Fill your canning pot 2/3 with water and put on the stove to bring to a boil (I used a large stock pot for this much jam).
Put berries, sugar and lemon zest/juice in a large pot and cook over medium high heat for about fifteen minutes. You want to really boil the fruit down so that they begin to look syrup-y. If you have an immersion blender, use it at this point to puree some of the fruit. If you don’t, use a blender to puree about half the jam (working in batches, you don’t want hot jam to splash you).
Add the blended jam back to the whole fruit jam. Bring to a boil and squeeze in the pectin. At this point, there will be a bunch of foam on top of the jam. Skim the foam with a large spoon. Let boil for approximately ten minutes more, until the jam looks very syrup-y (when boiling, it should resemble boiling candy).
Lay out your clean jars, you’ll need approximately five pints or 10 half pint jars. Put your lids in a saucepan of hot water in order to soften the sealing compound. Bring a kettle to a boil now as well, in case you need a bit more boiling water for your canning pot.
Fill the jars. Wipe the rims with the edge of a towel dipped in boiling water. Top with lids and screw on rings. Put a rack or folded towel into the bottom of your canning pot (you don’t want the jars to be in direct contact with the bottom of your pot). Carefully lower the jars into the boiling water. You can stack them one on top of the other if need be.
Process for ten minutes in the boiling water. When time is up, remove the jars from the water and put them on a towel on the counter. They should begin to ping fairly quickly, indicated that they’re sealed. If any of your jars don’t seal, make sure to refrigerate them.