I have had 2 Back Bamboo in very large pots for 3 years. After our awful winter I wasnt sure if the had survived. ( I am almost certain that I have lost 2 Olive trees). However, There are new lovely green shoots coming through at the base of both Bamboo. Now, do I cut the whole thing back to the new growth or leave well alone. The existing leaves have brown tips and a lot of bare twigs....Do I cut off back to the main branch ?