Combine rhubarb, strawberries, peaches, blackberries, blueberries, apples, and sugar in a saucepan over medium heat. Bring to a boil. Boil for 10 minutes, stirring the whole time.

Add pectin to the saucepan and boil until jam coats the back of a metal spoon, about 10 minutes more. Remove from heat and transfer jam to sterilized 8-ounce canning jars and cover with new lids and rings.

Place a rack in the bottom of a large stockpot and fill halfway with water. Bring to a boil and lower jars 2 inches apart into the boiling water using a holder. Pour in more boiling water to cover jars by at least 1 inch. Bring to a rolling boil, cover, and process for 10 minutes.

Remove the jars from the stockpot and let rest, several inches apart, for 12 to 24 hours. Press the center of each lid with a finger to ensure the lid does not move up or down. Remove the rings for storage and store in a cool, dark area.