My Dad had planted these hydrangeas somewhat recently, and they were vibrant & beautiful. Now, not so much. Can anyone tell me why this happened, and what can be done to make them pretty again?

Hydrangea flowers change colors over times based on the soil pH levels. That's why you may have felt this.

Individual flowers do not last forever. The pictured flowers are just past their prime. New blooms will come in the future.

As a new plant, water often if/when it hasn't rained for a few days. Hydrangeas are thirsty plants. Next year and for the future beyond that, water in the morning if you see wilted leaves.

These look like they came from a garden center and possibly were forced into bloom. remove the spent flowers and give them time to settle in. I doubt more blooms will happen this year but next year they'll be lovely. Yes Tiffany is correct. Hydrangeas are thirsty shrubs. I've been dealing with a hedge of them on the north side of my house for over 16 years. late spring I prune them back to a healthy set of buds. Thats it plus water when rain has been scarce. They like rich loamy soil but manage to grow almost anywhere. No full sun please. Depending on the variety you have will tell you when to prune and good pruning is a must. By the fall all the dead flowers have been removed and I can nip and tuck the woody stems to keep the plant within size. Just don't take too much off. Good luck. Hydrangeas are a beautiful addition to any garden. BTW they make a good cut flower and some even dry nicely.

I would suggest posting this in the Hydrangea forum, resident expert Louis is very helpful. The answers here seem spot on though.

in greenhouses they're really pushed to look great when they come to market... so when they hit real life, it's a little shock- all kinds of hard things happen-

it's a beautiful bush that will live forever (i have a half dozen more than 40 years old). Plant it someplace shady this year, water well and it will pay off