I'm in the process of cutting back a very mature and woody lavender. It was not pruned last year, and possibly not the year before that. It is about one metre and a half wide... I need it to be more compact. How much can I take off the sides without killing it? Will it regain green growth on those parts in the summer? Thanks!- K, Victoria, BC ..I hope this is in the right forum. I did some research online about this.. but it was not really adressed in the case of mature plants.