Bit of a dilemma here, and this is a long post, so please bear with me. I am casually friendly with next door neighbours, and this issue concerns them.
Two years ago, my BIL very kindly offered to seal my garden fence with a water resistant sealant that protects/prolongs the life of the fence by a great deal. He sprayed the sealant on both sides of the fence. Neither of us realised until later that the sealant had sprayed through the openings between individual wooden boards, and onto the plants my neighbour has along the fence. Some of the plants turned brown (didn't die), but as it was the end of the summer it seemed not a big deal. She commented on it, and I apologised, but that seemed the end of that.
It is time for the fence to be sealed again. The neighbour's dh bid for the job (he's got a house painting business), but I found someone who bid the job for about 1/3 of the neighbour's dh. The neighbour's dh knows, and seemed fine about it. We even joked that we'd do our best to protect the plants this time.
I explained to the fellow doing the job that he needed to protect my plants/trees (and hers) while sealing the fence. He devised a system of draping plastic sheeting on the fence so spray would not go through the boards onto the plants. He also covered some plants to protect them.
The neighbour's dw was outside today - and fussing/worried when the men were doing the work. They tried to be careful, but it seems that some of the sealant has gotten on her ivy (ground cover). As they were doing the work, the men offered to replace the ivy if there was a problem, but she was not very receptive. When the men were finished (and she was out), they rinsed the ivy twice with fresh water in an attempt to wash away the sealant that is on the leaves.
I've now been out to look, and I would guess that the ivy is going to turn brown due to the sealant. I honestly don't know what more the men could have done to be avoid this happening.
Long winded, I know, but I don't want a problem to develop. On one hand I think it's not a big deal because it is 'just' ivy (not stuff that has been there for years), but she is a gardener and takes pride in her plants.
What would you do?