The Ultimate Guide to Canning Tomatoes | Making Sauce.

Throw on an apron, some opera and a pair of rubber boots …  you’re about to learn how to can tomatoes with a tomato press!  Plan to set aside 22 mason jars and a day to do this (unless you come from a large Italian family with plenty of helping hands.)

Rows of large mason jars filled with tomato sauce on rustic barn board shelves.

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I am on my third batch of canned tomatoes for the year. Because I grow my own tomatoes they don’t all ripen at the same time. That means I have to do a few smaller batches of them at the end of the summer instead of one big batch like I would if I was buying bushels of tomatoes at the market. 

So, you want to can your own tomatoes too do you?  You’re feeling like an Italian pioneer are you?  Good.  Glad to hear it.  Pressing and canning tomatoes is a bona fide “thing” and not something you can do without a bit of planning and a bit of know how.  Luckily for you … I’m here to show you how to do it.

I’ve been pressing my own tomatoes since I was in high school because I had no friends. Because I thought canning tomatoes was fun. Just kidding. I had a lot of friends. They just didn’t think I was any fun.

I’ve always used the recipe passed down from my mother who had it passed down to her from someone else.   I used that very recipe right up until the day I realized that recipe could kill me.

For the first decade of making this I just boiled the tomatoes,  ladled them into a hot jar and stuck them in a cupboard.  That’s the way they did it in the olden days and I like to do most things the traditional way.  The problem is … things have changed since the olden days.

Does tomato sauce need to be pressure canned?

Tomatoes have changed since the olden days.  They’ve been “improved” and tweaked and hybridized to within an inch of their lives.  This tomato mutation has caused the pH level of tomatoes to change over the past century.  Where tomatoes used to be high acid, they are gradually becoming lower and lower acid.

Things that are low acid are dangerous to can without either pressure canning them or giving them a hot water bath.  And by dangerous, I mean could kill you.

I don’t know about you but if I’m going to die from self inflicted stupidity I’d rather it be something fun like inhaling too much laughing gas or some sort of Bouncy House mishap.  Not from eating botulism infused pasta.

You do NOT need to pressure can tomatoes, but you DO need to water bath can them.

So you don’t need a pressure canner to can tomatoes. You just need a big pot that will cover your jars with at least 2″ of water.

Water bath canning means submerging the jars so they’re covered with a couple of inches of water and boiling them for a certain amount of time. You can do this with a water canning pot or even a regular pot if you have one that’s big enough.

Pressure canning means using a specialized piece of equipment – the pressure canner. Jars are put inside with a couple of inches of water in the bottom, the lid is locked and the pressure canner builds up pressure and steam inside. This build up changes the atmospheric pressure in the pot and the boiling point of the things inside it, which in turn kills pathogens. 

So … that is your canning lesson for the day.  What worked for gramma’s heirloom tomatoes (or any other veg/fruit) may not work for today’s Frankentomato.  The basic canning methods haven’t changed, but food has.

Large bushel basket filled with red Roma tomatoes.

How do you prepare tomatoes for canning?

Regardless of whether you grew your own tomatoes or are buying bushels from your grocery store or market, you have to prepare the tomatoes.

  • Tomatoes need to be washed before you put them through the press. If you don’t clean them thoroughly any dirt that’s on them will end up in the sauce. Not only dirt but bird poop. You can either lay them on a tarp and spray them with the hose or do what I do – wash them in the bathtub.
  • Before starting to press go through your tomatoes and cut any in half that are too big to fit through the top funnel. It’ll make your life easier later on when you’re pressing.

Do you have to cook tomatoes before canning them?

It depends. 

  • Some people put their tomatoes in a pot of very hot (not boiling) water to heat them up. The heat releases the juices from the tomato and makes them easier to run through the press with more juice being released.  This ISN’T necessary but it is a good practice.
  • After pressing the tomatoes have to be boiled for 15 minutes prior to their water bath canning.


How to Press Tomatoes.

Manual tomato press clamped to a black outdoor table over a stainless steel pot in outdoor courtyard.

To Process Tomatoes You Need a Manual or Electric Tomato Press.

A good quality tomato press is around $140.  Do not cheap out and buy a plastic one.  You’ll be cursing the tomatoes, the press and the person who sold it to you within 10 minutes.

Electric presses work much more quickly but are also more expensive.

