Q: I recently noticed that some of my evergreens have become discolored. Should I be concerned?
A: It is normal for the foliage of some evergreens, such as arborvitae (Thuja) and boxwood (Buxus), to change color in cold weather. The different color of the foliage in such species is not indicative of a pathogen or cultural disorder; it is a normal response to winter temperatures.
Species that are known to change color in cold weather include:
- Arborvitae (Thuja): Foliage can develop a bronze, yellow-green, or brown tint.
- Boxwood (Buxus): Foliage may darken to burgundy or change to a brownish or yellowish-green shade in the winter.
- Holly (Ilex): Some species may develop a yellow cast in cold weather.
- Juniper (Juniperus): Depending on the species, foliage may develop a bronze, purple, or yellow-brown cast in cold weather.
- Rhododendron (Rhododendron): Some evergreen species develop a purple, brown, or yellow cast in cold weather.
In any of these species, the observed color change can vary from plant to plant and from year to year.
In species other than those listed above, significant cold-weather discoloration may indicate damage or disease. Please contact Plant Information Service at (847) 835-0972 or firstname.lastname@example.org for additional information.