Cotoneaster hedge is thin
My cotoneaster hedge is about 30 years old. It has always been trimmed into a box hedge shape. I would like to trim it so it isn't quite so tall or wide; but the leaves always have only been on the outer tips of the branches. If I were to drastically cut back the branches, I'd end up with a bare bush. My questions are: why do the bushes only have leaves on the outer tips of the branches? If this reflects a problem; what do I do about it? Fertilizer? If it is normal for a cotoneaster bush to just have an outer covering of leaves, can I trim the hedge back to make the it several inches shorter, and also narrower? How do I proceed?
Albany County Wyoming
The reason the hedge only has foliage on the outer edges is mostly because of low light in the center of the hedge. The only way to get more light, and potentially more foliage, in the center of the hedge would be to selectively prune out some of the interior wood.
Hedges should always be pruned so they are wider at the base than at the top, in order to allow the most light to penetrate. Since hedges are typically pruned with what we call "heading" cuts, they develop very dense branching. This eventually leads to very little light reaching the centers of the plants resulting in little to no foliage.
There is a very good publication on pruning here: http://extension.psu.edu/publications/agrs-095. Look on page 20, Specialty Pruning, for info on hedges.
Let us know if you have more questions!