I don't think I have to worry about reseeding in my neighbour's lawn and garden. She's retired and outside almost every day so something starting from
seed doesn't stand a chance in her yard.
It's definitely underground runners -- they are popping up in my garden too, but I'm yet annoyed enough with it to remove the whole
plant. I'm only now taking control of the gardens I inherrited 3 years ago with the house, so I'm not ready to remove anything that's not a
weed. Just removing the
weeds and pruning back unruly bushes has left enough 'empty canvases' for next year that I really don't need to create any more just yet.
Would even cutting any underground runners at the fence line make any difference, or would the runners that have already made their way onto her side be enough to support the
plant still popping up on her side? I'm willing to excavate and try to cut the runners heading to her side if it will make a difference, but I'm wondering if there's even a point in that.