Hydrangeas thrive in wet weather, hence the name :-), and take in a lot of water through their petals. If you do grow them make sure you spray them with water as well as watering the soil.
They are one of my favourite flowers too.
Good luck!
FFx
I have fallen in love with mop head hydrangeas - can I grow a hydrangea bush on my balcony? If so, any pointers would be appreciated on where to purchase and planting techniques. TIA