Ah, well you'll have to unplant them if they're spreaders - you need a solid barrier around each plant to a depth of 18 inches minimum vertically, and as wide as you want the plant to spread, and then plant in the centre of that. You can buy root rhizome barrier for this purpose over the internet, or some people use a small dustbin and cut the bottom off, anything like that.

In case you're not used to imperial measurements, Bamboo means is that you'll have to dig the bamboo plants up and put a solid barrier at least 45cm deep - or deeper would be better - around each plant.

Well done Beattie - trouble is, I still think in feet and inches, I've now got a tape measure permanently on my desk here to check what people mean when they say, for instance, 90 cm.... I'm alright with metres, just about, but smaller divisions fox me every time.

as it goes i put my barrier at the right depth round my already growing bamboo and its fine . i guess it depends on how much bigger you actualy want your bamboo to be .