Hi, I have a large bag of aluminium sulfate that I would like to use to turn my hydrangeas blue but there are no instructions on the pack, can anyone tell me how much I need (mixed with water)I usually sprinkle about 1/4 cup around the base of the plant and water it in. This must be done before flowers appear.Si es tu profesora l. a. que te corrigio el blunders, sabe, quedate tranquila. El aluminio tiene número de oxidación +3 y el radical sulfato -2, intercambiando número de oxidación por atomicidad, para equilibrar, te queda lo que dijo tu profesora...Other related question