Green Giant Arborvitae Discoloration - Ask Extension
We planted 3 Thuja Plicata (green giant) arborvitae 5/28/2022.
They have been fine until this spring. I noticed the discoloration after the hard fro...
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Green Giant Arborvitae Discoloration #871379
Asked June 03, 2024, 5:08 PM EDT
We planted 3 Thuja Plicata (green giant) arborvitae 5/28/2022.
They have been fine until this spring. I noticed the discoloration after the hard frost we had in late April this year. My local nursery suggested a low nitrogen fertilizer, I chose Espoma Evergreen-Tone and followed the directions. This was done 1 month ago.
The discolored leaves are not brittle and new growth is occurring past the discoloration.
The trees all have this same odd color. I cannot see any others in my area that look like this.
Any suggestions on what happened and if there is anything else I can do would be most welcome.
Washtenaw County Michigan
Expert Response
Hello,
This looks to me like sunscorch, which can happen when moisture levels are not kept consistent. It really prefers moist soil and some shade. I recommend making sure the trees are consistently watered and kept mulched. I would not recommend pruning out discolored growth. As new growth fills in you will not notice the discoloration. These trees are vigorous growers with few problems and will respond well to the added moisture. Here is more information: https://plants.ces.ncsu.edu/plants/thuja-plicata/
Thank you for contacting Ask Extension.
Ruth
This looks to me like sunscorch, which can happen when moisture levels are not kept consistent. It really prefers moist soil and some shade. I recommend making sure the trees are consistently watered and kept mulched. I would not recommend pruning out discolored growth. As new growth fills in you will not notice the discoloration. These trees are vigorous growers with few problems and will respond well to the added moisture. Here is more information: https://plants.ces.ncsu.edu/plants/thuja-plicata/
Thank you for contacting Ask Extension.
Ruth
Thank you for the information.
The tag on my tree said Thuja Plicata (I saved it) but when I look up Green Giant Arborvitae it says Thuja Standishii x Plicata. It is a hybrid.
The trees I have do not have any pine cones or buds and they do not look like the tree in the link’s video.
I believe they are arborvitae. They have been consistently watered and are two years old.
No problems existed until a hard frost in April. Sun is not strong enough to scorch that early in the season.
Would you be so kind as to reconsider my question with the new information?
Thank you !
On Jun 4, 2024, at 1:58 PM, Ask Extension <<personal data hidden>> wrote:
Hi Cathy,
Ruth sent me your question for reconsideration. I believe Ruth was partially correct, and the cause is winter burn. Winter burn occurs during warm winters that stimulate evergreens to photosynthesize when the ground is frozen. The tree loses moisture during the photosynthesis process, and can not uptake water to replace the moisture lost because the ground is frozen. When this occurs, the plant is suffering from drought stress and that doesn't become apparent until spring temps (or in this case, a hard frost). You can read more about winter burn in the article at the link below:
https://hort.extension.wisc.edu/articles/winter-burn/
You are already doing everything recommended for it's recovery. The reddish-brown leaves will eventually shed, or be obscured by new growth. And keeping it watered during times of no rain (like you are doing) it always best.
Please feel free to reach out if you have any questions!
Thank you,
-Julie
Ruth sent me your question for reconsideration. I believe Ruth was partially correct, and the cause is winter burn. Winter burn occurs during warm winters that stimulate evergreens to photosynthesize when the ground is frozen. The tree loses moisture during the photosynthesis process, and can not uptake water to replace the moisture lost because the ground is frozen. When this occurs, the plant is suffering from drought stress and that doesn't become apparent until spring temps (or in this case, a hard frost). You can read more about winter burn in the article at the link below:
https://hort.extension.wisc.edu/articles/winter-burn/
You are already doing everything recommended for it's recovery. The reddish-brown leaves will eventually shed, or be obscured by new growth. And keeping it watered during times of no rain (like you are doing) it always best.
Please feel free to reach out if you have any questions!
Thank you,
-Julie
