Some of these plants are not hardy, but it's worth giving it a try. I'd re-pot it, into a container that's a couple of inches bigger around than what it's in. Then I'd keep it in a cool spot, out of direct sun, and keep it somewhat dry. It's too late to get it to go completely dormant, but you want it to take a little rest anyway.

The bigger pot and the partial shade should make it easier to stop watering it daily.

You might find more info on the hydrangea forum.

Same thing happened to me about 6 years ago when someone from Manhattan brought me a hydrangea as a hostess gift.

Are there any markings or tags on the plant to identify the grower? I ask because I found one on the florist's tag and called the company that grew the plant. They told me its name (which I've forgotten) and that it would not be hardy in my climate but I decided to give it a try. I kept it in a cool spot (no direct sun or heat) until spring.

Then I put the plant outside under a bush for several weeks to get it adjusted to the great outdoors. I planting it in a sheltered area on the side of the house where it was protected from winds. That tiny plant is now about 4 feet tall and just as wide. It's a blooming machine. So you never know.

DtD gave you great advice about slowing it down and getting it ready for the outdoors.

Molie

Thank you to the both of you! I would love to have it in my yard, so I'll follow your direction.
Your info is much appreciated!