Late Winter Bronzing of Evergreens-Is it Normal?

What is “winter bronzing”? While approaching the end of winter, some of your favorite evergreens may appear to take on a bronze appearance. You may be wondering. “Is this normal or is my plant dying?” Changing foliage color is a normal phenomena that affects some evergreens near the end of winter while seasons are transitioning. Freezing temperatures, followed by a warming trend, longer hours of sunlight, then more cold can trigger foliage to discolor. The color change is a reaction to low temperatures, winds and sunlight, causing mild desiccation of the needles or leaves, allowing the underlying colors to show through. This dulling of green foliage is more pronounced on plants that receive more sunlight. The result is commonly known as “winter bronzing”. The longer the ground is frozen and the more water that is evaporated from the plant than it can take in, the more pronounced the foliage will appear to turn from green to brown, bronze, or even orange or purple. This process is similar to why deciduous leaves change color in the fall. While the tree is going dormant for the winter months, chlorophyll production subsides and the true underlying colors of the leaves are revealed. 

Winter Bronzing of Evergreens

When can I expect my trees to look more normal? Once the temperatures rise and new growth is stimulated, the foliage will turn back to a more vibrant green. Broken or dead branches are different in that they are completely dried out and brown. Those branches should be pruned off the tree in late winter/early springtime to prevent any further damage. Any falling or divided tree leads can be arbor tied to secure them and encourage upright growth. Split branches can also be arbor tied together, and if caught in time the cambium growing layer of the tree can mend. In the photograph above, the center upright Western Arborvitae are displaying signs of bronzing with no evidence of  any completely browned or broken branches, both indications of a normal and healthy tree.

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