When Can You Trim Evergreens?

The timing of a tree trim is crucial for some types of trees, but evergreens can endure a light pruning job at nearly any time of year, according to Virginia Cooperative Extension. Gardeners can trim trees for the holiday season even during the coldest winter weather as long as the trim is light. Extensive pruning jobs require more careful timing to protect evergreens' health.

The safest time to prune evergreen trees and shrubs is late winter or early spring, between the months of February and early April. This gives evergreens a chance to heal wounds while the weather warms for spring. Because a trim always inspires new sprouts, timing a trim for early spring -- just before new growth starts -- allows the sprouts to emerge in time for spring.

Gardeners may lightly prune a second time in the summer if necessary. For instance, the optimal time to trim pines is during the candle stage in June or early July while evergreen shrubs can handle some pruning at the same time. These light trims must occur before autumn sets, however, as trimming in fall causes new growths that may not harden off in time for winter.

Evergreens rarely need trimming unless a branch becomes diseased or broken. In these cases, gardeners should remove the branch as soon as possible to avoid the spread of disease or further problems. The only dangerous time to do this is during wet weather, according to the University of Idaho bulletin "How to Prune Coniferous Evergreen Trees," as wet weather encourages contamination of tools. A few days of dry weather keeps evergreens safe from disease and rot during branch removal.

Pruning at an unsafe time of year will not kill an evergreen, but it will compromise its health, which is especially true when gardeners consistently prune diseased trees in wet weather or perform major trims in autumn; these evergreens will weaken or suffer damage that make each subsequent trim more dangerous to its health.