Winter Injury Observed in Ornamental Plantings

Common Symptoms

Extension educators and staff across the state often receive reports of various species of evergreens with brown tips, dieback, and possible fungal infection. Plants commonly reported with winter injury symptoms include arborvitae, cypress, holly, rhododendron, boxwood, pachysandra, and mahonia.

For many of these plantings, the problem may have started last summer and fall, when drought conditions often occur. Pennsylvania experienced drought in both 2024 and 2025, especially in the southeastern part of the state. Trees and shrubs that have been planted in the last 1-3 years are more susceptible to drought than established trees and shrubs. Further, drought-stressed plants are more susceptible to winter injury and to other stressors, such as fungal infections and increased insect pressure. Drought conditions combined with windy and cold winter weather lead to desiccation (water loss) in evergreen plants, which causes browning and death of plant tissue. Leaves and needles lose water during the winter, especially if they are in locations with a lot of wind or sun. The plants can't replace the water when the ground is frozen during the winter, so the leaves or needles dry out and turn brown and entire plants can die. Broadleaf evergreens such as rhododendron can have curled up leaves or marginal leaf browning.

Management Options

Reducing stress on plants is one of the best management options. Planting in protected areas and watering during extended dry periods can help reduce stress. Deep waterings are better than frequent, shallow waterings. For plants younger than 5 years, consider watering into late fall – before the ground has frozen – so the plants have adequate water going into the winter. A 3-4 inch layer of mulch helps to conserve moisture and insulate the ground but be careful not to cover the root flare of trees and shrubs. In cases of windbreak plantings, be sure to use species that are suited for high-wind areas. Some hybrid evergreens, such as Leyland cypress, are shallow-rooted and fast-growing and do not have the longevity that other species offer.

If plant tips or limbs are brown, they will not recover. Check whether branches are still alive by scraping away a small area of bark to look for healthy green tissue. Dead plants should be removed. Prune and remove completely dead branches on woody plants showing dieback. Pruning helps stimulate new growth, reduces areas where fungi can take hold, and removes inoculum if an infection is already present. The evergreen groundcover, pachysandra, is more susceptible to Volutella blight when plants are stressed by drought and winter injury. Thinning beds to improve air circulation will reduce disease.

Fungicides can be used, but they will only protect new growth. Examples of fungicide active ingredients include copper, chlorothalonil, and mancozeb. Read the label and apply according to the instructions.