked and raw.

STEP 4: JARRING TOMATOES

Step 1. When all your tomatoes are diced, it’s time to start jarring tomatoes! Pull out as many jars from the oven/warming pot as will fit in your boiling-water canner pot (mine holds 6) and start filling them up with the tomato mixture!

You want to pack tomatoes in the jars lightly but well. Shuffle the jar on the counter to help the tomatoes settle into the nooks and crannies. Leave about ½-inch headspace at the top of the jar for expansion.

Step 2. When your jars are filled, add lemon juice to each jar. Use 1 tablespoon for pint jars and 2 tablespoons for quart jars. You won’t taste this in the finished product!

Step 3. Measure salt into each jar. Use ½ teaspoon for pint jars and 1 teaspoon for quart jars.

Step 4. Fill jars with liquid, leaving ½″ of room at the top. You can fill the jars with either water or tomato puree. Personally, I choose tomato puree because it enhances the flavor of the homemade canned diced tomatoes and lets me use up my tomato scraps. (See the next step.)

Step 5. If you choose tomato puree, toss all your tomato juice, scraps, and skins you’ve been saving into a blender and puree until super smooth. You can press this tomato mixture through a sieve if you’d like (I usually don’t).

If you have leftover tomato puree after filling all of your jars, don’t waste it! Add it to Tomato Soup or Minestrone!

Step 6. As you fill the hot jars with puree (or water), slide a chopstick or butter knife around the inside edge of the jar to remove as many air bubbles as possible. Rotating the jar back and forth on the counter (in a half-circle motion) also helps. Make sure to wipe the rim if any moisture is on the lip.

STEP 5: PROCESSING TOMATOES IN A WATER BATH

Step 1. When the jars are filled, carefully remove the lid and ring from the small pot of simmering water. Place the lid on the can, then the ring on, securing just enough so the lid stays on and doesn’t fall off.

You don’t want to overly tighten the ring at this point. My trick is to turn it until it catches (and I can’t pull it straight off) and then another quarter turn. If you over-tighten the lid, pressure can build up and the jar can break during processing. The goal is just to hold the flat lid in place while it seals.

Step 2. Place the jars in the canning bath and let them boil submerged in water. Processing times depend on your added liquid:

• 45 minutes if you used water
• 85 minutes if you used tomato puree 

Set the timer and occasionally check the water level to ensure all the jars stay covered.

Note: This is for the water bath method at an altitude of 0-1000 feet above sea level. If your elevation is different or you are seeking a different method for canning tomatoes, use this guide from the National Center for Home Preservation.

STEP 6: COOLING THE CANNED DICED TOMATOES

Step 1. When the timer goes off, carefully remove the cans from the water bath (this is when a canning kit with a jar lifter comes in handy) and set them aside on a towel to cool for 24 hours until they reach room temperature. You should hear some popping over the hours as the lids seal themselves.

Step 2. Check for a good seal by pushing down on the center of the lid. If it doesn’t bounce back, you’re good. If it does bounce back, repeat the water bath method in the next batch, OR put unsealed jars in the refrigerator and include them in a meal in the next few days. You can also freeze the unsealed jars of tomatoes.

Note that after canning tomatoes, the diced tomatoes may separate and float above a layer of water inside the jar. That’s normal and totally fine! As they sit in the pantry, the tomatoes will naturally fall back into the liquid (and you can also give the jar a good stir once you open it).

Sealed canned diced tomatoes should last for 1-2 years in your pantry. Once opened, refrigerate any unused portion and use within one week.

STEP 7: REPEAT THE CANNING TOMATOES PROCESS

Step 1. When the first batch of canned tomatoes is cooling, check to ensure you have enough water in your pots, adding more water if necessary. Then start working on the second batch by repeating the same process.

Step 2. When all the tomatoes have been canned, cooled, and sealed, put them away and congratulate yourself for a job well done!

HOW TO CAN TOMATOES FAQS

WHAT ABOUT PRESSURE CANNING TOMATOES?

You can use a pressure canner to can tomatoes. However, using a water bath is easier for some because you don’t need any special equipment.

This is great news for those who are scared by the gauges, weighted gauge, and or gauge pressure on pressure canners!

The high acidity of the tomatoes makes them like other fruits when canning. Low-acid foods, on the other hand, would require a pressure canner.

MORE TOMATO RECIPES

If you prefer not to can tomatoes but still have an overabundance, try these yummy tomato-based recipes!