Eric , to answer your question, ...japanese bowyers look for old standing poles out in the bamboo woods.....so it hardens best whilst standing....they say this is much harder to find than the younger bamboo......but I notice that the longer I keep cut poles in my workshop the better they get too. You are lucky to be able to cut your own, I'm sure you know what your doing...big bamboo dont grow in the UK....it comes from china and there is such a demand for it, it is all cut young, once it reaches a good height..a lot of this stuff is quite soft....but does get better if you blast with heat in a heat box and keep it a few years