Posted: 17/07/2016 at 20:29
Hmmm. Well, they look as though the head has just folded over from the picture, which would be lack of water pressure. Various obvious reasons for that which I'm sure you already know, but still:
is the soil over-dry, causing them to wilt? Is it soaking wet, so roots have rotted?
Less obvious, perhaps - have you checked all ties, so the stem isn't being cut into anywhere?
have you checked around the base of the stem for signs of slug damage? As with clematis, they can eat around the stem and kill it.