University of Illinois Extension

Preserving Evergreens During the Winter

Just finished putting the finishing touches in your landscape? The new spruces, pines, yews, arborvitae or junipers look great. They make a nice screen, wind break or specimen plant. The color is just right. Now the question is - will they stay looking good? Will they survive the winter?
James Schuster, a University of Illinois Extension horticulture educator based in Cook County, has a few helpful hints.

evergreen“Winter can be harsh,” he said. “Long cold periods with drying winds can help dehydrate the new plants. Plants in newly built subdivisions are even more prone to being dehydrated through the winter than those planted in neighborhoods with many mature plants. Since evergreens, both needle and broadleaf, maintain live foliage through the winter, the foliage continues to loose moisture even when frozen. If the water loss is too great, the needles or leaves will turn brown as they dehydrate and die.”

Schuster said there are several possible cultural practices that can be tried.

“First make sure there is plenty of soil moisture before the ground freezes,” he said. “If there has not been sufficient rain, water. Water the planting hole as well as a couple of feet of the surrounding soil. Avoid over-watering. Over-watering can drown tree roots adding to winter kill.”

Consideration should also be given to applying an anti-desiccant spray.

“Make sure to read the label,” he said. “Use the winter label rate at the recommended temperature. These products vary in their longevity and effectiveness on the plants. Usually a second and sometimes a third application later in the winter are required. These products when applied correctly can sometimes make the difference on plant survival as well as appearance the following spring. Do not apply the winter rate till the plants are dormant.”
Another way to reduce dehydration is make a screen to partially block the wind. Use sturdy stakes that are a couple of feet longer than the plant is high. Place the stakes in the round before the ground begins to freeze.

“How many stakes depends on whether you want a “V” shaped screen or a flat screen as well as how many evergreens were planted,” said Schuster. “Once the ground begins to freeze, nail, staple or tie a material like burlap, cheese cloth-like material or even snow fencing to the stakes. If using the “V” shaped screen around an individual plant, the bottom of the “V” stake is directly west of the plant. The other two stakes are to the southeast and to the northeast of the plant. The entire east side of the plant is left open.”

Schuster cautioned against completely wrapping the plant with the protective material. This barrier is to reduce the flow of wind through and around the evergreen. It is not suppose to stop the wind entirely. You need to make sure light reaches all of the plant, therefore do not situate the screen so that it touches the plant.