To Prune or Not to Prune: It all depends on Flowering

Posted: March 24, 2013

Late winter, just before bud break is a great time to prune shrubs and trees in our landscapes...

The plants have lots of stored energy from last year’s growth, insects and diseases are not active yet (because of low temperatures), and it is much easier to see branching structure when leaves are not on the plants.

Once temperatures warm up, buds will break, leaves will form, and the plants can put energy into closing the wounds made during pruning. Quick wound closure is important to keeping decay and diseases from infecting the plants.

 If you have a spring flowering shrub or tree such as:

  •  lilac,
  • rhodendron,
  • forsythia,
  • magnolia,
  • crabapple,

you might be concerned about removing too many flower buds.  It certainly will not harm to plant to prune in late winter, but if flowers are important to you and your landscape, you should consider waiting until they are done flowering.  

 Summer flowering shrubs such as:

  • roses
  • potentilla
  • summersweet
  • butterfly bush
generally present less of a problem when we prune them in late winter. On large vigorous plants, heading them back and thinning out older, larger stems (about one third of a fast growing shrub) will help keep the plant within bounds and stimulate new growth from the root system. 

For some shrubs like Red-Stemmed Dogwood, pruning older stems or canes is the only way to keep that red-stemmed appearance because older stems turn gray.  On larger, older shrubs such as lilac, it is important to remove the larger, old stems in order to keep it flowering each year.

Gardeners can also choose between:

  • performing an annual thinning on fast growing deciduous shrubs, removing a third of the stems (typically the older, larger stems) or performing a rejuvenation, which means cutting all the stems back to about six inches from the ground. 
  • On large, healthy shrubs, it will invigorate new growth from the root system as spring begins. Make sure you use hand pruners and loopers to make good, clean cuts, and do not user hedge shears on your landscape shrubs.   Keep the hedge shears for the formal hedges only.
  • Whether you choose to venture out and begin pruning now before bud break or wait until your shrubs flower, getting more information about how to properly prune is a must. Just because it is spring and you have sharp tools is not a good reason to wound and damage your landscape without first gaining some knowledge about how to prune.  

To download a copy of Pruning Ornamental Plants visit,  or surf around the Penn State Extension website for help with your landscape-