Wild plums grow natively throughout the United States, and are used to make jams, jellies and other desserts. The sweet fruit is oval or round in shape, and smaller than the cultivated plums at about 1 inch in diameter. It is ready for harvesting and jelly making in early fall, usually around August or September. This recipe yields about 4 pints of wild plum jelly, and it makes a great way to use any excess wild plums from your garden or property.
Wash the wild plums well and remove stems, blossom remnants and any damaged areas of the fruit. Place the plums in a large stockpot, and add water until it's just below the top of the fruit.
Place the stockpot over medium-high heat and bring the water and plums to a boil. Reduce the heat to medium-low, and then simmer uncovered for about 15 minutes, or until the fruit is soft. Use a potato masher as the fruit is simmering to break the skins and separate the flesh from the pit.
Line a colander with a jelly bag or two layers of cheesecloth and place over a large bowl. Pour the cooked wild plums into the jelly bag or cheesecloth, and then allow them to sit overnight. The plum juice will drain through the filter into the bowl during this time.
Remove the colander the next day and discard the spent wild plums. Measure the juice in the bowl, and then transfer it to a medium-sized saucepan. Bring the plum juice to a boil over medium-high heat, and continue cooking for 3 to 4 minutes.
Add 3/4 cup granulated sugar for each cup of juice in the pan. Stir to combine and bring to a boil. Continue boiling, uncovered, until the mixture begins to turn to jelly, usually about 20 minutes.
Check the wild plum jelly for doneness by placing a cold spoon into the mixture. Lift it out, and if the liquid coats the back of the spoon, it's reached the jelly stage. If not, boil for an additional 1 to 2 minutes and check again.
Transfer the wild plum jelly into the sterilized canning jars, leaving about 1/4 inch of space at the top. Secure the lids in place and process the jars for 10 minutes in a boiling water bath. Remove the jars from the boiling water using metal tongs to avoid injury.
Places the jars of wild plum jelly onto clean towels to dry and seal. The lids will pop when the jars cool, indicating that they have sealed. Store in a cool, dry place indefinitely. If some of the jars do not seal properly, store in the refrigerator for up to 30 days.