If you want to find some ways to prevent your bamboos from spreading I have a couple of ways to fix that. If you have any narrow corners of your town you should use those tight spots to put your bamboos, than you may use trees, tree stumps, bamboo stumps or a small PWP to block the shoots from growing out of the zone. I am suggesting things that will look neat and tidy because who wants random splots of designs making your grass look ugly right? lol anyways I hope this advice helps.