Spring Plant Care For Winter Tree Damage in Wisconsin

Posted: 2025 | Plant Health Care | Summer | Tree and Shrub Care

Despite a distinct lack of snow this year, winter tree damage has manifested in an abundance of ways this spring. We’ll cover some of the specifics that we’ve seen in past springs, but many of these plant health care issues are common any time there is an open – or snowless – winter. They were exacerbated this year as it was the second open winter in a row, and was preceded by a very dry fall.

Many needle evergreens showed brown patches or dead branches, including:
- Western arborvitaes
- ‘Green Giant’ hybrid arborvitaes
- Some juniper varieties
- Scots pines
- Limber pines
- Austrian pines
Many broadleaf evergreens showed signs of winter tree damage, particularly pachysandra groundcovers, but also including:
- Boxwoods
- Hollies
- Vincas
- Euonymus
Trees suffering from pre-existing conditions had portions of their crowns die, including:
- Pines with Diplodia tip blight infections
- Spruces with Cytospora branch cankers
- Magnolias with magnolia scale damage
- Japanese tree lilacs with verticillium wilt infections
- Maples with girdling (strangling) root conditions
There were several half-hardy trees that showed signs of winter tree damage as well, including:
- Japanese maples
- Magnolias
- Some redbud varieties
- Some hydrangea varieties
- Peaches
- Ornamental pears
Some perennials were also lost or came up weaker than they usually do. The damage was not limited to small specimens either, as some larger trees showed branch and/or crown damage as well, including:
- Sugar maples
- Silver maples

The Dangers of an Open Winter

An open winter, also known as a snowless winter, is one that involves little to no snow cover. While this was once extremely rare for Wisconsin winters, it has become less so due to changing climate trends, as evidenced by back-to-back open winters in 2023–2024 and then 2024–2025. The ramifications of winters like these were presented at the Wisconsin Arborist Association Annual Conference in February 2022.

The lack of insulating snow cover allows faster and deeper frost penetration during polar vortexes, which can lead to severe winter tree damage and even kill some tree roots. While we’ve long known this was a problem for half-hard trees like magnolias or Japanese maples, we’ve recently learned that it can be very significant for native trees as well. Even these may not be able to adjust quickly enough, causing damage in their root tissues.

Spring 2025 was surprising in that the damage seen was much more than the previous, despite it also following an open winter. Ensuring that trees receive 1” of water per week is imperative to enable regrowth. In fall, measures to help trees replace or build new feeder roots can compensate for this stress and damage. In addition to pruning out the damage, which not only helps aesthetics but restoration as well, these measures include: