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Sally Cunningham: Extreme weather and your plants

The extreme weather that slammed us early this month caused suffering and endangered many people and animals. It was dramatic and easy to remember.

In the plant world, damage usually shows up more slowly, but that kind of weather is equally destructive. High winds, record freezing temperatures, and drastic temperature changes wreak havoc on plants. You may not notice it until spring, and then look for immediate reasons those plants look sickly or dead.

Most likely, the reasons for many – even most – plant failures next season are the weather patterns of winter, 2019.

Northtowns, Southtowns, Buffalo … Whose yards took the worst hits?

This answer is unclear and variable because weather events affect different plants. And how the plants are affected is also variable: The damage depends upon the intensity, duration, and the order in which the weather changes occur.

Here are some examples:

Tree breakage and blow-overs: You were smart if you hired a certified, qualified arborist before this season, as I did. When tree canopies are properly lightened and dead branches removed, you will not see many branches falling.

Trees with overcrowded canopies are most likely to blow over, as wind grabs them like sails. Trees that are wounded or damaged by construction, and trees with poor root systems in poor soil are most likely to be damaged.

Wind injury to evergreens: Wind damages evergreens (such as pines, spruces, rhododendrons) because these plants do not drop their leaves (or needles). They continue to lose moisture through the leaves. Yet the ground remains frozen, so they cannot take up moisture to replace the loss.

It is worse for plants that were recently planted or went into the winter dehydrated. Watch for browning and dead branches especially on the side hit by the wind.

Flooding and standing water: It’s interesting to read textbooks that show how every single plant has a specific level of tolerance for standing in water and water-logged roots.

Black and green ash, red-osier dogwood, red maple, and willow trees are highly tolerant. American beeches, crabapples, flowering dogwoods, many elms and oaks, ninebarks, redbuds, and paw paws are among the many that do not tolerate standing in water.

It depends upon how long the roots are saturated, as explained in “Diseases of Trees and Shrubs,” by Wayne A. Sinclair, Howard H. Lyon and Warren T. Johnson (Comstock Book, first edition, Cornell University Press).

Similarly, some perennials die and others survive after flooding. Lawns also suffer increased compaction, weed seed influx, and diseases after water saturation.

Correcting poor drainage is critical for many plants’ survival.

Injury from extreme freezing: Each plant has a tolerance level for freezing temperatures during dormancy, but it depends upon how well the plants have acclimated before the freezes occur. In other words, if plants (perennials or woody plants) cool down and go dormant gradually, they can handle extreme temperatures better.

This season some severe temperatures hit some plants that were not well acclimated. Also some plants unfortunately warmed up just in time for the most severe temperatures.

Other things may have hurt your landscape and garden this winter: salt, snow plow activity, desperate deer and rabbits, ice crashing off roofs onto shrubs, and ice-coated branches breaking.

What to do?
If valued trees blow over, you have a very small window of opportunity to right them and re-pack the root systems. Call an expert arborist. You have more time for cracked trunks and broken branches, but also call a Certified Nursery & Landscape Professional (CNLP) or arborist. (It’s generally pruning time now anyway).

In the perennial and shrub beds, look for any heaving that has exposed roots: Thaw out some compost and pack the roots, pressing them down to prevent desiccation. Keep mulch in place and refresh what has blown off. Stay off wet or frosted garden soil and grass.

Most of all: Observe. Wait. Contact professionals and plan the repairs. We’ll know better what happened in a few weeks.

Sally Cunningham is a garden writer, lecturer and consultant.

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