Watching leaves and blossoms return to trees after a long winter is a spring highlight for many gardeners. Unfortunately, winter temperatures can harm tree tissues, placing your collection at risk of damage and even death.
Prioritizing tree freeze protection over winter ensures your specimens survive cold temperatures and are ready for a spectacular springtime display. In this guide, we’ll outline which trees are vulnerable to frost and explain how to keep trees from freezing.
Why Your Hardiness Zone Matters
The USDA Plant Hardiness Zones run from zone 1A to zone 13b. Gardeners can use this standard to determine which trees and plants are most likely to thrive in their local weather conditions and withstand extreme temperatures. When you purchase a tree, the product label will likely indicate which hardiness zones it can grow in.
Choosing trees suitable for your hardiness zone is essential. Growing trees outside their recommended hardiness zones increases the risk of frost damage in winter and heat damage in summer.
You can determine your hardiness zone by entering your ZIP code in the USDA Plant Hardiness Zone Map. The map key lists the average lowest temperatures in every zone to help you choose the most suitable trees for your climate.
Which Trees Are Most Vulnerable to Cold Weather?
Certain trees are more prone to frost damage than others. Species that usually require tree frost protection include:
- Apple
- Maple
- Cherry
- Walnut
- Willow
- Sycamore
As a rule of thumb, evergreen trees and species with thick bark are less likely to sustain damage. However, freeze and frost can kill newly planted trees and young trees of any type. Therefore, you should protect trees from frost until they’re larger and more established.
The temperature at which trees and other plants experience frost and freeze damage depends on the species and the stage of the tree’s development. Refer to the information on the tree’s label to determine its ideal temperature ranges.
Frost vs. Freeze: What’s the Difference?
Frost and freeze are both types of tree damage caused by cold weather, but there are several differences to be aware of. Frost happens when ice crystals form on the external surfaces of the tree, which can cause leaf and flower damage. However, frost is less likely to damage the tree’s vascular system, and many species will bounce back when the temperatures improve.
Freeze is much more harmful than frost and happens when the water inside the tree freezes. This causes the cells to expand and can lead to irreversible damage. Tree freeze is most likely to occur during extreme weather fluctuations. Slower decreases in the outdoor temperature allow trees to adjust to the colder conditions and make tree freeze less likely.
Signs of Tree Frost Damage
Tree frost damages the outer surfaces of the tree, and delicate structures like leaves and blossoms are particularly vulnerable. The leaves and blossoms may appear shriveled or burnt, and they may fall off the tree altogether. Newly grown tissues are more prone to frost damage than older growth.
The symptoms of freeze damage are often much more dramatic, and the tree may die altogether without adequate protection. Affected parts of the tree may darken or even appear black, and the damaged limbs or branches may droop or fall from the tree. As the frozen tissues expand, you may notice cracks forming in the branches or trunk.
In fruit trees, frost and freeze damage can affect the plant’s ability to produce fruit buds. Research by Michigan State University shows that temperatures of 28 degrees Fahrenheit kill around 10% of the buds on fruit trees, including apples, peaches and pears. At 24 degrees, around 90% of buds will die off. Fewer surviving buds means fewer fruits to pick at harvest time, and you may not notice the damage until you experience a disappointing yield.
Freeze and frost damage aren’t just bad for the tree itself. Cold weather damage increases the risk of falling branches, which could lead to injury or property damage. Therefore, tree freeze protection is essential for your home and family’s safety.
Tips to Prevent Cold Weather Damage to Trees
Water your trees and shrubs throughout the fall
You may think that it sounds strange to water your shrubs and trees, but you may need to do it, especially if you have newly planted trees or evergreen trees. Since evergreens do not go dormant in the winter, they need moisture to get them through the cold season. Generally speaking, you should water these shrubs and trees an inch a week in the fall. Of course, if you have had a rainy autumn, you may not need to do so. It is also important to water this greenery so that you do not have broken branches, branches can break off due to lack of moisture.
The experts at the University of Minnesota have provided some more great resources on evergreen damage as well some other great ways to protect your yard in the gardening section of their site.
Use an anti-desiccant spray
Watering is not the only thing you can do to keep your trees and shrubs from drying out.
You can also treat your trees and shrubs with an anti-desiccant spray to keep moisture in your trees and shrubs. This is especially helpful with evergreens.
Have your trees and shrubs pruned
Going into winter, pruning is important, especially for trees. You want to have dead or dying branches removed – they could potentially fall off and cause severe storm damage – but you do not want to have your trees thinned too much, as this could make the trees weaker. Pruning younger trees and shrubs can help the greenery grow the right way, with branches that have enough spacing and a good framework for the future.
Wrap your tree trunks where needed
If you have young trees, you may need to wrap their trunks with a material like burlap during the winter. That is because the trunks are still fragile and may get damaged in the winter weather. Sun scald sounds like a summer issue, but it happens in the winter due to the sun reflecting off the snow, and then tree trunks get vertical splits. The burlap protection can also keep the trees from suffering damage due to salt.
Wrap shrubs where necessary
You may need to wrap your shrubs or protect them in some way from the winter weather conditions. Burlap or some other sort of cloth material may work well. Plastic is not recommended, though, as it can heat up in the sun. You may also want to consider a wooden shelter around your shrubs to protect them from the elements.
Talk with your Lawn Doctor professional
Whether you need assistance with seasonal lawn care tips, or with making sure your trees and shrubs are protected for the winter, our Lawn Doctor lawn care experts can give you all of the guidance you need.
