Will My Trees and Shrubs Survive the Snow? 

When Waukesha County was hit with a blizzard-like snowstorm that dumped over a foot of snow across most of the county January 12- 13, many of us panicked at the sight of our beautiful trees and shrubs stressed and bent under the weight of the snow. Then, the extended streak of severe cold and intense wind chill meant the snow was frozen and would not fall off to relieve the pressure.   

“As I panned the landscape with my eyes, everything was burdened by the snow. It was an epic snowfall,” observed Chet Celenza, a professional arborist based in Mukwonago. Celenza indicated we will not see the extent of damage to trees and other plants until the snow melts in spring. Wayne Eslyn, certified nursery professional and owner of Grandiflora Landscaping, commented, “Snow cover in Wisconsin is important. A big snowfall insulates all plants underneath the snow.” Both men have over 40 years of experience in their respective professions.

Both Celenza and Eslyn explained that the problem with the recent snowfall was its high water content, which caused the snow to stick to and pile up on branches, especially evergreens. Even extremely high winds couldn’t shake the snow accumulation off branches. Eslyn explained that if people didn’t knock off snow from their plants as it was falling, but attempted to after the snowfall, they may have damaged limbs that could snap due to the extended severe cold temperatures. Branches that are simply bent may come back close to their original form naturally or if encouraged by tying them up. Unless trees or shrubs were damaged so severely by the storm to the extent they need to be taken down or removed, homeowners should be patient because the plants will need time, sometimes years, to grow back to their original structures.  

“There will be a fair amount for all of us to do in spring,” said Eslyn. “Plant limbs have stretched, and plant cells have broken down.” He shared that, from a horticultural perspective, cold is judged not only by the temperature but also by the duration of the cold weather. Native or hardy plants produce more alcohol or “anti-freeze” when there is a gradual transition from summer to winter. The hard freeze and prolonged cold after this last storm may cause many plants to shrivel and turn brown.   

He added, “Evergreens, including arborvitaes, may appear to be green and healthy over the winter and into early spring, but in June or July we may begin to see them brown out. It takes heat to dry them out and for the damage to show. Burning may occur due to the high winds and windchill. As soon as the weather warms up, damaged tissue will turn brown, so homeowners will need to trim this out to encourage new growth on their trees and shrubs.” Eslyn explained that in spring, healthy new branches on damaged trees and shrubs will grow upwards, which is common after a severe storm, even if their limbs remained bent over during the winter. He added that throughout Waukesha County, the number of trees that snapped under the weight of the snow in natural areas could create fire hazards, a concern we won’t fully realize until next summer.

Protecting Trees & Shrubs from Future Storms 

During future storms, Celenza suggests that people with young or small trees or shrubs should knock snow off them every hour or after every few inches of snow to ensure they can spring back up once temperatures rise above 30⁰. He recommends that if treetops are too high to reach, a 16-foot painting pole could be a useful tool for knocking snow off taller trees, but only if the homeowner feels safe doing so. A hard hat and eyeglasses should be worn for protection in case a branch snaps and falls.

However, the best protection is tree and shrub maintenance throughout the year. This begins with proper plant selection for an intended space. Local nurseries and garden centers are excellent sources if homeowners need assistance making an appropriate choice. Trees and shrubs should be planted at least one month either before the first frost or after the last frost in a hole dug slightly wider and deeper than their root balls. Thorough watering, considering rainfall, and fertilizing during the spring and fall will help ensure healthy plant growth. Trees with small trunks may benefit from staking to protect them particularly from wind damage. 

As trees and shrubs mature, regular pruning will result in healthy, safe and aesthetically pleasing plants. Trees should be pruned during winter months when they are dormant to avoid disease brought in by insects attracted to exposed sap. Pruning cuts should be made right above a growing point and no more than one-third of total height or branches should be removed. It is best to remove fewer branches than to damage the plant.  For tall trees where branches are out of reach, Celenza explained that typically about 80% of hollows or weak structural areas cannot be seen from the ground and he recommends engaging a professional arborist to climb the tree to perform an inspection. Dead wood makes trees fragile and so cutting out the dead branches will help prevent future damage during storms. Tree limbs hanging over houses and garages should be trimmed to within three to five years of growth clearance to protect the tree from rubbing against the house or roof. Cutting back further may compromise the tree. 

Celenza commented that he often visits properties and sees a tree’s lower limbs have grown out beyond its crown like a lion’s tail with a tuft at the end. Those branches need to be trimmed out to keep the tree strong and healthy. Celenza said, “You have to have an eye for the structural aspect of the trees. Your eye needs to go from a tree’s base to its top to determine if it’s structurally sound. Tree maintenance is a combination of safety and aesthetics.”

While tedious work, Celenza shared that arboricultural cabling can be used to prevent columnar arborvitaes planted like a hedgerow from being pulled down by snow. Eye lag screws can be attached to tree branches and threaded with cabling to pull the branches and trees together. When snow comes again, the arborvitaes will remain upright.  

For sensitive plants such as ground covers and ornamental grasses, Eslyn recommends covering them with pine boughs or straw in anticipation of cold weather. While raspberry plants are hearty, blueberry plants should be covered with straw. Perennial beds should be covered when temperatures drop below 20⁰. He does not recommend wrapping arborvitae to prepare for winter. “What’s the point of covering evergreens with burlap when the purpose is for them to be ever green?” Eslyn suggests not performing fall cleanup on hearty, flowering shrubs like spirea. Simply let the snow accumulate on them, clean up in spring and enjoy their colorful flowers.   

Looking Forward to Spring

Eslyn said that it will be interesting to see how the magnolias and forsythias bloom in spring because it is normal for their buds to be on them at this time. He shared that seasonal snowfall can be “measured” by the distance from the ground where forsythias bloom in the spring. If 18 inches of snow fell over the winter, forsythias will bloom 18 inches above ground level. 

Cold weather isn’t always bad for trees. Eslyn noted that trees in a cold-weather state like Wisconsin actually need “chill hours” to thrive. For instance, apple trees need 500 to 1,000 chill hours during the winter to encourage flowering and fruit production. He commented that despite the storm’s downsides, “We needed the water the last snowfall will provide. The snow will melt and the water will come to us more gently. I would rather have this than an inch of rain.”

As we look forward to warmer weather, here are a few spring care tips to consider to promote healthy and safe trees and shrubs able to weather future storms:

• Clean debris such as leaves or decayed fruit from underneath trees and shrubs to avoid fungal growth.
• Inspect trees and shrubs for damage, such as dead or broken branches or browning, to determine if they should be trimmed or treated. Most often, plant wounds should be left to heal on their own. Professionals may need to be consulted.
• Look for indication of pests or disease to determine if preventative treatment or pest removal is required.
• Consider mulching around trees and shrubs, being careful to avoid laying the mulch against trunks, which may foster fungal growth.
• Remove dead or damaged branches.
• Fertilize depending on the type of tree or shrub. 
• Water regularly depending on the amount of rainfall.
• Enjoy your lush, green trees and shrubs!