Making blackberry jam, or any jam, is about the easiest canning project there is.
Step 1. Cook down 7 quarts of blackberries.
Step 2. When berries come a boil, add 2 packets of liquid pectin.
Step 3. Bring it back to a boil and add 7 cups of sugar. We use Turbinado (raw sugar).
Bring just to a boil, skim off the top and pour into jars leaving 1/2 inch headspace.
Wipe off rims of jars and put the lids on.
Bring water to a boil in the canner, insert jars and add more hot water if necessary to cover jars by at least 1 to 2 inches. Bring water back to a boil before timing. Time 5 minutes for pints and 10 minutes for quarts.
To remove seeds from blackberries, put your berries through a food mill before cooking them down.
Most jam recipes recommend that you do not make big batches at a time because they may not set. I have been successful with this large recipe so far. It makes about 14 pints. In this case I didn't have 14 pint jars available so there are some quarts and 1/2 pint jelly jars included too. Talk about delicious!! We have blackberry jam from the garden to enjoy till next years harvest with lots to share!!