Canning Tomatoes

Washing those tomatoes!
Washing those tomatoes!


Tomatoes in a jar.  That’s all they are.  But when it’s time to make sauce, every one of those jars is liquid sunshine.

So every September, people gather in their backyards and garages for the tomato canning ritual, armed with paring knives, aprons, more jars than you can count and ridiculously long wooden spoons.

Me and a very big wooden spoon
Me and a very big wooden spoon

This year, the annual canning weekend took place in August after a hot and dry summer, producing small, but sweet tomatoes. Usually, I can Roma tomatoes but this year, it was two lovely bushels of San Marzano.

Bushels of San Marzano tomatoes
Bushels of San Marzano tomatoes

San Marzano tomatoes are practically mythic in the cooking world. They are considered among the best tomatoes because they are low acidity, sweet, long and slim and have fewer seed pockets. They are highly regulated in Italy and are grown in certain soil, harvested only when perfectly ripe and have a D.O.P. label. (Denominazione d’ Origine Protetta, or D.O.P.). The San Marzano tomatoes I used were definitely NOT grown in the volcanic soil of Vesuvius.

Sliced San Marzanos
Sliced San Marzanos

They really shine when used in a barely cooked tomato sauce, where their flavour is paramount. I’m unsure how much of a difference I will notice in making sauce between the San Marzano tomatoes and Roma tomatoes, but there’s only one way to find out.

The process is pretty simple, just time-consuming. Everyone has their own way of doing it. When I was a child, my parents would grind the tomatoes by hand and when the jars were filled, I would stand outside in the backyard around this gigantic cauldron rumbling with boiling water, the filled jars boiled to sealing. I’m not sure what my job was, except to watch and make sure nothing else caught on fire?  No idea.

Anyway, no cauldron this time around. But there were many paring knives, aprons, sources of open flame and of course, the motorized tomato grinder. Until last year, we were also grinding the tomatoes by hand.  Here you’ll see me looking exuberant. Meanwhile, my arms were about to fall off.

Hard work but fun work.
Hard work but fun work.

Last year, in the middle of a sea of bushels of tomatoes, friends splurged and bought a motorized grinder. True godsend! If you plan on canning tomatoes and you have more than one bushel to do, buy the machine. Yup, you’re welcome, happy to help!

Here’s your RTI:


It’s all fun and games until you end up with 2nd degree burns somewhere. Happened to my friend. Forearm. True story. He was valiantly protecting a child who was about to have skin meet boiling crushed tomato. The friend has since recovered and children have been banned from the kitchen while canning.

Heat resistant gloves are a must, if you’re pouring the hot tomatoes into the jars or turning them over. I managed to get away with only two large blisters on my fingers from scalding them with boiling tomato.


  • Motorized tomato grinder
  • Buckets for your tomatoes
  • Paring knives (and lots of friends willing to de-stem the tomatoes)
  • Gloves, in case your hands are sensitive to the tomato acid
  • Pots to capture the crushed tomato
  • Jars and lids and rings
  • Magnetic lid lifter
  • Pot to heat the lids
  • Glass measuring cup of some kind to transfer the hot boiling tomatoes to your jars
  • Funnel to help in transfer of boiling crushed tomatoes to jars
  • Heat resistant gloves and oven mitts
  • Canning tongs to lift the hot jars, if needed
  • Space.  Lots of space, as you will need a place to rest the jars for at least 24 hours


  • Tomatoes
  • Basil or other herb combination

Here’s your “How”:

  • Wash and clean your jars
  • Wash the tomatoes
  • De-stem the tomatoes to remove any hard core and cut the tomatoes in half to make them easier to feed into your grinder
  • Grind the tomatoes
  • Put them on a heat source to boil them down.  How much you boil them down is up to you.  The more you boil, the more condensed the tomatoes become and the fewer jars you need to fill.  That means when you do use them to make sauce etc, there will be less cooking time in the prep.
  • While your tomatoes are boiling, make sure to properly heat your glass jars.  They can be heated in the dishwasher by putting them through a wash or steam cycle or you can put them in the sink and begin to fill with hot water.  You can add hot water from a kettle as you go to keep the sink water very warm.
  • Wash your basil and separate the leaves from the stem
  • Warm your lids in a pot of hot water
  • Place a leaf or more of basil (or other herbs) in each jar
  • Place your warm jar beside the stove, use your glass measuring cup to gradually fill up the jar, then use the magnetic lid lifter to pull a warm lid from your pot of warm water and place on top, then place the ring on top and screw on until you feel resistance, then make a 1/4 turn back.  Then carefully take the jar, turn it upside down and place it on a surface where it can rest for 24 hours.
  • This process skips what is often the last step in canning, which is then boiling the filled jars in water for 10-15 minutes.  I’ve had no major problems so far with skipping the step.
  • Hopefully, all your jars will seal properly.  You’ll be able to tell because the lid on top will look slightly indented or concave if it’s sealed.  You can, after 24 hours, press lightly on the lid to see if it’s sealed. If it pops up at all, you have no seal.


And when all the canning was done, we had a drink (or more) and a lovely dinner with homemade gnocchi and homemade sauce.



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