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Winter Affects Our GardeningMaster Gardener Scoop – January 18, 2017

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Winter Affects Our Gardening

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By Will Summers,

Master Gardener

We do not have a choice but to accept the weather, and now winter is well upon us. Weather, as well as our health and politics, seems to be one of the most talked about of subjects these days. Everyone has their own opinions of likes and dislikes regarding winter weather and especially the snow and ice. Home gardeners have mixed feelings regarding the effects of cold weather, especially types of precipitation on landscapes and gardening. Winter may affect gardens in three ways: freezing temperatures, moisture or types of precipitation, and soil chemistry.

Freezing temperatures penetrate soil deeper without an insulating blanket of snow. Freezing temperatures damage sensitive roots and bulbs. Freezing also drives insects and their larva deeper and delays some insect lifecycles. In some cases, heavy soil freezes are thought to reduce the number of lifecycles on some grub species such as Japanese beetles and June beetles.

Sunscald dries evergreen leaves and needles usually on the southwest side of the tree or bush. This is recognizable but not always treatable. A protective wrap of burlap and wood stakes may shield smaller evergreen shrubs such as arbor vitae, but larger shrubs and trees must be monitored and sprayed with an anti-desiccant solution. Just remember to remove any wraps before the advent of warm temperatures.

While heavy snow may insulate the ground, snow also weighs down branches of shrubs and some trees and should be brushed off before breakage or permanent misshaping. Ice storms are particularly damaging to trees causing limb breakage and sometimes even uprooting. Heavy ice and snow may not break a branch, but may leave permanent bending that severely misshapes the plant. Be sure to monitor wet snow and ice accumulation on any prized woody species, and be prepared to knock off any accumulations as necessary.

Many people do not realize that vegetation needs moisture in winter, and many plants suffer moisture stress in winter. Evergreens such as pines, holly and arbor vitae continue to transpire water in winter. The roots ability to absorb water is reduced when the soil is deeply frozen. Close mowed lawns and finely tilled flowerbeds lose the most soil moisture, while maintaining a leaf layer or composted plant materials conserves soil moisture. There are two ways to prevent winter moisture stress: make sure trees have sufficient water before the ground freezes in the fall, and plant evergreen trees and shrubs away from areas likely to be moisture-stressed in winter.

The concept of "Don't Eat Yellow Snow" applies to the impacts that cause plant growth adjacent to sidewalks and roadways to suffer in winter. Be aware that dogs and even cats spraying or marking their territories will affect exposed vegetation especially hard in winter. This appears as a browning of leaves and needles at any prominent location close to the ground.

However, de-icing fluids, antifreezes and other components used to keep people moving in winter also severely damage landscapes. Often, salt damages lawns and evergreens immediately adjacent to heavily maintained thoroughfare in winter. The damage even extends to mature trees such as white pine that grow 40 feet from an adjacent salted roadway.

Use de-icing chemicals with foresight for the way water drains off your intended icy target. Substitute with less damaging de-icing material that contains calcium chloride or calcium magnesium acetate(CMA) instead of the common rock salt used in many cheaper brands. Consider using more inert, less chemically reactive materials such as sand, sawdust, cat litter or even birdseed.

Winter influences home landscapes by temperatures, moisture and chemistry. All forms of winter damage appear as brown, red, or discolored foliage. Sometimes winter damages only a year's foliage. It is important to remove all winter-killed plant material, but please wait until after the new spring growth has occurred.

For more information regarding winter gardening, please contact your local University of Illinois Master Gardener, your local Extension Office at 618-327-8881 or your public library. Please consider joining Master Gardeners at any of the scheduled Master Gardener training classes beginning January 24th in your area.