Some trees have a hard time making it through a winter. This is true whether they are in the open, in a new development, on an acreage, or protected in an old neighborhood. Winter sunscald and frost crack can be a real problem. Steve Schwab, retired City Forester, City of Lincoln Parks & Recreation Department, had a question about frost crack and sunscald at a meeting of the Lincoln Garden Club 6 years ago. I realized then that I had not written about this so I asked him to describe what they are, how to prevent them, and what trees are the most likely to be damaged. I am repeating his response as it is still applicable today. Last week I outlined Steve’s recommendations for dealing with frost crack and sunscald. Also about protecting thin barked trees during the winter. Today I have written about winter protection of evergreen trees and shrubs.



          I asked Steve about winter protection of arborvitaes and evergreen trees like my DWARF ALBERTA SPRUCE, UMBRELLA SPRUCE, and UMBRELLA PINE, and on shrubs that do not drop their leaves such as HOLLY, RHODODENDRON, and BOXWOOD, using Wilt-Stop or Wilt-Pruf. Steve replied to my question as follows:

          “You may use Wilt-Stop or Wilt-Pruf on shrubs outside that keep their leaves, evergreens, and arborvitaes, but it is important to wait until the plants have completely hardened off, whereby the moisture in the foliage retreats to the root system for the winter. We suggest you wait until after the first part of December to be sure they are dormant and completely hardened off.”

          “You may spray Wilt-Stop or Wilt-Pruf anytime as long as the spray does not freeze on the foliage while applying and for at least a couple hours afterwards. If you put the mixture on too early in the season before it has completely hardened off and there is moisture in the foliage, you run the risk that a deep freeze can occur and that moisture in the plant cells can freeze and burst the cells causing damage to the plants.  If Wilt-Stop or Wilt-Pruf has been applied too early before hardening off, we get the blame for an act of nature.”

          For those who are not familiar with Wilt-Stop or Wilt-Pruf, these products contain wax that coats the needles of evergreen and arborvitae trees, and the leaves of shrubs that do not drop their leaves, so they do not winter burn or dry out and die. The needles on evergreen trees and the leaves on shrubs that do not drop their leaves, continue to perspire all winter long. However, because of the frozen ground, they can not take up moisture to replace the lost water, and thus dry out.

          All the cut Christmas trees at one garden center here in Lincoln are opened, fluffed up, and then sprayed with Wilt-Stop within 24 hours of receipt. Because of this process the needles stay green longer when the tree is taken inside to a warm and dry environment. In a home or office environment they lose lots of water and can dry out very fast. Wilt-Stop and Wilt-Pruf can be purchased at any garden center in a small ready-to-spray (RTS) container or in a concentrate that is mixed with water and applied with a small pump-up sprayer. If you purchase a cut evergreen tree, ask if they have sprayed it. If they have not, take it home and spray with one of the anti-desiccants before taking inside.

          I also spray my small evergreen trees outside, my RHODODENDRONS, and my BOXWOOD hedge on a warm day (40 degrees F. or above) just before Christmas, and then again about Valentine’s Day. (As you can tell from my writings I like Holidays as a reminder for what to do when.) When I am outside I use a hose end sprayer if at all possible, because I have so many shrubs and small trees to spray. I drain the hose and put it to bed again. If not possible I use a small pump up sprayer and mix the solution using warm water so it does not freeze before I finish.

          If we have a very cold winter with lots of wind and snow, or we have rain that washes the wax off, you may need to also spray in mid January. Since these products are waxy, be sure and follow the manufacturer’s recommendations on how much to use, and how to clean your sprayer after use so the wax does not dry inside the sprayer, or in the spray head and clog all the parts. After use, I rinse my sprayer with soapy water a couple times and then rinse with warm water a couple times.

Copyright 2014