I planted a large bamboo in my garden last year. There are new leaves that started to grow last year but they stopped developing and are not full size. Most of them seem to be shriveling to an extent. Could the plant need a nitrogen feed?
Ernie 2 - my two bamboo mostly just have last years leaves on them just now - they really kick off with new foliage around May to June and the rest of the summer. It may just be the normal timing for yours not to produce more leaves just yet. I get so much leafy foliage in the summer that I cut a lot of it back to see the lovely bamboo stems - but the stems have grown thicker over the years to look like true bamboo as we imagine it. All takes time. But I don't expect foliage to really start kicking off for about another month.
So what about feeding them with, say, nitrogen to green them up?