Even in the midst of harsh weather, winter can offer some spectacular nature views. The beauty of the sun sparkling off of trees and shrubs coated and frozen in ice is a marvelous sight. But you’re snug in your coat, and trees are seemingly unprotected from the elements. An alarming thought occurs to you- Can trees freeze to death?
The short answer is no- whew! However, they can sustain injuries and damage from winter weather. After a tough winter, you need to give your trees and shrubs a check-up. Find out how trees typically survive the winter, which weather conditions cause damage, and how you can treat and prevent further damage to your trees.
How Do Trees Survive In The Winter?
Trees are up against two main obstacles during winter: lack of liquid water and frigid cold temperatures. Tree tissues cannot take up water from snow as it melts because exterior bark acts as a tight barrier. The bark is also positively functioning as the primary protective layer that shields tree tissue from physical damage.
Trees hibernate during winter, going into a state called dormancy. All of the regular processes slow down, including metabolism, growth, and energy consumption. Leaves fall early on in dormancy so that the tree doesn’t have to spend energy supporting them.
Before dormancy begins, trees take up extra water and stock their cells. Water is moved and stored between the tree cells to keep them from freezing and dying during extreme cold. That water inside the tree actually does freeze, but first gives off a small burst of heat; enough to keep the tree cells alive. Finally, to further adapt and tolerate the cold, trees transform starch to sugar inside their cells. And that’s the secret science of how trees survive winter!
What Is Winter Die-Off?
Despite all the natural strategies trees have to survive the winter cold, not all parts of the plant always remain intact. Winter die-off is an injury that occurs when parts of the tree freeze and die off during the winter. These parts of the tree no longer produce new cells or growth.
Tree limbs that suffer from winter dieback are vulnerable to breakage and falling without warning. This becomes a big liability in high winds and spring storms!
Outward signs of winter die off:
- Vertical cracks or holes where the bark is missing
- Dry brittle wood that easily breaks off
- Large amounts of fungus
- Exposed smooth wood with almost no bark
- Sores or cankers on branches
Other Types Of Winter Tree and Shrub Damage
Sometimes referred to as southwest injury, Sun scald usually occurs on the southwest side of developing tree trunks. In Colorado, December through March are the months when young or thin-barked trees may be at risk. Colorado receives more sun than other parts of the country during the cold winter months, so sun scald happens more frequently here.
For example, a typical sunny winter day in Denver could reach 60 degrees Fahrenheit. High-intensity winter sunlight heats up the tree trunk and causes it to come out of dormancy. Tree cells and tissue become active again, only to be killed when the sun goes down and temperatures plummet at night. Over time, this injury may appear as sunken and discolored bark. The bark could even fall off, revealing dead tree tissue.
Leaf scorch is simply the browning of plant tissues caused by unfavorable weather conditions. Plants are primarily at risk for injury on dry, windy, warm or sunny winter days when the ground freezes. Under these circumstances, plants can’t move water from the frozen soil to replace the water missing from the exposed leaves. As a result, leaves curl and become limp. Next, they brown at the tips and the veins, looking scorched. You may see some plants with leaves that roll up and inward. This is a coping mechanism. The plant is trying to reduce leaf exposure.
This type of damage occurs when a plant’s tissues dry out from wind or ice-melting chemicals, lack of moisture in the air or soil. Some tree species, such as Evergreens, are more vulnerable when they are dormant because their leaves never stop losing water.
The ground freezes in winter, making it difficult for root systems to take up water. Damage to the foliage becomes visible when the roots are taking in as much water as the leaves evaporate. The damaged leaves are usually on the side of the plant facing the wind, where most of the evaporation happens.
Soil nutrients and composition is important to the health of trees and shrubs year-round, but especially in winter. Dissolved salts in road runoff can alter the structure of the soil, causing it to become compacted. In this state, trees access to nutrients, water, and oxygen is limited. This puts the tree or shrub under stress and causes damage to shoot tips and young leaves.
Does your city management get heavy-handed with deicing salt? Airborne spray and surface application of salt along your property’s sidewalk and street curb can cause leaf scorch. It can even kill buds and branch terminals! When desiccation occurs to vulnerable tissue in the buds, the damage is irreversible. In the soil, salt can accumulate and cause roots to die from desiccation as well.
