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Horticulture topics from gardens to lawns and then some.
Several inches of snow rest on the landscape after a January snowfall in 2014.
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The Resilient Landscape, Preparing Your Plants for Weather-Related Disasters Part 3: Winter Storms


Following is a continuation of my exploration on the aftermath and preparation of weather-related disasters on our landscape plants. You can find the articles on wind HERE and drought HERE.

Frozen Stuff

In the book Weatherproofing Your Landscape, authors Sandra Dark and Dean Hill classify weather-related disasters as the 'Big Four' – wind, drought, flood, and frozen stuff. Now that winter is upon us, it's time to consider the effects 'frozen stuff' can have on our landscape plants.

January 2007 a winter storm coated Central Illinois with over an inch of ice. I remember seeing groups of deer milling around in the roadway, because they were unable to navigate the icy fields and woodlands. Fast-forward to December of 2007 a huge ice storm covered much of the Midwest. I was attending Kansas State University at the time and was preparing to head back to Illinois for winter break, though I had one last final to take. The University was closed; however, the professor sent an email letting us know for anyone able to make it we could come in and take the final.

As I walked the four blocks to campus a slight breeze came in and I saw ice-laden trees begin to sway. Suddenly, from all around sounds of cracking limbs rang throughout the neighborhood. As the soft wind continued, tree branches both small and massive began to fall all around me on the sidewalk. I realized walking on the icy street with the sliding automobiles was a safer bet than the icy minefield overhead the sidewalk.

During the Disaster

Even though my accounts of the frozen stuff only detail ice, severe winter weather comes in many forms. Severe winter weather which can lead to damaging effects or even death of landscape plants include:

  • Large amounts of heavy snow
  • Saturated soils from melt-off combined with trees still laden with heavy snow or ice
  • Bitterly cold temperatures
  • And of course ice

Due to their increase in surface area the larger the limb, the more ice or snow it will accumulate. With snow very often it is safe to use a pole of some sort to knock the powdery stuff off of over-burdened branches. Make sure to lift the branch up, since pulling downward might be a snow-laden limb's literal breaking point. Evergreens with an upright growth habit like arborvitae tend to suffer from bent or broken limbs after a heavy snow cover. Wrapping your arborvitae with two-inch wide strips of cloth every few feet from top to bottom provides the support needed to resist bending and breaking branches.

Should you remove the ice as it accumulates on your trees? Most experts say no, stating that attempts to knock ice off of limbs actually leads to breakage of more limbs and does more harm than good. Not to mention standing underneath large ice-burden tree branches and hitting them with a pole is incredibly unsafe. If you must save your specimen trees, Dark and Hill recommend only removing ice from trees and shrubs no higher than fifteen feet. To remove ice from a limb, very carefully tap the ends of the branch with a stick or pole. Ice should begin to shed off. Do this multiple times to keep excessive amounts of ice from accumulating on specimen plants. Remember if there's ice on the trees then there's ice on the ground. Be careful when walking or just do what I do and just stay inside and drink hot cocoa!

Shoveling and removing snow from walkways and roads can lead to huge mounds of plant crushing snow. Always be mindful of where your small shrubs are and avoid piling snow on top of them. If you know of a spot that often serves as a deposit for the snow plow, avoid planting much of anything there.

As we experienced during the 2013-2014 winter, bitterly cold temperatures can wreak havoc on landscape plants. The best defense against below average temperatures is insulating your plants. Natural snow cover provides some of the best insulation, again avoid shoveling snow on top of plants because shoveling compacts snow, which may crush your plants. In lieu of snow cover raking fall leaves around plants or covering them with row cover or an old bed sheet adds some insulated value.

When it comes to severe cold temperatures, trees are for the most part on their own. In my front yard stands a wonderful thirty-foot tall sweetgum tree which is hardy to zone 5. Yet our past winter was more like that of zone 3, therefore all of the active buds were killed from the deep freeze. It wasn't until late spring that the latent buds popped. Latent buds could be considered the backup plan should something near-catastrophic happen to a tree.

Damage to landscape plants also occurs from ice-melting substances, namely salt. Keeping walkways shoveled during the storm helps to alleviate the need for deicing chemicals. Sometimes ice build-up on walkways is unavoidable and use of a deicer is necessary. Dark and Hill recommend several methods to reduce de-icing damage to nearby plants:

  • Hose off road salts that splash onto trees and shrubs as soon as possible.
  • Avoid planting in areas that will inevitably get hit by de-icing salts.
  • Salt can build up to lethal levels in the soil. As the weather warms you can leach salts out of the soil by irrigating the area multiple times with deep watering's.
  • Apply deicers before a storm arrives. You will also end up using less de-icing material with this approach.
  • If snow and ice are already covering your walkway, shovel and remove as much frozen stuff as possible before applying the deicer.

After the Disaster

After an ice storm, the landscape will likely be breathtaking. But it is a beauty with hidden dangers. Even small limbs can take on hundreds of pounds of additional weight leaving them ready to snap at the slightest breeze. Avoid walking underneath trees burdened by ice and watch your step!

In the days after a winter storm most effort is being focused on snow removal, getting downed limbs and trees out of roadways, and restoring any utilities that may have been lost. To assess your landscape trees it is best to have a certified arborist consult with you on what's worth salvaging and what isn't. Yet, following any weather-related disaster most arborists are busier than ever, so be patient. You can find a list of certified arborists by going to the International Society of Arboriculture's website http://www.isa-arbor.com/home.aspx and search via zip code.

