Should You Trim Boxwoods In The Fall Or Wait Until Spring? Here's What We Found

Walk down almost any street and you'll spot boxwoods (Buxus sempervirens) edging yards or framing walkways. This popular evergreen shrub is perfect for plant sculpting, which is part of its charm. Fall might tempt you to grab the shears, but resist; it's one of the boxwood mistakes everyone makes and can actually set your shrubs back. Pruning in spring, by contrast, gives them the best shot at healthy, dense growth. These hardy evergreens grow slowly, so even small pruning mistakes can have a lasting effect on their shape and fullness.

The problem with pruning in the fall is that it pushes the shrubs into new growth just as they should be settling in for winter. Those tender shoots don't have time to toughen up before the cold hits, leaving them open to frost damage. Instead of a tidy hedge, you could end up with dying branches, browned edges, or an overall decline in your boxwood's health.

Come spring, boxwoods are primed for trimming. As the days get longer and temperatures rise, the shrubs will naturally put energy into new growth. Therefore, pruning in early spring, before this new growth begins, is ideal. Starting in spring also gives you a clear look at any winter damage, so you can snip away weak or broken branches without messing up the shrub's natural shape. You can still do light shaping into early summer, but late-fall shearing is still the biggest 'don't' if you want your boxwoods looking their best.

Native to Europe and Asia, boxwoods are hardy in USDA zones 5 through 9, making seasonal pruning an effective way to capitalize on their natural growth cycle. When pruning boxwoods in the spring, make sure to start with clean tools and focus on removing damaged foliage. Also, avoid removing more than one-third of the canopy.

Start by thinning (rather than just shearing) so sunlight can reach the center, which lowers disease risk and prevents the interior from turning woody and hollow. As well, remove any diseased branches. Think of light shaping rather than major cutting, because with these slow-growers, less is more; trim just enough to maintain their natural form. Any undesired growth patterns should be trimmed from within the shrub. Cuts should heal quickly, encouraging dense, healthy foliage. Boxwoods can tolerate some drought, but a layer of mulch and occasional watering during dry stretches is helpful and especially after pruning to aid the plant's recovery. They don't do well in poorly drained soil, so spring pruning can also help prevent root rot by increasing air flow. Pruning is also an ideal time to keep an eye out for pests like mites and psyllids. 

If you're still concerned about the longevity of your boxwoods, pruning can also be a good opportunity to check the soil pH, which the shrub prefers to be around 5.5 to 7.2. If you notice older leaves have turned yellow, it could indicate a nitrogen deficiency. Thanks to their resilience and classic form, boxwoods remain one of the best low-maintenance perennials you can plant in your yard.