Why is my photinia red robin so sad?

over the past couple of months, she's looked more and more depressed. This morning, I decided it was time to cut her back, but the stems are still green under the surface, and the buds still look viable (just).

What could be wrong with her? The other two in the garden are showing their lovely new red leaves (in a different area), as are all of the other specimens in the neighbourhood.

The only thing that has changed is we had the patio replaced, but that was this time last year. Maybe the water is running in a different direction now?

 

How dry is it? I know Photinias, coming from New Zealand (North Island), like a steadyish, mild, fairly humid climate (though they're hardy in western Europe).. but frost can damage them but in reality it would have to be a pretty heavy frost and I don't think your winter was that cold this year though? How dry is it? If it's dry it may be sulking.

Otherwise it could be some type of disease or virus.

The other option I think is possible but unlikely.. some plants droop leaves before flowering, particularly in the ericaceous family.. but I don't think this is the reason, given Photinia have compound flowers

 

Drought would make sense.

The patio had to be replaced, as we needed to sort out the roof drainage.... The whole house failed to go down one broken drainpipe, just next to that photina. So there would have been a lot of splash and runoff (the wall at that corner was permenantly damp). We now have three other working downpipes, and the water goes into the underwater rain tank properly.

It has also been quite dry for a long time, so the rain tank will not have been overflowing (just below the plant)

 

I was looking at the photo of yours as mine is also looking very unhappy But mine is due to a fairly cold winter rather than drought. My Photina is ancient (at least 50 years old) and I have thought it has died a couple of times since living here but it struggles on! I think the breeders may have produced a hardier variety nowadays? as there are plenty other Photinias close to where I live which don't seem to be affected like mine is.Currently every leaf on mine is chestnut brown and will fall off. I will prune it back about a ft all round in a week or so and it should recover. Hope yours does too.