Regular pruning is beneficial to shrubs and trees. Selective trimming, thinning, and cutting will generate new growth, denser foliage, and more fruit/flowers. How often and when to prune though seems to be the confusing part for many gardeners. Knowing a few basic rules of when to prune plants will do wonders for the overall health and appearance of the garden.
What Pruning is Not
The definition of pruning is: trim by cutting away dead or overgrown branches or stems, especially to increase fruitfulness and growth.
It is not the art of topiary. Plants used for topiary grow in a unique manner that allows them to be trimmed into tight and uniform shapes year-round. Pruning large leaf plants with this method will leave bare spots and an odd-looking plant.
Pruning is not size control. Trying to restrict the natural size and shape of a plant can do more harm than good. Too much pruning can stress the plant. If a smaller shrub is needed, then a smaller shrub should be planted. Pruning an eight-foot shrub down to four-feet will prove to be an impossible task.
When To Prune
A general rule of thumb for pruning plants is to do it during the plant’s dormant season. This is the best time for pruning plants because you won’t cut off any new growth or new buds. Pruning too late in the season can damage the plant and pruning too early in the season can limit the fruit production and flowers. A good example of the risk in pruning during the wrong season is oak wilt fungus. Cutting oak trees during Spring and Summer opens them up to the spread of oak wilt fungus by sap beetles. The best time to cut or prune oaks is during the dormant season of November – March when the insects and fungus are inactive.
For Spring flowering plants such as Lilacs, Weigela, and Crabapple, the best time to prune is right after they’ve bloomed and faded. These early bloomers typically set new buds right away. Waiting until Fall or Winter to prune may cut off these buds. Cutting off new buds will result in a flowerless plant in the Spring.
How To Prune
If a shrub or tree has become overgrown, it’s easy to see what areas need to be cut back. Any rogue branches, crossing branches, or uneven shape can be trimmed back or completely removed. When clipping, go all the way to the base of the branch or just past a new bud. Do not randomly cut halfway down the branch. This will leave lots of bare ends and uneven growth. If the plant simply needs to be cleaned up and shaped, visualize the new form and size before cutting. As stated before, pruning is not size control. Only take off what is needed to regain the natural shape and density of the plant.
With some shrubs such as Lilac, Dogwood, and Willows, pruning aggressively is needed for healthy growth. Cutting 1/3 of the shrub’s branches down to the ground will actually stimulate new growth without damaging it. This will keep the shrub’s lower half looking full instead of becoming top heavy consisting of only old branches. This method would be to thin out the plant instead of just maintaining its shape.
No plant is completely maintenance free. Annual pruning however will keep the plant looking its best season after season. It might be obvious when a plant has become overgrown, but knowing when and how to prune it will keep it thriving. Prune during the dormant season and cut at the base or just past the bud to ensure a healthy perennial, shrub, or tree.