Pruning Flowering Shrubs

Let’s face it, our flowering shrubs can get leggy and too large for their intended spaces.  We can definitely help them with pruning.  This helps them maintain a desired shape and can increase flowering.  Some of us like shape with our shrubs, while others prefer something more natural.  You can prune to achieve either look.  (I’m not talking lightbulb shape here!)

We are specifically referring to pruning of flowering shrubs that are deciduous or woody shrubs.  They have a season of bloom and the rest of the time have decorative foliage.  When does your shrub bloom? You want to make sure that you are not cutting off the flower buds for next years bloom. For shrubs like Forsythia, Lilac and Rose of Sharon, you would prune these within two weeks after flowering. You could head these back from the top growth. For example, to reduce the overall size of the shrub, use either hedge pruners or secateurs.  Or alternatively, you could thin the shrub out.  This allows more sunlight to penetrate the branches and encourages more blooms.  Shrubs like Forsythia bloom on new wood. Removing some of the largest canes of a mature Forsythia allows new growth.  You will notice greater blooming. In addition, Forsythia usually grow like weeds and can handle a good prune!  Do you need to do this every year? This is totally up to you.  I do encourage you to prune your flowering shrubs at least every three or so years to maintain healthy grow.

For Lilacs, we have the old school huge Lilac bushes and the new varieties that stay very tight in the landscape, almost ball shaped but not quite.  Some are even reblooming varieties.  The right time to prune these varieties is again within two weeks after blooming.  This will ensure that you aren’t cutting off future buds.

To prune shrubs like Weigela that flower mid-June to July, you will be following the same principle by pruning very shortly after flowering.  Usually, Weigela do not require as much pruning as their growth is not as vigorous as some other flowering shrubs.

What happens if your shrubs need pruning and you’ve missed your pruning window?  You can prune at any time of the year, knowing that you may be pruning off your flower buds for next years flowers.  Is that the end of the world?  No, it doesn’t affect the health of the plant at all.

Recap- Pruning shrubs within two weeks following blooming to prevent cutting off next seasons flowers.You can reduce the overall size of the shrub by cutting off the height and width (heading back), or you can selectively prune out the largest canes. Flower production is stimulated by light, pruning allows more light into the shrub.