How to Can Tomatoes

how to can tomoatoes

In this tutorial, you’ll learn how to can tomatoes from your garden to preserve them. This guide explains both the tools and technique for home canning.

Once you have blanched your tomatoes, now is the time to can them.

Canning doesn’t require a lot of equipment but it is somewhat specialized.  The good news is it is all fairly inexpensive and most grocery/super stores carry everything you need.


Canning Pot-your pot needs to be big enough that it can hold your jars covered by a couple inches of water.  For some, their large stockpot will work and that is what I use when I can small jelly jars.  For my bigger jars (pint and quart) I have a larger pot just for canning.  It is a very thin pot so it really isn’t good for much besides boiling water.  However, once you have one, they last forever.  Mine pictured above is the one my mom canned in the whole time I was growing up.

Jars-It doesn’t matter what brand you get, you just want to be sure they are fit for canning.  Again, you can get these at any grocery store, many garage sales, or raid your mom/grandma’s cabinets (that is where I got most of mine).  What size you use depends on what you are canning and how many people you feed.  I like to can tomatoes in pint jars because there are only two of us.  I can pickles in 1/2 pint jars so that I can give them away.  My mom favors quart jars because you don’t need as many.  All up to you.

Flats-the flat seals on top of the jar during the water bath process  Make sure you buy wide mouth vs. regular size depending on what kind of jar you have.  Don’t use flats that have been sitting around for eons, they might not seal and we just did all this work only to have 10 pints of tomatoes in the fridge.

Rings-they go over the flats and around the jars.  If you buy your jars, they come with rings.  If you garage sale your jars, they might not.  Again, if you have to buy rings, match them to your jars. 

Funnel-Again, cheap, pick one up at the grocery store.  Mine was gifted to me but otherwise I might have splurged on this one because I am trying to get away from plastic.

Canning Tongs-They look funky, but they are designed to easily pick up your hot jars.  Regular ones just don’t do the same work.

Regular Tongs-Easier to use for things like picking up your flats and rings than the canning tongs.

Grippy Thing-not pictured, but one of these is nice to tighten the rings on the jars before they hop back in the water bath.

How to sanitize your canning jars:

To sanitize you jars, fill your canning pot with warm water and place your jars and rings inside.  I always like to put in 1-2 extra rings in case I drop one on the floor after they have been sanitized.  Also, be sure that your rings match whatever sized mouths on the jars.  Make sure the jars are covered by at least 2 inches of water.  Bring water to a full boil and boil for 10 minutes.

While you are waiting for your jars to sanitize, fill a small bowl with very warm water and put your flats in the water.  Once you put the flats in the water, you cannot reuse them so don’t put in more than you need.

How to fill your jars with tomatoes:

Once the jars have been sanitized, using your canning tongs, pull a jar out of the boiling water and fill with blanched, chopped up tomatoes leaving about 1/2 of space at the top.  The funnel makes this endeavor easier.  Using a butter knife, jab into the tomatoes several time to remove the air bubbles. Wipe the rim of the jar with a damp cloth.

Using your regular tongs, remove a flat from the water and place on top if the jar.  This bit is a tad tricky.  Do not touch the bottom of the flat with your fingers.  Once the flat is in place, grab a ring out of your boiling water (again with the regular tongs, remember boiling water) and place it on the jar.  Using your grippy thing, tighten the ring on the jar.

Repeat above steps until you have run out of tomatoes.  If you have a partial jar, you can fill the remainder with water or you can just freeze it.  The jar cannot be 1/2 full of air.

Place canned tomatoes back into the water bath and boil for 40 minutes.  If you water has stopped boiling while you were processing the jars, you cannot start your 40 minutes until the water is back to a solid boil.

After 40 minutes, remove jars from water and allow to sit overnight.  Remove rings and store.  Any jars that did not seal should be stored int he refrigerator and used within a week or so.