In a large, non-reactive pot (stainless steel is best) cover the rhubarb with water. Fill the pot, no more than 3 inches from the top.
Simmer over medium heat until the rhubarb has cooked completely and softened. The juice should be a nice pink color. Drain to yield the juice. The approximate volume will be about one gallon.
Return the juice to the pot and the stove top. Sweeten to taste with maple syrup, honey or sugar, approximately 1 cup. If desired, simmer the juice with cinnamon sticks or whole cloves.
Heat the juice to 190 degrees and cook for 5 minutes. Do not let boil.
Ladle the juice into sterilized quart jars. To make a shelf-stable product, process the quarts for 10 minutes in a boiling water bath.