Arborvitae Care - Ask Extension
We have arborvitae that was planted in the early 1960's. Generally they are healthy but some show signs of age with having thing spots. Is it worthwhi...
Knowledgebase
Arborvitae Care #877965
Asked July 19, 2024, 5:07 PM EDT
We have arborvitae that was planted in the early 1960's. Generally they are healthy but some show signs of age with having thing spots. Is it worthwhile to feed them? Is there anything that can be done for arborvitae that are this old? They are only about 8 feet in height and about 3-4 feet in diameter. They are used instead of a fence but we are starting to see through them. What is your recommendation?
Marion County Oregon
Expert Response
Dear Cheryl,
Thank you for contacting Ask Extension about your arborvitae. Normal shedding of leaves usually occurs in the inner portions of the foliage. From your email, it sounds like the trees are browning randomly throughout. If this is not correct, please let me know.
Arborvitae frequently develop browning for a variety of reasons, but it is often very difficult to determine a single cause. Their expected life span in an urban environment is 40 to 60 years, and it may be that yours are approaching the end of their life.
Arborvitae are prone to root rot diseases particularly if the soil is compacted and/or poorly drained. They need rich soil and slow, deep irrigation during periods of high heat or drought (including in winter.)
Trees need a minimum of one-inch of water per week, year-round. This is difficult to do with a large hedge. To extend the life of your hedge, I suggest irrigating across the entire root zone using a slow drip. The water needs to penetrate at least 2 inches deep into the soil.
To improve the soil, apply up to one-inch of finished compost over the entire root zone area. Top that with 3 to 4 inches of woodchips which will further protect and enrich the soil.
All trees grown in a landscape need to be fertilized. Without the litter of a forest floor, they cannot get proper nutrients for their size and longevity. This is normally done in spring so I do not recommend doing it now. Fertilizing may stimulate new growth which may not have time to harden off before cold weather returns.
This article may provide some useful information:
https://www.statesmanjournal.com/story/life/2018/01/29/whats-behind-die-back-brown-patches-arborvitaes/<personal data hidden>/
You might consider asking a certified arborist to take a look at your hedge. Often they will do this at a nominal or no fee. You can find a qualified arborist in the Homeowners tab at the following link:
https://pnwisa.org/page/choosing-a-qualified-arborist
I hope this information is useful. Please write again whenever you have a gardening question.
Thank you for contacting Ask Extension about your arborvitae. Normal shedding of leaves usually occurs in the inner portions of the foliage. From your email, it sounds like the trees are browning randomly throughout. If this is not correct, please let me know.
Arborvitae frequently develop browning for a variety of reasons, but it is often very difficult to determine a single cause. Their expected life span in an urban environment is 40 to 60 years, and it may be that yours are approaching the end of their life.
Arborvitae are prone to root rot diseases particularly if the soil is compacted and/or poorly drained. They need rich soil and slow, deep irrigation during periods of high heat or drought (including in winter.)
Trees need a minimum of one-inch of water per week, year-round. This is difficult to do with a large hedge. To extend the life of your hedge, I suggest irrigating across the entire root zone using a slow drip. The water needs to penetrate at least 2 inches deep into the soil.
To improve the soil, apply up to one-inch of finished compost over the entire root zone area. Top that with 3 to 4 inches of woodchips which will further protect and enrich the soil.
All trees grown in a landscape need to be fertilized. Without the litter of a forest floor, they cannot get proper nutrients for their size and longevity. This is normally done in spring so I do not recommend doing it now. Fertilizing may stimulate new growth which may not have time to harden off before cold weather returns.
This article may provide some useful information:
https://www.statesmanjournal.com/story/life/2018/01/29/whats-behind-die-back-brown-patches-arborvitaes/<personal data hidden>/
You might consider asking a certified arborist to take a look at your hedge. Often they will do this at a nominal or no fee. You can find a qualified arborist in the Homeowners tab at the following link:
https://pnwisa.org/page/choosing-a-qualified-arborist
I hope this information is useful. Please write again whenever you have a gardening question.
