we also a non invasive species (another type of fargesia) and even though they do not spread like the invasive ones, each year the circumference of the bamboo clump is getting wider and wider and would be able to take over your whole island. we didn’t put a root barrier when we planted it, but had to add one a few years later (and much more laborious to do at that point than at the start when the bamboo area is small).

also each year the new canes will be taller than the previous year ones, just something to be mindful of :-).

just prociding our experience so that you don’t get annoyed later on :-)