I want to know how to prune lilac trees well? I want to know about the drip lines of trees and shrubs? How far? How to feed? Thank you for anny help you can give me.
regarding drip lines, here is an illustration done by the Morton arboretum as it was viewed during a tree excavation.
Notice most of the roots of the tree shown are just below the surface, where the air is. In environments where the atmosphere is very humid, such as tropical rainforests, many plants do not even grow in the ground at all. Fertilize after your soil has been sampled and analyzed. While this method is not entirely accurate, at least it provides some idea of what, if any, nutrient supplementation may be required for best plant response. Tall, old, twiggy lilacs - if healthy - can be made more vigorous- and productive-looking by whacking all of their stems down to 18"-24" above the ground. Otherwise, you may wish to occasionally cut out the oldest, least vigorous trunks, and leave the rest untouched.