The other day I was in a nursery and saw Hydrangea paniculata 'Limelight' for sale. Most of the three gallon plants looked like this picture (taken at my church). But there was one plant that had obviously come in from another state (Oregon, maybe?) that had mint green blooms. 'Limelight' is a great plant - fast growing and easy. It's excellent for cutting, and in the fall, the blooms fade to mottled pink and green - really outstanding for fall arrangements.
But back to the mint green. For some odd reason, the very first picture I ever saw of 'Limelight' (before the digital camera age; it was a bouquet; someone sent it to me from a wholesaler who first distributed it in the U.S.A.) showed the flowers as mint green. So, when I began seeing 'Limelight' around, I thought it just didn't respond correctly to the heat in Atlanta.
Actually, the blooms are supposed to be lime green like the name says (I'm still not sure what the mint was all about), but they quickly turn white in the Atlanta area. I'm betting in places with cooler nights, the color holds better. I need to check with people in Highlands, N.C., (where paniculatas grow like crazy) to see if they stay lime green longer there.
This is one of those plants that everyone should have, just because it's almost foolproof. I say almost because the deer love it. They've chomped off my blooms time and time again.
So, if you have a spot in the sun and can keep deer away, you can have quite a show in July (in the Atlanta area) and in August up north.