Start with washing the fruit with cold water. Cut the peach and the plums in half and carefully take the pit out. (Keep the peaches halved, do not cut them into small pieces)
in a large pot add 3 cups of peaches, 1 cup of plums, 1 cup of sugar, and 1 gallon + 1 cup of water.
Bring the pot to a rolling boil, and continue to boil on medium high heat for 4 minutes. Watch it carefully so the doesn’t boil over.
While the homemade fruit juice is boiling, get your jars sanitized by placing them either in a boiling water bath canner or by washing it with warm soapy water then put the jar in the microwave for 2 minutes. Be careful the jars will be hot! use a towel to handle it. You can add the fruit juice solution in quart jars, liter jars, or in a gallon jar.
In a small pot, boil the canning lids for a few minutes as well. Once they are done boiling, take them out using thongs and lay them out to dry on a clean towel.
While the jars are still hot, lay a clean towel next to the stove and stand your jar on top of it. Once the juice is done boiling, using a large ladle pour the juice halfway into the jar then add in the fruit then fill the rest of the jar with the juice. ( The reason you should add half of the liquid at first into the jar first before adding the fruit in, is that it doesn’t hit the bottom of the jar directly and they don’t turn into mush)
leave an inch of headspace in the jar you are using. With a clean paper towel dipped in vinegar, wipe the jar rims then place lids on the jar and tighten the screw bands.
Using a towel turn the jar with homemade fruit juice over (always turn the jars away from your body) upside down on a towel. Place a plastic bag over the jar and then wrap a warm blanket over it. This is the old home-canning method that my grandmother used! It works every time! Now all you have to do is wait till the jars cool down completely, which will take about 6-8 hours to cool. And it is ready to Store for the winter!