Boxwood (Buxus spp.), a broad-leaf evergreen, forms a classic low-growing hedge or you can use it as a decorative shrub. Its green or green-blue color brightens a drab garden in the winter. The shrub, which grows in U.S. Department of Agriculture plant hardiness zones 5 through 8, can be damaged by freezing winds and heavy snowfall. A few precautionary measures will keep your boxwood shrub safe during winter.
As winter approaches, remove leaf litter from the interior of the boxwood. Cut back any dead, dried and brittle branches. Save the heavy pruning for spring, after the last frost date -- not in fall. Pruning shapes the shrub, but the process also spurs the plant into leaf production. New stems and leaves are delicate and low winter temperatures will damage them. Injuries on a plant are like an open invitation to disease and pests.
Soak pruning shears in a solution of 1 part bleach to 3 parts water for approximately 3 minutes before and after pruning to sterilize the tools. This helps prevent the spread of disease.
A boxwood shrub suffers from drought stress when the soil gets too dry in winter. The shrub needs about 1 inch of water each week. Water the boxwood before the first hard frost to keep the soil moist during the winter. If the first few weeks of winter are dry, continue weekly watering for the shrub until the ground is frozen because transpiration -- water evaporation from the leaves of a plant -- does not stop as the seasons change or when the temperatures drop.
Feel the top 1 inch of soil under the boxwood for moisture. If the soil is damp, it is moist enough and doesn't need watering. Dry soil means the plant needs water.
Wrap It Up
Loosely wrap the boxwood in burlap, or create a wind break, to protect the shrub from leaf scorch -- moisture loss in climates with extremely cold winters or for younger plants. The process is similar to a snow skier that suffers from wind burn on his face. The burlap keeps the leaves safe from moisture evaporation, just as a scarf protects your face. You may not notice the leaf scorch until the shrub foliage changes color from green to orange. The damage can go undetected until spring.
If you can't find burlap, use another type of breathable cloth. The condensation that builds up inside plastic sheeting or bags creates a humid environment where mold or mildew form, which injure to boxwood shrubs.
Preventing Snow Damage
Remove light, powdery snow with a slight shake of the branches. If the snow has frozen to the branches, wait for the sun to melt the snow. Wet snow is heavy and the weight can push the boxwood branches down to the point of breaking. Protect your boxwood from heavy snow damage with garden twine wrapped around the branches.
Tying to Avoid Breakage
Things You'll Need
- Garden twine
- Sharp knife or scissors
Find the lowest branch of the boxwood shrub and loosely tie the start of a spool of garden twine to the branch. Gently lift the branch upwards without adding strain or stress to the wood.
Wrap the garden twine upwards around the boxwood, in a spiral formation. Pull the branches upwards as you wrap the twine. Keep the twine taut but not so tight that it cuts into the wood or leaves of the shrub.
Tie the garden twine to a branch at the top of the shrub. This holds everything in place so the branches do not bough and break under the weight of heavy snow.
Remove the twine and allow the branches to fall naturally back into place once the chance of snow has passed.
Final Layer of Protection
Spread about 1 inch of shredded bark or pine needles as mulch around the boxwood. Rodents like to burrow into the warmth and gnaw on the shrub roots if there is a thick mulch layer. The thin mulch layer keeps the moisture in the soil during the winter so the shrub has less stress during the cold months. Keep the mulch at least 3 inches away from the central stem of the boxwood shrub so pests do not harm the plant.