I'll take a wild-assed guess and say 1.25 inches. That is *IF* they never thirst for water *AND* there's lots of organic matter in or on top of the soil. And maybe just a tiny sprinkle of fertilizer while they're shooting and leafing out. Oh yeah... and a dead cow buried underneath. OK, the cow is optional. But the other conditions should boost next year's culm girth. It will also, by the way, cause your bamboo to spread like crazy.

Thanks it wont spread to far I dug a trench around it and poured concrete in it. Dont have a cow but will my neighbors dog work ok?