Red tomatoes in a boiling pot of water and on a wooden chopping block

Canned tomatoes are, hands down, pantry superstars. Having a jar on hand means you’re always minutes away from salsas, soups, stews, spaghetti sauce; you name it. Sure, you can buy canned tomatoes. But canning your own captures the very best flavours of summer, so you can enjoy that freshness all winter long. Plus, you know exactly what’s in it (goodbye preservatives, additives, and added sugars).

Canning tomatoes at home may seem like a big project that requires special tools, a ton of space, bushels of tomatoes and an Italian Nonna at your side. But believe us, it’s a lot easier than you think. With this handy guide, there’s no Nonna needed to stock your pantry with fresh tomatoes for months (hello, money-saver!).

I first learned how to can tomatoes working on a farm (many years ago!) and continued the tradition when I moved to the city. That’s where my Italian neighbours hosted a yearly tomato canning operation in their garage. Now, it’s something I do with my kids, right in our kitchen. They love being put to work washing, peeling, and then smashing tomatoes with their hands. The best part is that they’re more likely to eat foods that use the sauce (even my picky eater!) since they had a hand in making it.

What Kind of Tomatoes to Use for Canning

The best of the best are San Marzanos. Can’t find them? Look for tomatoes that tend to have less juice, are a bit more firm and meatier. Keep an eye out for those with smaller and fewer seeds. These varieties include Romas, Big Mamas and Amish Paste.

You’ll need about nine pounds of tomatoes, plus salt, citric acid or lemon juice (from a bottle) and fresh basil leaves.

What Equipment You Need for Canning Tomatoes

  • Eight x 500 millilitre Mason jars. You can reuse jars, but you must buy new lids; old ones won’t seal properly
  • Jar tongs to ensure you can safely lower and lift the jars out of boiling water
  • A funnel to pour tomatoes into the jars to prevent spills (no time for extra messes here!)
  • A large pot to boil the tomatoes and the jars in
  • A large bowl to hold an ice water bath and cool down your tomatoes
  • A canning rack, or if you want to DIY it, use old canning rings or a silicone trivet instead

How to Can Tomatoes

The whole canning process from start to finish takes about three to four hours, which may seem like a lot, we know, but it’s a really fun afternoon activity to do with your kids. It will also save you loads of time on busy weekdays when you need to get fresh, healthy dinners on the table, fast.

1Boil the water.

Fill your large pot with water and bring it to a boil. Easy-peasy!

Red tomatoes on a wooden chopping block Image source: Sarah Grossman

2Wash and score tomatoes.

While the water is coming to a boil, wash the tomatoes really well and cut an ‘X’ into the skin at the bottom of each tomato.

How kids can help: Get kids involved in the easy steps, like washing. Little ones love this part. Set them up with big bowls of water and strainers in the backyard. Warning: there will be splashing!

3Boil and ice-bath tomatoes.

In a large bowl, prepare an ice bath. Once the water is boiling, carefully slip the tomatoes in and boil for one to two minutes. You want to work in batches so the water temperature doesn’t drop. After two minutes, remove tomatoes with a slotted spoon and place them directly in the ice bath.

Image source: Sarah Grossman

4Peel, chop and smash tomatoes.

Wait for the tomatoes to slightly cool and then peel them. This is the perfect step for kids to help out. We make it like a cool science experiment in our house, showing how peels slide off easily once tomatoes are cooked. Tell them to tug right near the ‘X’ if they’re having trouble.

Once skinned, slice the tomatoes into quarters and place them in a large bowl (juices and all). Smash with a masher, in a food processor or with your kids’ hands.

How kids can help: Kids love squeezing the tomatoes, but they also love pushing the food processor’s button if the tomatoes are too hot to squeeze. What kid doesn’t love buttons?

5Sanitize the jars and lids.

Clean your pot and place a wire rack, silicone trivet or old canning jar rings at the bottom of it. Place the jars on top and fill with enough water to cover the jars by an inch. Boil for 10 minutes to sterilize. (See below for more information on sterilizing.) Place a smaller pot with water on the stove, bring to a boil, then simmer and place the lids in (not the rings) for 10 minutes. Wash the rings by hand. Using your tongs, carefully remove the jars and lids and place them on a clean towel or rack.

