Coffee grounds have most of the acid removed during boiling so you are not adding much. That is why you can safely add coffee ground around acid-hating plants like lilacs. Starbucks used to state that in the trash cans where they leave coffee grounds but I have not checked lately.

As for changing the color, it is a multi-year process that requires acidifying the soil and adding aluminum for the life of the plant. Many people who do not have azaleas/rhodies nearby will utilize aluminum sulphate. Achieving the proper hue of blue will be difficult and will take several years. Many people prefer to do this on container grown plants because they find the process easier with them.

Please read the detailed information on the link below.

Luis

Here is a link that might be useful: Hydrangea Color Change

THANK YOU! What a great website! My ES is in a container, so I'm hoping that I will be able to fiddle with the color somewhat.

Actually, while I was picking my plant out, an older couple walked by and the husband asked the wife, "Wouldn't one of those look nice in our yard?" Her reply *grin* "Oh no dear, those are the blue ones." =D Thanks again for the very imformative answer!