Place all of the ingredients into a large saucepan. Turn the heat on medium and stir occasionally.
Let the rhubarb and strawberries cook down I let my jam cook down for 1 hour and 20 minutes. Smash the strawberries a bit with the back of your spoon against the sides of the saucepan.
Once the jam thickens and the fruit is cooked to your liking, you'll need 3 pint jars. The way I test my jam is by placing a plate in the freezer for 10-15 minutes and then putting a dollop of jam onto the chilled plate. If it sets up, it's ready to be canned. If it runs, cook it for a while longer.
Once the jam is ready, place it into hot sterilized jars. Clean the rim with a damp towel. Place a hot lid and ring onto the jar. Place the jars in the hot water canner and make sure the water covers the lids of the jars. Once the water comes up to a boil, boil for 10 minutes. Remove from the hot water canner and place under a warm towel. Let sit overnight.