I love the greenhouse-forced hydrangeas we're seeing now. However, being from the greenhouse, they're not as hardy as those from the garden centers.
I've had good luck transplanting them to my yard, but I do baby them a bit. After the first blooms fade, I transplant them into a large enough pot so their roots have room to stretch. The pot goes into a shady outdoors spot where I can give it lots of water. By this fall or next spring the new roots will be established enough to plant into a shady or semi-shady spot in the ground. Hydrangeas are thirsty plants, so be sure to give them plenty of water during their first years in the garden.