My hydrangea bush is looking sad.

You should deadhead or cut off the blooms as soon as they start to die. I'd go ahead and do that now. They are blocking the sun from their leaves. So that's why its probably looking sad. Also, a nice watering helps too preferably in the morning.

When the flowers have died it needs to be pruned. Cut back to the first two buds on each stem. Give it some fertiliser and a good drink of water. That should do the trick.

No, don’t cut it back until you know what type it is. Some hydrangeas produce next year’s blooms on this year’s wood (referred to as “old wood”) so if you trim it back, you might be cutting off the blooms for 2018. Other hydrangeas produce blooms on new growth next Spring so this is referred to as “new wood”. If you have that type of hydrangea, then you can cut back this Fall. Go on Google, first, and see if you can determine what type you have. Good luck!

I typed a lengthy reply to you ... but don't see it yet. It might crop up in a bit. In the meantime, please don’t cut your hydrangea back! You may be cutting off next year’s blooms!

Some hydrangeas produce next year’s blooms on “old wood” ...in other words, this year’s branches. So if you cut your hydrangea back, you might be removing next year’s blooms!

Some hydrangea produce blooms on “new wood” .... the branches that grow next Spring. Google the different species and try to determine what type of hydrangea you have - whether it’s mop-head, lace-cap, oak leaf, etc. then you’ll be sure to not cut off next year’s blooms.

Do not cut it back that will lead to no blooms next year.https://www.thespruce.com/when-to-prune-hydrangeas-1403320 Next season ,before the new growth emerges you will feed it based on what type it is.Until then leave it be

Hydrangeas need to be cut back as soon as the bloom is finished. They also do not like nitrogen such as from grass clippings. They need calcium and potassium. I combine banana peels, egg shells, and used coffee grounds in a blender with a little water and feed it at the base of the hydrangea. Hope this helps

The flower heads could be cut off but not too far down in case you get a really bad winter - which will take the plant down some anyway.

Thank you.

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