I have lovely hydrangea plants but no flowers ...!

Are you fertilizing it? Maybe too much nitrogen in your fertilizer. Nitrogen makes the plant green and leafy but it you get too much it will only grow the green stuff. So maybe back off and not fertilize so often or dilute it a little more or look for a fertilizer that has less nitrogen (which is the first number on the label ie 10-10-10 or 10-0-0.)

Hopefully this will help solve your problem

http://www.southernliving.com/garden/grumpy-gardener/why-your-hydrangea-didnt-bloom

Too much sun, maybe? A lot of woody stalks? Prune after they bloom and cut back dead wood. Do not trim before the bloom, even if it looks shaggy. Don't cut back in the fall, you will have nothing. Fertilize, Coffee Grounds worked for my Mom. You could ask your local extension for any advice, or a good nursery in your area may have better advice to offer.

Super phospate in middle of august in south.

Do not cut the bush back until it blooms.

https://thistlewoodfarms.com/how-to-make-your-hydrangeas-bloom/

https://www.gardenguides.com/84033-make-hydrangeas-bloom.html

http://www.millionplants.com/advice/wont-hydrangea-bloom/

https://www.thisoldhouse.com/ideas/5-tips-growing-gorgeous-hydrangeas