This is the Electric Tomato Press I own and love.

This is the manual press I’m using in these photos.

Overhead shot of tomatoes being pushed into the funnel of a manual tomato shot

  1. Just drop the whole tomato into the press, skin and all (tomatoes that are too big to fit in the chute should be cut in half.)

You simply drop the whole tomato into the press and crank the handle.  You can fill the entire hopper up and just keep shoving them down the chute one by one.


Tomato sauce running out the chute of a manual tomato press with a red funnel on top.

2. Crank the handle and watch as the juice comes out one end and the discarded seeds and tomato skins out of the other.

The tomato press automatically filters the tomato pulp and juice from the seeds and skin. They come out of the end of the funnel as you can see. 

The seeds and skin come out one end, the good stuff out another.  Place a large stainless steel pot under the chute to catch the tomato juice.  Place another stainless steel pot or bag under the other side of the chute to catch the seeds and pulp.  Save them. You’re going to put those through the press another 1 or 2 times.

Very large stainless steel pot filled with tomato sauce simmering on a stove

3. Continue until all your tomatoes have been pressed.

4. Now take the seeds and skin you saved in a second pot and put those through the tomato press again. You can press the discards 1-2 times to get as much product out as possible.  The final time you run the pulp through it should be almost completely dry.

5. Fill a pot (or two) with your juice, put it on the stove and bring it to a boil. Boil for 15 minutes.

Once these steps are done you’re ready to process them.

How to preserve tomatoes in mason jars.

1.  Fill your canning pot with water and get it hot.

2.  Place clean mason jars (quart sized/4 cups) in a 210 °F oven.  (this prevents the jars from breaking when the hot tomatoes are funnelled into them)

3.  Line up bowls of brown sugar, salt and citric acid.

4.  Cover counter with dishtowels to sop up inevitable spills.

5.  Make sure you have a funnel and a ladle.  Jar tongs are handy to have too.

Canning tools on a white counter including tea towels, white bowls, ladles and funnels.

This whole event will be much easier if you have the proper tools, a funnel, a magnetic stick for picking up sealers out of boiling water (which you don’t need anymore since modern sealers don’t need to be heated before use) grabbing tongs for hot jars and a few other things. They aren’t expensive, in fact the entire kit of all the tools you need is only about $10, but they’re indispensable.


Overhead shot of small canning jar and bowls on red gingham tea towel.

  1. Once your tomatoes have come to a boil for 15 minutes, you can start jarring your sauce.
  2. Add 1 tsp brown sugar, 1/2 tsp citric acid and 1/2 tsp salt per quart jar.
  3. Put a funnel over your jar and ladle in hot tomato sauce to 1/2″ headspace* from the top of the jar.
  4. Wipe the rim of your mason jar with a wet paper towel or cloth to remove any drips that will interfere with the seal.
  5. Place the sealer on top and then the ring. Finger tighten only.
  6. Using tongs place the jar into the pot of hot water.
  7. Continue until the pot is full and then bring to a boil. Boil for 45 minutes.

*head space is VERY important. Too little headspace and your sauce will be sucked out of the jar and sealer while processing. Too much headspace and you might not get a proper seal.


Work with one jar at a time. Don’t try to do multiple jars.


Stainless steel ladle dripping tomato sauce into white funnel over jar.

Do yourself a BIG favour and cover your work surface with a few tea towels.  It’s gonna get messy.


5 mason jars in a pressure canner filled with water.

How many tomatoes do you need for canning?

1 bushel will get you 20-22 quarts of tomato juice.

2 bushels of tomatoes will get you 42-44 quarts.

Like so …


Two rows or freshly jarred tomatoes on barn board shelves.

These tomatoes will last me 2 years.  Now you’re probably wondering … what the hell are you supposed to do with them?  They are the perfect base for anything tomato related.   Just add spices and a little bit of tomato paste and you have a basic tomato sauce.  

Cook it for only an hour and it’ll taste very fresh and bright.   Cook it longer and it takes on a richer, smokier taste.  

Use them wherever you would use canned tomatoes or tomato sauce.   Like in chili (I happen to think my chili recipe is one of the best) or for a spicy tomato sauce or … best of all … for this … Gramma’s Spaghetti & Meatballs.  I also use this as the base of my homemade pizza sauce.  

