Plum Jam

We have two plum trees so we've gotten really good at making plum jam. Today, we made 50 jars.
Start with fresh plums right off the tree.

We had a good crop this year.

Each batch of jam makes 10 cups and uses 4 pounds of plums which is approximately 6 - 8 cups or 40 medium plums.  I always weigh them just to be sure.  It can vary quite a bit.

Wash plums and pit them but do not peel them.  I cut them in half and put them in the food processor.

Chop finely in the food processor using short pulses, do not puree.  Keep some chucks since jam ought to have little pieces of fruit in it.  Pour into a 6 or 8 quart pan and add 1/2 cup of water per batch, 1 box of powdered fruit pectin and 1/2 tsp. of butter to reduce foaming, if desired.  Stir constantly, covered for about 5 minutes until mixture reaches a full rolling boil that cannot be stirred down.  Skim off any foam off the top.

Add 8 cups of sugar, return to a boil and boil for 1 minute.  Remove from heat.  Fill prepared, hot jars leaving 1/4 inch of head space.

To prepare jars, run through the dishwasher to sterilize.  To prepare lids and caps, put in a pan, cover with water and bring to a boil to sterilize.  Keep them hot until you are ready to use them.

When jars are filled with jam mixture, wipe off the mouth of the jars with a clean, damp cloth.  Put on the hot lids and caps and put into the canner to be processed.

Process for 15 minutes with boiling water that covers the jars.  If you live in an elevation between 1,000-3,000 feet, add an additional 5 minutes.  If 3,001 - 6.000 feet, add an additional 10 minutes.  If 6,001 - 8,000 feet, add an additional 15 minutes, and if  8,001 - 10,000 feet, add an additional 20 minutes.

At the end of the processing time, carefully remove the jars from the canner using tongs and allow them to cool.

You will hear the jars seal as they cool as they make a popping sound.  Listen for the sound and be sure that they all seal.  Another way to check the seal is, after they have cooled a little, you can press on the top of the lid and it should be slightly concave.  It should stay that way when pressed.  If you have one or more jars that do not seal, remove the bands and lids, wipe the mouth of the jar with a damp cloth, and put on a new lid (one that has been in hot water) and cap and return to the canner to be re-processed for another 10 minutes.  (I've never had to do this, it doesn't happen very often)

Enjoy your delicious plum jam and give a few jars away as holiday gifts this year!