The only advice I have is when you blanch your tomatoes to remove the skin do it for only 10 to maybe 20 seconds at most in rolling boiling water and cool them in an ice bath right away. The skin will slip right off.
Add a little lime juice to the jars you use for canning and you will be successful. they should keep for years.
Go for growing more tomatoes!
Do you measure out the lime juice for each jar? How much per jar? Thanks for the tip!
I use Heinz variety plum tomatoes that I buy from Territorial Seed Co and the plants ALWAYS produce phenomenally well.
I tried another variety this year as well, just to compare, and they aren’t doing spit.