Pressing & Canning Tomatoes

5 from 1 vote
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Servings: 22 jars
Calories: 27kcal


  • 1 bushel Plum Tomatoes
  • 1/2 cup Brown Sugar 1 tsp. per quart jar
  • 1/4 cup Coarse Salt 1/2 tsp. per quart jar
  • 1/4 cup Citric Acid 1/2 tsp. per quart jar


  • Fill a large pot with water and bring to a boil.  This is your hot water bath and should be large enough to fit several jars of tomatoes.
  • Preheat oven to 210 and place glass mason jars in oven to heat them so they don't crack when they're filled with the hot tomatoes.
  • When ready to start canning, pull a hot jar out of the oven with tongs.
  • Put 1 tsp. brown sugar, 1/2 tsp. coarse salt, 1/2 tsp citric acid into  jar.
  • Place a funnel over your 1 quart jar and ladle in hot tomatoe sauce to within 1/2 ” from the top of the jar. The "head space" is very important to get a proper seal. 
  • Remove funnel and wipe around the rim of the jar with a clean dishcloth or damp paper towel.
  • Take sealer ring from hot water and place on jar.
  • Screw screwband on. Barely finger tighten only. Do NOT overtighten.
  • Once you’ve filled enough jars to fill your canning pot, place your jars inside the pot of water using your jar tongs. Your water should be hot … almost boiling when you place the jars inside. You can also place the jars in the pot one by one as you fill them.
  • The water needs to cover your jars by a couple of inches.  
  • Put the lid on your canning pot and bring the canning water back up to the boil. Once at boiling again you can start your timer.
  • Your jars need to boil for 45 minutes.
  • Allow the jars to cool slightly in the water bath and then remove them to the counter where they should stay undisturbed for several hours. You will hear the seals "pop" as the pressure changes indicated you have a seal. Any unsealed jars need to be reprocessed or kept in the refrigerator to be used first.


1 bushel will get you 20-22 quarts of tomato juice. 2 bushels of tomatoes will get you 42-44 quarts.


Serving: 1jar | Calories: 27kcal | Carbohydrates: 5g | Protein: 1g | Sodium: 1287mg | Potassium: 7mg | Sugar: 5g | Calcium: 5mg | Iron: 1mg

Tips for Canning

    • Get everything washed, organized, laid out and ready to go the night before.
    • If you don’t have a canning pot, just use a large pot and place a metal trivet on the bottom.  (the water needs to circulate around and under each jar)
    • If your tomatoes are muddy and dirty wash them in the bathtub.  If a few only have a bit of surface dirt, just wipe them with a dishtowel.
    • Some people also add in a basil leaf to infuse basil flavour  into the sauce.  I do not.
    • Play opera while you’re spending the day pressing tomatoes. Even if you don’t like opera.

I’ve done this so many times it’s second nature so if you’re unsure or think I’ve left something out let me know.

Now get out there, buy a bushel of tomatoes and give it a shot.

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The Ultimate Guide to Canning Tomatoes | Making Sauce.


  1. I have a vegetable strainer attachment for my Kitchen Aid mixer that does this exactly!

    You do have to cut the tomatoes up into maybe max 2″ pieces. I bought a separate tray for it that is larger than the one it came with. The juice comes out the bottom and the seeds and skin come pooping out the side. I always put them through again to get all I can out of them. I grow heirloom tomatoes every year so I usually can two or three times over the course of the summer, and while this juicer would probably be less convenient to use than your dedicated tomato press if I were processing a whole bushel, I can easily do 10 lbs of tomatoes in short order. I have been doing this on my kitchen counter, but I think next time I will take it outside to my outdoor table so it will be at a better height for pushing the tomatoes down into the strainer, and I won’t be wiping tomato seeds off my kitchen cabinets.

    • Karen says:

      Yeah, I’m sure the mixer attachment works great! Same thing. You also have to cut the tomatoes to fit in the hopper of the electric tabletop model. Unless you want to mash them in, which inevitably ends up with exploding tomato everywhere. ~ karen!

  2. Kate Budacki says:

    Um, no.
    I love you Karen, I truly do, and I do lots of the things you recommend, but not this.
    I buy canned tomatoes from a local Italian market. Buy em by the case, and have been happy with them. They taste good, and there’s no mess.

