supposedly if you add amoninum sulfate to the soil, it will make the PH more acidic and therefore give you blue hydrangeas. However, I used it on a Nikko Blue and it became washed out.

I do have a Europa Hydrangea and it is a lovely blue purple. This is a good source.

http://www.hydrangeasplus.com/home.php?cat=35

Are you near Atlanta? If so, go to one of the nurseries that has a lot of hydrangeas during June, like Wilkerson Mill or Habersham, and see what you like best (remember to think about size, too - some of them are much bigger than others).

I am sure there are nurseries with BIG selections in other parts of the state - these are the 2 I know.

I don't think you can do it all by changing soil acidity - try to start with a plant you like.

Five years ago I bought a beautiful rosy pink hydrangea at Kroger's. It didn't have a name, but I looked it up and decided it was perhaps a Pia or Forever Pink. I meant to take it to a friend in the hospital but I loved the color and decided to keep it and take something else instead. Each year I repotted it into bigger clay pots as it got bigger, and it always bloomed pink. Finally last fall I planted it in the ground, and this year it bloomed the most beautiful dark purple-ey blue. I really hope it stays that color as I like it better than the pink. I put nothing in the soil except compost when I planted it. So maybe that's the way to get the dark blue color.