Winter damage: How to spot it, prevent it and make it better

Winter is rough on our plants, especially in Indiana where winters can be unpredictable and temperatures and wind chill factors can swing dramatically in short periods of time. We see people every spring who bring in plant samples or photos of damage wondering about the cause and how to fix it.

Winter damage may be immediately apparent on plants even before the end of winter. Other injuries do not show up until after new growth has resumed in spring. Some flowering trees bloom gloriously, only to die for no apparent reason after the leaves emerge. Some forms of winter damage may not be evident until June or later when plants are under heat or drought stress and water does not flow well through winter-damaged tissue.

A few general care tips when dealing with winter damage or injury. Then we’ll get into some specific types of damage.

• Be patient. On deciduous shrubs (ones that lose their leaves in the fall), wait to see what leafs out before you confirm what is actually dead. It will take shrubs a bit longer to come out of their winter hibernation.
•  Prune as needed. In our haste to fix the problem, we sometimes act too early, pruning before extreme temperatures have passed. This can cause even more damage. Wait until the threat of late spring freeze is over and then cut broadleaf evergreens before the onset of new growth.
• Fertilize in early spring. After pruning, spread a complete fertilizer such as 10-10-10 under the drip line of your tree (i.e. the furthest point of your branches as they extend around the tree) so the spring rain will water it in. Water in with a natural product like Organic Plant Magic to help your plants quickly absorb nutrients and build strength.
• Water generously. Soak the root area with a sprinkler (check out How do I know when to water and how much? or Ask Our Expert if you have watering questions) during dry periods in the summer or fall to prevent further injury and to keep your trees and shrubs strong.

Now a look at the most common forms of winter damage, what you can do next and how to prevent it from happening in the first place.  

1) Frost Damage

Unfortunately, this is a common problem that comes with below-normal winter temperatures, below-normal temps in early fall or late spring or winter temps that fluctuate and cause tender new growth to freeze.

How to spot it? New foliage that turns brown or black. Dead buds or branches or delayed leaf development on older parts of the branch. 

What to do now? Once the threat of frost has passed, prune back the damaged foliage if it hasn’t already dropped on its own. Pruning stimulates new growth and in most cases, the plant will fill back in. 

How to prevent it? Always select varieties of trees and shrubs that are hardy in your area. Certain types can be more susceptible to winter damage (including magnolia, forsythia, rhododendron, azalea and holly) so choose and plant with exposure in mind.

Be sure to ‘harden off’ plants early so they have ample time to prepare for winter. That means you want to avoid late-summer/early fall pruning or fertilization that can stimulate new (vulnerable) growth. A rule of thumb: do not fertilize trees or shrubs after mid-July, or if your leaves are calling for a little food, use a slow release or organic fertilizer sparingly. Along the same lines, don’t bring a tree or shrub out of dormancy too early by pruning in early spring. Be sure the threat of frost and severe temperatures have passed before encouraging new growth.

2) Winter Dessication

Winter what? You may not know it by name, but you’ve definitely seen it. In layman’s terms, this is when your tree or shrub is drying out, the plant version of being dehydrated. This type of injury happens when your plant is losing more water through its foliage than it is taking up through its roots, something that can happen easily with excessively dry or frozen soil. Strong, drying winds, direct sunlight and extreme temperature fluctuations all increase the rate of water loss, even through the coldest periods of winter. Most susceptible? Buds, young bark or foliage of evergreens.

How to spot it? Dried, ‘burned’ and/or brittle foliage concentrated on the side of your plant that is facing direct winds (and exposed to the most evaporation). Browning needles on evergreens.

What to do now? Damaged foliage often falls or is pushed off by new growth, but you can prune or strip it once the threat of severe temps has passed. Don’t do it too early or you’ll risk even more drying to exposed areas.

How to prevent it? Moisture is very important to helping trees and shrubs stand up to winter temperatures. Give your plants extra water during dry summer periods and before freeze in fall and early winter. If you see signs of drying, you can even grab your house or watering can on one of the warmer days in winter to water the frozen ground and release the moisture into the soil for your plant to use.

Maintaining a thick layer (2-3 inches) of mulch and/or leaves will also help to conserve moisture and protect the root system.

3) Broken Branches

Snow and ice can literally weigh heavy on branches, especially multi-stemmed evergreens like yews, arborvitae and junipers and the smaller, soft and brittle branches of many hardwoods, including Chinese elms, maples and birch. 

How to spot it? Broken or damaged limbs and branches and bent or leaning evergreens.

What to do now? If you’re still in the midst of winter snow, gently prop up or ‘fluff’ snow-covered branches up. Never beat downward on ice-covered (or heavily snow-covered) branches—it can increase the damage and cause even more breakage.

If you already have a broken branch or branches, you can wait to prune until the weather improves. Once it does, or if the branches present a hazard (e.g. hanging over a driveway or sidewalk), remove and prune back to the main stem (or just in front of the nearest live bud) to promote healing and stimulate new growth in spring. 

How to prevent it? Smaller, more vulnerable evergreen branches can be tethered to a stronger one with heavy rope or twine. It’s not the most aesthetically beautiful or easily tackled solution, but if it means saving your tree prior to an incoming storm, it may be worth your time and effort.

Diseased or weak branches can even be removed in fall or early winter to avoid more profound overall damage.

After the storm, you can always gently remove snow (fluff up, don’t beat down) and prop up vulnerable, ice covered branches until the ice melts.

4) Rodent Damage

Mice and rabbits will turn to your trees for food when the winter is particularly cold and food is scarce. Rabbits will target the bark at the base of your tree, especially tender young trees, and mice will tunnel down and feed at ground level. When enough bark is removed, the entire tree can die.  

How to spot it? Base of trunk and/or lower limbs stripped of bark.

What to do now? Aside from preventing further damage, there’s not much you can do but allow the tree to heal. See below for preventive measures.  

How to prevent it? Luckily this is an easy problem to solve. Mice like to hide in long grass, weeds or mulch piles, so keep a 1-2 foot radius around your trees weed- and grass-free. Mulching is a great solution, but be careful not to mound your mulch directly around the trunk of your trees.

The best way to protect young trees (which are the most susceptible to damage) is to wrap the trunk with screen wire or hardware cloth. Secure the wrap with a wire and be sure to bury part of the wire below the ground line (sometimes you can do this just by gently pushing it into the soil).

5) Winter Sunscald

We know that newly planted trees are susceptible to a whole host of issues our established trees can handle. Winter sunscald is one of them. Extreme temperature fluctuations (bright winter sun followed by a rapid chill at night) can cause cracks or other damage to bark tissue. The dead bark falls away leaving the inner or ‘heartwood’ exposed to the elements.

How to spot it? Elongated, sunken or dead areas in the bark, especially on the southwest side of the trunk.

What to do now? Aside from preventing further damage, there’s not much you can do but allow the tree to heal. See below for preventive measures.

How to prevent it? Opinions vary, but we find that wrapping the trunk of newly transplanted trees with burlap or other tree-wrapping materials (for two years after planting) can protect thin-barked trees, including maples, tuliptree, ash and crabapples.

For more information or to diagnose a specific problem, Ask An Expert or give us a call anytime!