  3. Simone Sequeira Lopes says:

    I just recently moved from Scottsdale, Arizona to my home country of Portugal, but in an area I am not at all familiar with. HOWEVER, I already see that my choice of residence, that is in Vale de Santarem, in the region of Ribatejo, where they grow ad infinitum tomatoes, produce some of the best wines – for the country and other parts of the world, and the list goes on. Anyway, just as I was getting ready to move to Portugal I came across one of your stories. Since then I have subscribed and always look forward to your emails/newletters/class-like lesson, but filled with a great sense of humour, and an intense passion for all that is food, especially where my interests are. Thank you for taking such time. Now that I live surrounded by tomato farms, I will have to give this a try. Made my first tomato sauce for my famous bolognese, well, even I found it out of this world. It will be hard to buy canned store tomato sauces now I say.

    I so appreciate your stories, your sense of humour, your exquisite skill in story telling and yet directions for recipes. I always write my a bit like you, and some find it tedious…they never make it onto the next email. Others impatiently wait for the next one. I have shared your link many times now and know that they all enjoy your posts as much as I do.

    Onto my new very very large veggie garden, never had one before, and ALL bio, sitting beautifully near my bio certified orange grove and many other citruses along with pine trees. So much to learn but I truly am living in a peaceful surrounding appreciating Mother Nature’s love and hard work. Might have to invite you over for a few days!

    Keep it up! Laughter is one my my best life ingredients.

  4. TucsonPatty says:

    This sounds like so many people get so much joy out of canning. That makes me happy to hear. I grew up canning out on the farm, and have done only a very small amount of it as an adult. My favorite was the apple butter we made from apples we picked ourselves. I just don’t think I want that mess, or to work that hard, but that was the most delicious apple butter, ever! Sweet apples, so no sugar, and cinnamon, cloves, and nutmeg, to taste. Delicious!!
    This brings back memories of the jars down in the cellar on the back porch. I hated going down there – spiders galore!

  5. Marie says:

    I have an old workhorse Champion Juicer. Will it work ok? Someone asked the same question but I don’t see a reply:
    Do you think you could use a juicer instead of a tomato press? Doesn’t it do the same thing-separate the juice from the pulp?
    Thanks so much!

    • Karen says:

      Hi Marie. I don’t have a juicer, so I can’t respond with any authority. All I can suggest is that you make tomato juice with it and see how it acts. Does it remove all the skin? (if not you may have to boil the tomatoes and remove the skin yourself) And will it remove the seeds? You probably don’t want juice full of seeds. Give those things a shot and see how it goes. I hope it works for you! ~ karen

  6. Jennifer says:

    Were my tomatoes supposed to separate? I have a bunch of tomato foam at the top of the jars, and a bunch of tomato water at the bottom. :( I forgot to boil them for 15 minutes before canning- is that why?

    • Karen says:

      That’s odd. When tomato juice separates the water would normally go to the top. I assume you gave them a boiling water bath? ~ karen

      • Jennifer says:

        No, I used the pressure canner with the rocker weight to make sure it was working correctly. I found my answer after I asked you- my tomatoes look like the picture.

      • Jennifer says:

        I am still struggling with this. I heated all the tomatoes before processing them. I didn’t boil them. More juice did come out, but I wonder how much was water? Because now both batches are extremely runny, even after heating them at the end. I am not sure what I am doing wrong?

      • Karen says:

        Hi Jennifer. It doesn’t sound like you’re doing anything wrong. What you’re making is basically a tomato juice. You then cook it to a proper thickness afterwards when you crack open a jar and are making a sauce. Does that help? ~ karen!

  7. Lisa says:

    I didn’t read every comment, but incase no one else mentioned this, if you have a kitchenaid stand mixer you can get the fruit/veggie strainer with food grinder attachment for around 100 USD. It fits in a shoebox for easy storage.

  8. Jen says:

    Because my tomatoes don’t seem to ripen at the same time, I pop them into a freezer bag and keep them frozen until I have enough to can. I’ve never used a press because I don’t care about seeds and the skins from the frozen tomatoes just slip off. Is there anything else you can use the tomato press for? Other than my canning equipment I really don’t like to have a lot of single use gadgets.

  9. Paula says:

    One tip is instead of tea towels, splurge on a plastic picnic table cover at the dollar store. When the job is done and the mess has been made you can simply throw it out and no cleaning necessary.

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