AH! R-A-W bamboo!!! I was trying to figure out what you were talking about since there is nothing that I know of in the wold of bamboo called Rew!!!
You should never use green (grown this year) culms. Always use culms that are 2-3 years old -- standing mature culms, not standing dead culms.
In the groves I cut from, I mark the year that culms sprout, once they reach full height later that year. The don't grow an taller or larger in diameter after that first burst of growth.