When to Prune Your Spring Shrubs

When Do I Prune Spring Shrubs? 

Why Prune? 

Pruning is the selective removal of specific plant parts for the benefit of the whole plant. Some reasons to prune are to train a plant, maintain plant health, improve the quality of flowers, fruits, and stems, restrict growth, remove damaged and diseased branches, and to increase air circulation that can decrease specific plant diseases 

When is the best time to prune? 

The best time to prune spring-flowering shrubs is immediately after they finish blooming. If they are pruned before blooming, the flower buds that developed last year will be removed reducing or eliminating flowering in the future. Spring will bring a flush of new growth. At the end of spring into early summer, tip pruning is needed to maintain shape and correct growth on evergreen shrubs. This involves lightly pruning any new growth to maintain shape and form (about 4-6 inches). Summer-flowering shrubs should be pruned in late winter or early spring (end of February to the end of March) to promote growth by the summer. 

It is recommended to avoid any pruning during mid-summer and mid-winter when shrubs are already stressed from the environment. Pruning is an invigorating process that stimulates new growth which may not be ready by winter. This may lead to cold damage or winter injury. The exception to prune at any time is if plants are dead, diseased, damaged or have double-crossed limbs. You should not prune newly planted shrubs unless limbs are damaged. Newly planted shrubs need all the leaves possible to encourage root regeneration. 

Should I prune all my spring shrubs? 

Observe the plant before you began pruning. For shrubs like Forsythia and Evergreen, it is now too late to prune back until next year. By pruning them now you may cut off next year’s flower blooms. Now is a good time to prune Azaleas that have already bloomed. Prune them to shape, or to lower them below windows. Pruning helps to keep them more compact. 

Fertilizing after pruning with a low nitrogen fertilizer can be beneficial to them. 

How do I Prune? 

There are two basic approaches to pruning ornamental shrubs. Informal pruning encourages a natural form and branching structure. This involves a combination of thinning and heading cuts. Most plants are healthier with this approach and still have a full canopy with uniform growth throughout. The second is formal pruning which is historically reserved for hedging and topiaries. Many hollies and boxwoods have been traditionally maintained in this style. This encourages a dense branching structure on the outer portion of shrubs. Very little light can reach the interior of the plant and there is very little air flow within the plant. This creates an environment for secondary diseases, as well as conditions for pests to thrive. One way to alleviate this and keep formal pruning healthy is too thin (or pocket prune) denser branches back to their growing point or main stem. Never remove more than one third of the foliage in one year with this method. Most landscapes have a combination of both formal and informal pruning of shrubs.