8 cups black plum chunks*
4 1/2-5 cups sugar
1 box powdered pectin
1/4 cup lemon juice
zest from two lemons
Prep jars/lids for canning. Place the plums into a large, heavy bottomed pan. Add the sugar, lemon juice and zest. Bring to a boil, stirring and breaking up any big chunks (I used a potato masher) until it begins to reduce and thicken. Stir in the pectin. Continue cooking at a low (rolling) boil for 2-3 minutes or until it looks jammy. Fill the jars leaving 1/4 inch headroom. Process in the hot water bath for 10 minutes.
Yield: 6-7 8-oz jars.
*I started off with about 2 lbs of whole plums.
Note: A great source for canning information is the Blue Book guide to preserving. I highly recommend it for learning how to can. Here is a bunch of other canning books and equipment I find useful.