Monday, May 12, 2014

Pruning Spring Flowering Shrubs

As the spring has finally arrived and your spring flowering shrubs start to bloom, you might start to wonder, when should I prune these shrubs.  Spring flowering Shrubs such as Forsythia, Double flowering Plum, Lilac, rhododendrons and Azaleas flower on old wood.  If you prune them in the fall or early spring you will be cutting off the flower buds, thus giving you very little show.  The best time to prune these shrubs is right after they flower.
When pruning you should remove approximately 1/3 of the shrub each year,   this will give you a healthy plant and the best show.  Start this process by removing dead or broken branches right to the ground.  Then you remove the oldest, thickest canes with to the ground.  At this point you may be close to the desired 1/3 removal.  The remaining branches you remove should be chosen to give you the desired shape and height you want.   Also remove any spent flowers, this will allow the plant to give its energy to growing rather than producing seed.
Occasionally you have a shrub that is very over grown and woody that flowers very little.  Normal pruning does not always fix the problem.  That is when I would suggest doing a rejuvenation pruning.  To do this you remove all the branches of the plant leaving only 2-4” of the shrub at the ground.  This is best done in early spring before the leaves come out.  Thus you will have to sacrifice the flowers for that season but it will be worth it in the end.
The following shrubs can handle this type of pruning.  Potentilla, Dogwood, Lilacs, Hydrangea, Honeysuckle, Mockorange, Weigelia, Viburnum (Cranberries), and Elders.
Pruning - Thinning - Picture 1
Pruning Rejuvenation - Picture 2

Pruning - thinningRejuvenation pruning
Posted by Tammy Jensen at 3:15 PM