Hi, welcome to GoY, are you sure this is a climbing Hydrangea, I've never seen 1 with leaves like these, it looks more like a species of elaeagnus to me, which is susceptible to coral spot, a fungal disease, spray with fungicide, Derek.

Doesn't look like a climbing hydrangea to me either

Hi Derek,

thanks for your tip. It's a Hydrangea Seamanii. I wasn't sure if it was lacking nuitrition? I've never used a fungicide, is there a recommended brand?

Thanks again, Andrew

I think yours is short of nutrients.
Andrewr has one of these why not put Hydrangea Seamanii in the search engine (up on the right) and you will find 2 photos of his very healthy one in flower in 2012 and 2014, and you can send him a message about yours.

Is this plant in a pot or in the ground?

It was bought in a pot and has now been growing for three years against a west facing wall in rich soil.It gets the sun from midday. It's full of new shoots and growing strongly. I've dug in some bonemeal to give it a boost but would dearly like to get the leaves to look more healthy.

Thanks for your comment.

Andrew

Hi, any general purpose fungicide from a garden centre, or some hardware shops will do, if you want a more eco friendly 1, try mixing 2 tablespoons of apple cider vinegar, with 1 gallon of water, and put it in a sprayer, cover the leaves on the top and bottom surfaces, but this is only a mild fungicide, if it doesn't work, just use a commercial product, Derek.

Thanks Derek, I'll let you know how I get on. Andrew