There are a huge variety of juices in the grocery stores, but calling it juice (with all its infused toxins) is highly generous. Nothing beats the taste and safety of a freshly opened home canned juice. Then, all you need is to dilute with water to your preferred sweetness, add some canned plums into your glass of juice and enjoy!
Prepare the syrup. Add sugar into a medium pot with water and bring it to a boil stirring until sugar granules dissolve. After it boils remove from heat and set aside.
Pack plums into a jar as compactly as possible. Fill jars with cooled to warm syrup.
Place 3 or 4 jars into Stove Top Waterbath Canner pot (depends on a size of you canner), fill the pot with cold water until the jars are submerged 3/4 in the water.
Bring the water in the canning pot to a boil (when the water in the canning pot will start boiling you will also see the bubbles floating from the bottom to the top in jars, this means that the water in jars is boiling as well).
Let the water in the canning pot boil for about 10 minutes. Then screw the lids with bare hands as tight as you can (this way you will feel if the lid screwed properly not sideways, be careful not to burn your hands). Then put on canning gloves or use canning utensil to remove the jar from the pot. Screw the lid tight. After the lid is screwed tight, flip a jar upside down and let it stand until cools (I leave them in this position overnight).
Drain the water from the canning pot and repeat the same instructions with the remaining jars of plums.