Image source: Sarah Grossman

6Fill the jars.

Put a few basil leaves (my kids do this part), half a teaspoon of salt and one tablespoon of bottled lemon juice or a quarter teaspoon of citric acid into each jar. Fill the jars with the smashed tomatoes using the funnel but leave two centimetres of space at the top. Use the end of a wooden spoon or a wooden chopstick and run it along the jar’s inside walls to remove any air bubbles.

Tomato cans in a pot Image source: Sarah Grossman

7Seal the jars.

Wipe the rims of the jars with a clean paper towel. Place the lids on, then screw the rings around as tight as you can using only your fingers tips (not the palm of your hand). Place the rack, trivet or old rings back into the bottom of the pot, put the filled jars inside and cover so they’re submerged by at least five centimetres of water. Put a lid on the pot and bring to a boil for 35 minutes (if you’re using one litre jars, boil for 45 minutes).

Typically, you boil your 500 millilitre jars of tomatoes for 35 minutes, but, did you know that the amount of time actually varies depending on your altitude?

  • 305 to 914 metres above sea level add five minutes
  • 915 to 1,829 metres, add 10 minutes
  • 1,830 to 2,438 metres, add 15 minutes
  • 2,439 to 3,048 metres, add 20 minutes.[1]
Canned tomatoes Image source: Sarah Grossman

8Listen for the pop.

Using your tongs, remove the jars from the water, place them on a towel on the counter to cool, and listen for the lid’s pop. This means the jars are sealed. The lids should be slightly curved down at the center and when you press on it, it shouldn’t ping back up. If some of the jars don’t pop, place them in the fridge and use them up within two days. Otherwise, label and store in a cool dark place. They’re good for up to a year.

How kids can help: Tell them to sit and listen for the ‘pop’. They’ll take this step very seriously and get incredibly excited when they hear it!

What Recipes to Try

Shashouka Image source: theHUB from Walmart.ca

Why we love it: Now that you have all this beautiful tomato sauce, you gotta use it! As we colder weather comes, make this warming breakfast that slowly and perfectly poaches eggs in a rich tomato sauce.

Missing any ingredients? Order eggs, onions, peppers and more through Walmart.ca Grocery Pickup & Delivery.

Spicy sundried tomato soup Image source: theHUB from Walmart.ca

Why we love it: Making soup in the cold Canadian winter is a must. It’s the perfect time to pull out one of your jars of sauce and combine it with sundried tomatoes and cayenne for a slightly spicy, sweet and earthy dish.

Missing any ingredients? Order garlic, cayenne pepper, sun-dried tomatoes and more through Walmart.ca Grocery Pickup & Delivery.

Why we love it: Ready to can more than just tomatoes? Add some pep to your salsa and make this sweet and spicy version with a whole variety of peppers. The best part of homemade salsa? You can adjust to your own spice level.

Missing any ingredients? Order cider vinegar, red peppers, oregano and more through Walmart.ca Grocery Pickup & Delivery.

What You Need to Know About Sterilizing Jars

How do you sterilize Mason jars?

Sterilizing jars is essential to prevent botulism and other microbes that could make you sick. If you want to be extra safe, you can first wash your jars in the dishwasher or warm soapy water. Be sure to boil for 10 minutes to destroy any possible toxins actively.

How do you sterilize canning jars in the oven?

This is a controversial one because some people believe it’s safe, while others do not. We always go to the canning gurus for the final word, i.e., the National Center for Home Food Preservation. They say that placing jars in the oven can be dangerous because the temperature varies with each oven. Dry heat can’t penetrate the jar, and often, glass jars can break or, worse, explode in the oven.[2] Meaning, jars don’t get sterilized. Let’s stick with the water bath.

Shop Canning Must-Haves

Article Sources

  1. National Centre for Home Food Preservation. Selecting, Preparing and Canning Tomatoes.
  2. National Centre for Home Food Preservation. Frequently Asked Canning Questions.

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