Husker Hort

A Nebraska View of Horticulture

Keeping Evergreens Ever Green

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Winter Desiccation Damage on Dwarf Alberta Spruce

Winter Desiccation Damage on Dwarf Alberta Spruce

Good-bye to 2014 and hello 2015. It’s been an exciting year. Above average moisture this spring and summer had most of our trees full with leaves and fruit and our gardens bursting with produce. With this year coming to an end, do you know what it takes to make sure your evergreen trees and shrubs stay in good spirits into the New Year?

Winter is often an overlooked season when it comes to watering in the landscape. Plants may be dormant during the winter, but they still loose water through their stems, crowns, and in the case of evergreens, their leaves. Desiccation injury happens when the plants can’t replace the water that is lost during the winter. The cause is often dry or frozen soils where the water isn’t available for uptake by the plant. High winds, dry air, warm temperatures, and reflected heat from buildings can all play a factor in the amount of water lost by plants.

Not all plants are susceptible to winter desiccation. Common symptoms of desiccation include brown, damaged foliage on one side of the plant. Damaged foliage is often found on the south side due to reflected heat or the northwest side caused by wind exposure. This often results in plants having areas of yellowish/tan colored leaves that are the most noticeable come spring. Woody evergreen plants with shallow root systems are usually the hardest hit. Spruce, fir, pine, arborvitae, yew, Oregon grape-holly (Mahonia), holly, and boxwood are some of the more common evergreen plants that would benefit from supplemental winter irrigation during extended dry seasons

Providing supplemental irrigation during the winter months can help sensitive plants make it through the winter a little less stressed and with less winter desiccation injury. Young trees, shrubs, and all evergreens can be irrigated as long as the soils are dry, not completely frozen, and the air temperatures are above 40 degrees Fahrenheit. Want to apply supplemental water, but short on time? Focus on those trees that are growing in sunny, exposed locations, focusing on the south side of the tree first. Apply water using a slow running sprinkler or a trickling hose. Root feeders or other deep watering devices often do not water thoroughly enough and can place the water below the root zone of the tree. Aim to get the top 8-12 inches of the soil moist and apply the water slowly enough to let it soak in and not run off. Be sure to allow enough time for the water to soak in and avoid freezing around the plants’ stem or crown when the temperatures drop overnight. If we remain dry this winter, one or two deep irrigations per month might be needed.

Antitranspirants are another method that can be used to prevent desiccation. Antitranspirants, like Wilt-pruf, form thin films on the foliage and can minimize the water that is lost by the plants. They are commonly used on evergreen conifers and broadleaf evergreens that are growing in stressful sites in the winter. Select the right product for the plant species you are applying it to, there can be some toxicity issues, and ALWAYS read and follow all label instructions. Most products should be applied every six weeks starting in mid to late November through mid to late February. Apply enough of the product that the plant is thoroughly covered, but not so much that they become sticky or the needles become stuck together. To keep the product from ruining your favorite sprayer, be sure to have some warm soapy water nearby to clean the sprayers out immediately following the application.

It’s time to ring in the New Year with happier, healthier evergreens.

Upcoming Programs:

Extension Master Gardener- Two training sessions will be held at the Nebraska Extension in Hall County meeting rooms in Grand Island. Session 1: Tuesday evenings, February 3 through March 10, 6:00 to 9:00 PM. Session 2: March 16, 18, 20, 23, 25, and 27 from 9:00 a.m. to 4:00 p.m. Please contact Elizabeth Killinger, 308-385-5088, prior to January 9 with which Extension Master Gardener training session you are interested in attending. More information, updated schedules, and a brochure can be found at http://hall.unl.edu

For more information contact Elizabeth Killinger at elizabeth.killinger@unl.edu, 308-385-5088, on Facebook, Twitter, her blog at https://huskerhort.wordpress.com/, or visit the University of Nebraska-Lincoln Extension website: hall.unl.edu.

PDF version: 12-28-14 winter evergreen care

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Author: Elizabeth Killinger

A Nebraska Extension Educator out of Hall County with a focus in horticulture and sustainable landscapes.

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