Pruning, 2 Ways . . . . How to Prune Your Shrubs

Let’s start with the process. . .

There are 2 main methods of pruning I recommend for homeowners.

  1. Rule of Thumb
  2. Rule of Thirds

But what do these mean???

Rule of Thumb:

This is a great method for lilacs, hydrangeas, dogwoods, roses, etc. . . .

Look at your hand, look at the base of your thumb, any stems larger than the base of your thumb should come out (yes this varies in size per person and that is okay).  What this does is help thin out the old stems to allow for the newer, usually healthier, growth to absorb the nutrients available.  Now one thing I hear a lot is, “the previous homeowner never pruned or took care of their shrubs so all of the stems are bigger than my thumb!”  That is okay, life happens.  What I would suggest is implementing the “Rule of Thirds” until the shrub is at a point that you can move back to the “Rule of Thumb”.

Rule of Thirds:

This is great for larger shrubs (privets, hedge cotoneasters, etc), out of control shrubs, or any shrub (or tree) in general . . . .

Here it is, if you don’t know what to do; take out a third of the height, a third of the width, a third of the shrub.  NEVER EXCEED MORE THAN 1/3 OF THE PLANT.  If you take out more than a third of the overall shrub (or tree for that matter) you run a very high risk of the shrub (or tree) not surviving.  Note, this can be a very extreme way of pruning and trimming, it is better to go less and be safe than too much and your plant dies.

In either method you DO NOT want to exceed more than 1/3 of the shrub (or tree) in 1 growing year!

When to prune or trim? 

Ideally, right after they bloom! 

The key is to not prune off any buds that will give your shrubs those beautiful flowers we want.  For example a lot of springs blooming shrubs will “set” their blooms in the fall so you don’t want to prune your lilac, for example, in the fall because you will loss all of your spring flowers.  Alternately most fall blooming shrubs, like butterfly bushes will put on their buds in the spring after the last frost so you don’t want to loss your fall flowers by pruning them in May.  So for lilacs, roses, hydrangeas, etc you want to prune late spring/early summer; spireas, dogwoods, potentillas, etc prune more late summer; blue-mist spireas, butterfly bushes, etc you want to prune more beginning of October or right before the first frost. 

But my shrub doesn’t bloom!?  Pruning in the fall is your safest bet, even if your shrub happens to set its buds in the fall the worst you have done is just delay their blooming for a month or a season.

How often should I prune or trim?  Trick question . . . if your shrubs are out of control or haven’t been maintained you may have to prune twice (once in the spring, once in the fall). . . . if you are maintaining them once a year every 2-3 years is sufficient . . . . never exceed twice a year but the frequency is up to you.  BUT again DO NOT want to exceed more than 1/3 of the shrub (or tree) in 1 growing year!