hydrangea color

hi,
you need to give it aluminum sulfate. it usually comes in a clear plastic bag weighing about 2 pounds. apply it every 2 weeks. another problem people create with hydrangeas is they cut them back or prune them,
only prune out dead parts in the late spring . people cut the darn things back in the fall and no flowers is the price they pay. but you must be behaveing yourself with that, caus you get flowers. just that they need the aluminum sulfate...... good luck to you............sandy