Posted: 08/07/2016 at 22:12
Hi Tim - a couple of questions. How big is the container it's in? Have you had a look at the root system?
If it's been in the pot for over a year, and the pot isn't sizeable, then there's a good chance that the pot is full of roots and not much else, which means there isn't much to sustain it. Watering and feeding won't really help if that's the case. Any plant in a container for a long time needs a reasonable amount of soil to thrive.
Ironically, although many bamboos have a reputation for being invasive in the ground, they often don't do well in pots long term.