Saturday, April 3, 2010

Bushwhacking! Proper Shrub Pruning by M J Lechner

Early spring is a good time to sharpen those pruners and get busy thinning and shaping the shrubs and bushes on your property. 

The first thing to consider is whether or not  blooms form on old branches or on new wood.  Forsythia, lilacs and hydrangea all bloom on last year’s growth, so they should be left alone until after they flower.  Hibiscus, many clematis and buddleias (butterfly bushes) bloom on fresh growth, so they can be thinned and shaped before the bloom season. 

There are two ways to approach pruning your shrubs: one is to thin and the other is to regenerate the entire plant.  Thinning is the less drastic approach.
Remove all the dead, diseased and weak (thin-diameter) branches.
Remove all the crossing, rubbing branches and those that lay on the ground.
Remove some of the larger stems (10-50%) from the older branches.
Selectively shorten and thin the remaining stems.
Remove some of the new sucker growth

Regenerative pruning is not for the faint of heart.  It literally means cutting your shrub all the way to the ground and letting it regenerate.  This is best done when a shrub has really gotten out of hand.  Before doing so, consider the following:
Is the shrub healthy and vigorous?
Is this a shrub that will produce abundant new stems?  (Old lilacs that are non-producers or tend to develop powdery mildew are perfect candidates!).
Is this a grafted shrub?  If so, be careful not to cut below the graft.

This is not always the easiest of garden chores, but doing before the heat of summer and the extra weight of  leaves makes it a whole lot easier. Get busy!