We had a 6 ft black bamboo which first seemed to die off then sent up massive shoots to about 12ft. This flourished for a year and then showed signs of water starvation and the leaves died. We lifted it out of its large (2ft diameter)pot and it is seriously root bound so much so that the roots cannot be separated. Some of the roots look like black bamboo themselves. We are re-potting it and adding sharp sand but are at a loss as to whether or how we could separate the roots, except with a power saw. Can anybody suggest a way we can save this beautiful plant. Thanks Rachel