Canning Tomatoes. A Novice’s Journey

Every summer we get tons and tons of tomatoes and vegetabales from our neighbor, so many vegetables in fact that we can’t eat them fast enough.

I’m talking hundreds and hundreds of tomatoes, eggplant, zucchinis, peppers, cucumbers, and chilies. I froze a bunch to use throughout the year but my freezer was getting pretty full.

I gave a bunch of veggies to friends too but I still had loads of vegetables waiting to be used. Finally with the remainder of the hundreds of tomatoes, squashes, and eggplants I decided to make giant pots of marinara sauce, and for the first time in my life I learnt how to can and jar my tomatoes!

Canning? Me?

I had no clue where to begin. What an adventure I was in for. Having no idea what to do I scoured the Internet for an EASY recipe that did not involve buying any new equipment. Here is what I learnt through my canning journey.

There are three basic rules to follow when canning vegetables, in this case specifically tomatoes.

  • Sterilizing the bottles is very important!  Any deep pot can be used for sterilizing jars as long as the pots are deep enough to submerge the jars completely in boiling water.
  •  I did wonder if the jars and lids could be re-used after the sauce was finished.  They can! I have been re-using my jars for new batches of marinara sauce for a couple of years now.
  • Most importantly when canning tomatoes and tomato sauce – use store bought lemon juice must be added to the tomatoes to assure they are canned properly and to prevent bacteria from developing.  
  • I thought I could use fresh lemon juice since we have so many lemons always available, but every article I read was very clear – it must be store bought lemon juice!! 2 tbsp lemon juice for every quart of tomatoes!!
  • Why? Because fresh lemon juice does not have a consistent acidity and neither do fresh tomatoes. To ensure that canned tomatoes have a safe pH zone, store bought lemon or lime juice which maintains a consistent acidity must be added to canned tomatoes to keep them safe and edible long term.

I found a great article from web site  Canning in Jars that explains why using store bought lemon juice is important in canning tomatoes:

 “When it comes to recipes that involve tomatoes or other moderately acidic ingredients, I specify bottled lemon juice. The reason for this is that bottled lemon (or lime) juice has been uniformly acidified so that it has a consistent and dependable acid level.

When you’re canning things like tomatoes (or watermelon jelly) and you need to reliably get those foods into a safe pH zone, that consistency is important.” from web site Canning in Jars

Here is another article from web site Penn State Extension Food Preservation that articulates really well why citric acid or store bought lemon juice is so important in canning tomatoes:

Why do we add lemon juice or citric acid when canning tomatoes?  Answer – Tomatoes were once considered an acid food that could be safely canned in a boiling-water canner. However, because of the potential for botulism when some newer, less acidic tomato varieties are canned, certain precautions must now be taken.  

Add 1 tablespoon bottled lemon juice to pints and 2 tablespoons bottled lemon juice to quarts of tomatoes. Or add one-fourth teaspoon crystalline citric acid to pints and one-half teaspoon crystalline citric acid to quarts of tomatoes.

Acid can be added directly to jars before filling. Four tablespoons of 5 percent acidity vinegar per quart may be used instead of lemon juice or citric acid, however, it may cause undesirable flavor changes. Add sugar to offset acid taste if desired.

Note: Don’t use fresh lemon juice as its acidity varies!! Tomato canning tablets should not be used as they are ineffective!”  Penn State Extension Food Preservation

  • Once the jars are filling with sauce, close the lid and submerge the entire bottle in boiling water. The water should be over the lid. This assures that the air gets removed from the jar.
  • During the canning process air bubbles are removed from the bottle. The best way to know if this actually happened is to see how the lid appears after the jar has been submerged completely in boiling water for at least 20-30 minutes.
  • The lid should be concave (meaning it should be curved downward rather than bulging out). Sometimes you even hear a “pop” sound when the jar is sealed tight.

I’ve been canning using the above three steps for a couple of years now and it positively works!

In fact, it works so well that I have jars of marinara sauce that I canned two years ago that are still sealed tight – so tight that I have a hard time opening the jar and get frustrated at my own successful canning ability 😀.

If you are wondering how marinara sauce can even last that long without us all devouring it?

I hide them in the pantry because my kids if had a choice of store bought or homemade marinara sauce opt for the homemade! And they just gobble it down.  

I have to remind them to savor each bite as that marinara sauce took hours to make – cutting pounds of vegetables, cooking them into a creamy sauce, and then canning them for preservation.  “Please slow down and enjoy each bite. It took a long time to make the sauce.”  To which their response is “But Mom the sauce is for eating. What are you saving it for?”  Can’t argue with that.


To savor the flavors of summertime tomatoes all throughout the year, give canning tomatoes a try.  These tomatoes will bring thoughts of warm summer days even in the cold of winter.


Happy Canning. 🍅

11 thoughts on “Canning Tomatoes. A Novice’s Journey”

  1. Super! I am going to start canning now with my abundant tomato crop this year! Thanks for the wonderful write up.

  2. Since you have such a variety of tomatoes, I would recommend canning individual varieties, or at least varieties of the same color, separately. For example, keep all the red ones together, and keep all the yellow ones together. Red and green mixed together does not look very appetizing. Also (and you probably know much more about herbs than I do), there are some herbs that should not be canned with the sauce, but instead added later. I do not remember which are which because I add no herbs to canned sauce, but there are some herbs that give it an odd flavor if stored too long.
    At the end of the year, when frost ruins the plants, you might want to pickle some of the green tomatoes that do not ripen.

      1. Next time? Did you mix them this time? I am sure there is nothing wrong with that, particularly if you think that the flavors go together. I just dislike the odd colors. (Almost all of my tomatoes are red anyway, and I do not can the green ones – they get eaten fresh first.)

  3. Wonderful way of preserving the Tomatoes by Canning them scientifically . My mom used to make the Best Tomato ” Jams” by canning tomatoes with Sugar , Cinnamom and red peppercorns and a little salt , We used to love using this as a Sandwich spread for our School Luncheons . mom was great at making Jams ( fruits )

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