A number of years ago (too many to remember) we planted a pot of Giant Bamboo and one of Black Bamboo. Over the following years we watched these plants grow very very slowly and never saw them do much in the way of spreading. The folks at the nursery told us "Just wait! When they take off they REALLY take off!". Several years ago they finally managed to spread over the entire area we planted them in and I actually had to cut a number of them down since they were by then in the power lines. Imagine our surprise this spring when we went to the back side of the area near the creek and found THESE monsters breaking through the ground. This is one of this years Giant Bamboo plants and as you can tell from the picture, its a big one! We measured the circumference and it was slightly over 9.75 INCHES and well over 7 feet tall ....and it's only been out of the ground for a couple weeks! I can't imagine how big these are going to get if the weather continues the way it has.