Why, When and How to Prune Trees and Shrubs

 beautifully pruned tree and shrubs

Late winter and early spring is a good time for pruning many trees and shrubs. Healthy trees and beautifully-shaped shrubs make your landscape more beautiful and more pleasant to live in as well.

Why Prune?

We prune trees and shrubs for their health and for our aesthetic pleasure. Pruning will:

  • Repair Damage. Broken limbs or stems are an invitation to pests and disease. When they are removed properly, the tree or shrub will be able to heal itself. Pruning for damage repair should be done as soon as possible after the injury occurs.
  • Remove Nuisances. The forsythia grabs your hat every time you pass. The spirea blocks the living room windows. The oak casts so much shade that you can't grow flowers or grass underneath it anymore. When trees and shrubs become nuisances, it's time to prune!
  • Shape Growth. We shape trees and shrubs to create the most beautiful appearance in our gardens.
  • Special Effects. Topiary, espalier, even bonsai . . . pruning is a technique used to create many special effects in the garden.

Pruning Tools


Removing large branches or those that are high off the ground is a dangerous business! Home gardeners should limit themselves to jobs that can be accomplished while their feet are firmly planted on the ground. Call an arborist for the dangerous tasks.



Hand secateurs are an essential tool for the gardener. They can have bypass blades, where both blades are sharp and work together like the scissor blades. They can also be anvil types, where one blade is sharp and the other has a flat surface.


Loppers are large, long-handled secateurs used to cut larger branches. Many are constructed with a ratchet mechanism at the spot where the blades join. This lets the gardener open the blades further to accommodate large branches and also to exert more force.

 pruning saw

Pruning Saw

Pruning saws are specially designed with large teeth to cut green wood efficiently. Never try to prune with a regular saw! Some pruning saws have a straight wooden handle, while others have a curved metal 'crossbow' handle.


Trees are normally pruned in late winter or early spring, when the tree is dormant. The tree will heal the wound most rapidly at this time, because all its stored energy is available for the job.

Cutting out deadwood and diseased branches will make the tree healthier. Remove any crossed branches that are rubbing against each other and leaving a wound in the bark.

If you need more light under the tree, remove some of the lower branches. Remove any branch that blocks a path or causes a problem for people walking in the garden.

You can also make a tree more beautiful. Remove misshapen growth, thin out some branches to make the tree seem more graceful, or remove some top growth to encourage heavier blossoming. Follow the natural growth pattern of the tree for best results.

Always cut at the base of the branch, just outside the branch collar. That is the bulge where the branch merges with the tree. A cut just outside the branch collar will heal quickly. If you cut halfway down the branch, it will die back to the branch collar anyway, and the dying wood will invite diseases and pests.

To prune a large branch, make the first cut into the bottom of the branch. Then cut downward from the top of the branch until the branch is sawn through. If you start with the top cut, the bark below the branch may be torn away by the weight of the falling branch, leaving a large wound.

There is not need to seal the stump with paint or tar if you've cut just beyond the branch collar. Gardeners were once advised to apply sealer to the cut, but research has shown us that the tree will heal more quickly without it.


Shrubs are multi-stemmed woody plants, growing with many stems coming out of the ground in a group. In an old bush, there are likely to be many stems growing very close together. Often, some of the branches are dead. This makes an impenetrable - and intimidating - mess!

Always prune stems at ground level, cutting higher results in a badly-shaped, ugly shrub. Start by removing any dead, dying, or damaged stems. Often that is enough to make an overgrown shrub beautiful and healthy again.

If you choose to reduce the size of the shrub even further, remove the oldest branches next. Start at the center of the shrub. Not only are center stems usually the oldest, but removing them will let air and light into the center of the bush. That will make the shrub healthier and encourage flowering.

Don't remove more than one-third of the stems in a single year. Pruning more heavily can cause stress for the shrub.

When to Prune?

When working with flowering shrubs, pruning should be timed to avoid interfering with the shrub's blooming period.Shrubs like lilacs and forsythia, which bloom in the spring, flower on old wood - that is, wood that the bush grew the previous summer. Cutting back these bushes in late winter will result in no flowers to enjoy that spring. Wait to prune these shrubs after they have bloomed. You can prune while the bush is in bloom if you want cut flowers for the house. Shrubs like bluebeard (Caryopteris), which flower in the late summer or early fall, bloom on new wood - that is, wood grown in the current season. If you cut these bushes back in late winter, you'll encourage new growth and heavy flowering.

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Why, When and How to Prune Trees and Shrubs