Preparing for Next Time

The best preventative is staying vigilant of forecasted severe weather. By doing so you can install supports for plants that tend toward damage, cover any tender shrubs such as roses, and get those de-icing materials down before the storm hits.

Picking tree species with attributes that allow them to resist winter storm damage is important. Avoid selecting trees that have narrow crotch angles (the angle between the trunk and a main branch) like ornamental pears. Opt for tree species that develop wide crotch angles which have a stronger connection to the trunk, for example oaks.

Be wary of fast-growing trees. These are often notorious for losing lots of limbs during severe weather. Below is a table of tree species recommended for their ability to withstand severe winter weather damage.

Mulch works to insulate the soil to resist the freeze-thaw effects of winter. I have seen newly planted trees completely expelled from their planting hole due to the freeze-thaw of unprotected soil. I prefer organic mulches (compost, wood chips, and shredded leaves) over inorganic mulches (rocks, rubber mulch).

Maintain the health of your tree by having routine visits from a certified arborist. Keeping damaged or dead limbs in check through regular professional pruning will lead to fewer problems down the road.

Have a story to share about a winter that was particularly harsh on your landscape? Feel free to leave your questions and remarks in the comments box below.

Alder, black

Alnus glutinosa

3-7

Bald cypress

Taxodium disticum

4-10

Beech American

Fagus grandifolia

4-9

Blackgum

Nyssa sylvatica

4-9

Catalpa

Catalpa spp.

4-8

Cedar, eastern red

Juniperus virginiana

2-9

Crabapple

Malus spp.

4-8

Ginkgo

Ginkgo biloba

3-8

Hickory, shagbark

Carya ovata

5-8

Hickory, mockernut

Carya tomentosa

4-9

Holly, American

Ilex opaca

5-9

Holly, deciduous

Ilex decidua

5-8

Hornbeam, American

Carpinus caroliniana

3-9

Kentucky coffee tree

Gymnocladus dioica

3-8

Linden, littleleaf

Tilia cordata

3-7

Oak, burr

Quercus macrocarpa

3-8

Oak, red

Quercus rubra

3-8

Oak, swamp white

Quercus bicolor

5-8

Oak, white

Quercus alba

3-9

Pecan

Carya illinoinensis

6-9

Persimmon

Diospyros virginiana

4-9

Spruce, Norway

Picea abies

3-7

Sweetgum

Liquidambar styraciflua

5-9

Viburnum

Viburnum spp.

2-9

Walnut, black

Juglans nigra

4-9

Table adapted from Weatherproofing Your Landscape by Sandra Dark and Dean Hill, University Press Florida

References

Dark, Sandra. Hill, Dean. (2011). Weatherproofing Your Landscape, A homeowner's guide to protecting and rescuing your plants. Gainesville, FL: University Press of Florida.

 

EDIT: This is in response to the comment below from Alex.

If ice is in the forecast then some type of support system would be helpful. Just remember to remove the supports by the time the weather warms up. Here in Illinois heavy snow mostly impacts our upright evergreens. Many homeowners wrap their arborvitae in burlap for the winter to avoid permanently bent or broken branches. However, ice affects all types of trees.

When it comes to preventing ice damage, the first thing to do is observe the branching pattern of your tree once it has lost it's leaves for the winter. Are there a lot of small twiggy branches? This equals lots of surface area for ice to accumulate. Using hand pruners to eliminate unnecessary branches (especially those crossing into the tree) can aid in limiting the amount of surface area ice can accumulate.

Another important factor is pruning for strong branching habit. Small, acute angles of branches emerging from the main trunk often have included bark which is a weak connection. You want to see a wider crotch angle. (which is the angle between the top of the limb and the trunk of the tree) Here is an illustration of desirable and undesirable branching http://friendsoftrees.org/blog/wp-content/uploads/2013/01/Included-bark-Plant-Amnesty-300x156.gif

Pruning is best left during the winter when the tree is dormant. That way the 'bones' of the tree are revealed. Plus, once spring comes the tree will be able to focus energy on sealing the wounds.

During the disaster as the article says you can head out to periodically knock ice off the small tree branches, but that can be risky to you during a severe ice storm. Some recommend pouring warm (not hot!) water on the branches.

Either way, proper pruning is the best preventative to reduce the risk of limb breakage during an ice storm. (Plus selecting trees that aren't as susceptible) Here is a link to an article that provides more information http://web.aces.uiuc.edu/vista/pdf_pubs/icestorm.pdf

I have seen some beautiful weeping Japanese maples. Hope yours fares well this winter! Thanks for reading!


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COMMENTS



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Thank you so much for this timely advice!
by Lynda Boomer on Tuesday 11/11/2014

Glad it was helpful. Thank you for sharing!
by Christopher Enroth on Wednesday 11/12/2014

Great article -- I'm actually messaging from SC due to researching how to prevent more damage to my weeping laceleaf maple. This past winter, we were hit by a freak ice storm that left us encased in 1.25" of ice. A branch was ripped off, and I am trying to figure out how to avoid this next time. My local garden center suggested i pull the limbs in closer to the trunk with foam wire tie, i think some sort of support system from below (maybe a stake system). How to y'all deal with this? I would assume it's similar to a snow load. Thanks!
by Alex on Thursday 11/13/2014

Alex - I added my reply at the end of the article. Turns out there is a word limit in these comment boxes. Thanks!-Chris
by Christopher Enroth on Wednesday 12/3/2014