How long's it been planted there? If its less than two years, could be dry at the roots.

That was my thought too Bamboo. Is it in the ground or in a container?

yes, planted last autumn. I have been watering but maybe not enough. Thanks

I replanted it into a hole twice the size of the container which I then filled with ericatious compost. Thanks for your advice.

Could it be vine weevil perhaps....?

Gosh..that has just collapsed hasn't it. How sad. I fear if you've been watering it, it may well be that the dreaded weevil grubs have eaten the roots. They are a pest, especially. In potted specimens. The only way to find out is dig it out and look for them horrid little white grubs with light brown heads. If they have eaten the roots it will be obvious. What a shame :( the only effective treatment is a nematode that you water in. That and squishing the little .........s!

My thoughts exactly Cottagekaren ;) It looks like it was a healthy plant, well established with loads of flowers.....so I would say it's been watered and well cared for. Those pesky vine weevil have a lot to answer for....!!

The tragedy is by the time you see the evidence its too late. Whenever I see an adult weevil I get the nematode and drench everything in a pot.

I would just increase watering, and order a nematode treatment if you think it might be vine weevil, although I'm not seeing any evidence of weevil damage on the leaves themselves, and it is now in the ground, not in a pot. If you planted last autumn, this plant will require watering with a whole can of water, poured around the base of the plant, every 3 days when the weather is dry, or at least, we're only getting a few spits and spats of rain. If you're not sure, dig up the root ball, carefully, and examine it - if its dry, you'll know that is the problem. Leave the hose trickling at the base now for an hour or so, as an immediate rescue attempt, if you don't want to risk digging it up. If its any comfort, most of the leaves look fine - first signs of drought would be the flowers collapsing or buds drying up.

Once its been in two years, it should have sufficient water seeking roots to find its own supply, unless we're in drought for 3 months.

My thought would be too dry. If it's vine weevils I would expect the plant to rock about easily as the roots would have been eaten away. Plus I've neven know vw's to cause such damage to such a large plant. I recon it needs watering - empty an entire watering can onto it each evening (sprinkling a bit on the leaves isn't going to cut the mustard). You shoudl be able to tell if the rootball is dry simply by sticking your hand down there - don't think you need to dig the whole thing out! Is it in full sun? They prefer dappled shade.