12 lbs sweet ripe plums, rinsed
4½ cups white sugar
8 pint-sized jars with lids.
Place pitted and halved plums in to the mixing bowl & drizzle with 4½ cups of sugar. Stir plums until all coated with sugar. Let them sit for 1 hour than transfer the mixture in to a large cooking pot.
Bring it to a boil uncovered, stirring occasionally. Boil until mixture is bubbling uniformly. Simmer for 10 minutes than turn off the heat. Cool to room temperature.
Repeat step 2 total of FOUR times. Last time bringing it to a boil at the lower temperature, stir frequently to prevent scorching.
To Sterilize Your Jars:
Start by washing your jars and lids with warm water and soap then let them dry in the oven at 215 for about 20 min or until completely dry. Boil the lids 5 min.
Filling and processing your jam:
Transfer your boiling hot jam to the jars using a glass measuring cup and a funnel (least messy method) leaving about ½″ space.
Screw the lids on enough to keep a tight seal in place but don't over-tighten them since air bubbles need to be able to escape and place in the oven at 350˚F for 15 min. Carefully remove from oven (don't tighten the lid more or you might disturb the seal that has formed), flip upside down and let cool to room temperature.