Blighting of New Growth
When temperatures spike, and we experience an unseasonably sunny warm day in February or March, plants get confused. The strange shift in temperature can stimulate buds or shoots on trees and plants to develop too early. Then cold weather and frosts return immediately killing the new growth. This also hurts future leaf development. The result is dark buds and leaves that drop off.
Frost Damage and Cracking
When pavement warms and cools it will crack over time due to the extreme temperature changes. Trees can experience a similar phenomenon. Trees with thin bark that receive both direct and reflected sunlight can experience bark temperatures into the 70-degree range, even though the air temperature is below freezing! If water moves into the warm under bark tissues, the tree will be vulnerable to rapid freezing and tissue death. In the spring, the tissues dry-out and then crack, usually on the south or southwest side of the tree. Fruit trees are very susceptible to this problem.
Blasting of Blooms
Star magnolia and lilac flowers are most vulnerable to this type of damage. It happens when flower buds swell and then freeze during cold snaps or late frosts.
Ice and Snow Damage
Tree limbs and shrubs can become weighed down under the weight of heavy snowfall and ice, resulting in bent or disfigured branches. Gently remove snow to alleviate the burden from the tree. Ice cannot be removed from branches. Attempting to deice a tree can actually cause further damage to brittle branches.
Treating Winter Die-Off
Fielding Tree and Shrub Care specializes in removing hanging limbs and creating clearances that may be obstructed by lower limbs and potential die off. Looking for signs and determining which branches are affected can be tricky. You don’t want to miss any, but you definitely don’t want to remove branches unnecessarily. Let the experts evaluate your trees for potential winter damage. The last thing you want to do is a DIY hack job on your beautiful landscaping.
Treating winter die-off is an essential part of home maintenance for spring. Spring thunderstorms and strong winds will bring down any damaged limbs. You can avoid a major accident by using professional tree trimming services to care for your trees now!
Other Management Strategies
Try these simple steps to prevent and control harsh winter damage to your shrubs and trees:
Give your trees some cover! Crepe paper commercial tree wraps insulate bark and are an effective way to prevent sun scald. Start at the base of the tree and wrap trunks upward to a point just above the lowest branches. For best results, do this n In late October or November before winter fully sets in. Then take off the tree wrap in April to avoid girdling and possible insect damage. Wrap young trees each winter for a few years until bark thickens and the tree can protect itself.
Careful where you shovel! Try not to pile snow around plants or trees if it could contain salt deposits Also keep away from areas where runoff might reach plant roots. Kindly ask road-maintenance workers if there is a way to direct salty runoff away from your lawn. For future landscaping, consider planting a hedge of hardy evergreens. These salt-tolerant plants can act a barrier, deflecting salt spray away from your other shrubs.
If you can’t avoid salt runoff, apply two inches of water over a two- to three-hour period to flush the area around the plants in early spring. Repeat this process later in the week. Flushing the soil will help to remove lingering the salt. If your plants are getting sprayed with salt residue from the road, gently hose them down whenever needed.
Frost Damage and Cracking
To prevent frost-cracking, simply shade the trunk of the tree. A burlap wrap will work! Focus on pruning and fertilizing in the correct seasons. Avoid late summer or early fall, because it can encourage sudden push of new, tender growth. If need be, use a slow-release option. In spring, wait until the plant has broken dormancy and the threat of low temperatures has passed before tackling any pruning projects.
Prevent all sorts of damage with proper winter watering techniques! Give your trees a drink and soak the soil several inches deep and then allow it dry between watering. Lightly spraying foliage with a hose in the spring will also help wash deicing salts from the leaves or needles. Deepwater will flush salts through the root zone faster to help reduce desiccation damage. Deep watering will also encourage deeper rooting during the growing season which will help reduce desiccation damage from moderately dry periods and frozen soil.
Winter was tough on all of us, trees included! Our certified arborists can evaluate your trees for winter die off and other damage during a quick consultation. Contact us at Fielding Tree & Shrub Care today to get your trees in shape for spring!