Posted: 29/11/2013 at 16:14
I agree with blairs that vine weevils are not esp a problem with houttynias. And they do, indeed, like water (houttynias I mean)
Could,there be a,human pest doing the rounds there? Weedkiller perhaps?
Are,plants actually growimg in the garden dying off too DonnainSussex
Since your neighbour's plants are,dying too I think foul play is possible.
Is it possible you are using a watering can that has been used for weedkiller? Even the tiniest amount of weedkiller remaining in the can can cause problems.