Brown arborvitae

Asked October 19, 2018, 10:32 PM EDT

Hi, I’m wondering if you can tell me what’s wrong with my arborvitae and if there’s anything I can do. Almost all of them are having orange dead spots and are getting really thin. Thanks Ryan Herington

Hennepin County Minnesota

3 Responses

Good question. In fact, this afternoon I noticed various brown spots in my own arborvitae. I do keep track of things related to gardening and have seen this situation off and on over the past ten years. Extensive browning of large, concentrated regions of the tree would be cause for concern. Your pictures, however, show patches of brown needles. If this extensive browning was in early spring, then winter burn would be the cause. If it is seen in late spring/early summer, then some type of fungal disease would be suspect. However, I assume that what you are observing has developed over the past month or so. That was the case with my own arborvitae. What is happening to your arborvitae is most likely normal needle drop. It is very common in arborvitae as the growing season winds down. Water your arborvitae well and frequently until the ground starts to freeze. My guess would be that come next spring, your arborvitae will be back to their normal selves. See the following:

Good Luck!!

Thanks for the response, I appreciate it. Wondering if you can tell me when and what you would recommend for fertiizing my evergreens. Thanks again

You should plan on fertilizer early next spring. The type of fertilizer and its amounts are best determined after you have a soil test done. This can be done at the University of Minnesota Soil Testing Laboratory:

The following publication by the University of Minnesota has recently become available and should provide you all the necessary information:

Good Luck!!