Cedar Trees

(Question)

Our Cedar Trees are about 30 years old and at least 20 ft. high. They have had a tough summer and show signs of stress. Would it be a good idea to put some acidifier down before winter? Also would they benefit from ongoing application of our coffee grouts and tea leaves?
Comments would be appreciated.

(Answer)

A few issues to consider are, whether these mature cedars have been in your care for these thirty years and if so, what maintenance have they received? A common problem, for instance, is lack of water, and often compacted soil combined with this, contributes to stress. Less frequently occurring but also a stress factor is too much water or flooding, which can cause root death.

With regard to soil pH, Thuja (Cedar) prefer neutral soil and may actually need lime amendment if the existing soil is too acidic but only testing can determine the current pH.

Likely, a combination of soil compaction, which occurs after only a few years and lack of water during our extreme heat summers is the main cause of decline. Correct cultural practices, including soil amendment, mulching and pruning are key to thriving cedars, especially as they mature.

An excellent overview of cedar care can be viewed here:

https://www.torontomastergardeners.ca/askagardener/pruning-and-fertilizing-cedar-hedge/