Posted: 19/12/2015 at 10:59
Marie, definitely the watering. Take cuttings...they are easy...and when they have rooted well give your hydrangea to your mum. It deserves to be in the garden.
just because a hydrangea will grow in a pot it doesn't mean it should.
When you do grow on another plant from your cutting Marie make sure the compost is good....use john innes, it will hold water and nutrients much better. And never let it dry out.