(Question)

The tree on the far left is noticeably different in color compared to the others. Is this normal?

Clay soil with southern sun and shade exposure.

The trees were planted at the beginning of May 2022.

I’ll admit, I fell behind on watering this past week during the heat wave.

This is my first time caring for emerald cedars.

I’m wondering if this is just drought, or if it could be something more complicated.

Thank you in advance.

(Answer)

Thank you for asking this question about your Emerald Cedar tree (Thuga occidentalis ‘Smaragd’). I am sorry that one of your trees is not doing well. Unfortunately, you are not alone. The Toronto Master Gardeners have often been asked questions about Emerald Cedars that are not thriving.

The Emerald Cedar trees are prone to being quite temperamental especially about transplant shock, the soil they are planted in, and the quantity of water they receive. They need a lot of water – but not too much otherwise they can get root rot. They like their soil to have organic matter. They need fertilizing – but not too often, and definitely not in the Fall before they go into dormancy. They are also prone to some insect invasions (that can usually be controlled by a strong spray of water).

It is not unusual for the tree that is at the end of a row of trees to start showing stress even though the rest of the hedge is still looking good. This is usually because of a change in soil at the edge of the bed. Your clay soil (the dominant soil of Toronto) may be the issue. Was the edge of the bed more prone to compaction? Does the edge of the bed have less organic matter than the rest of the bed? If you have an irrigation system, does the water reach the edge of the bed? Alternatively, is water pooling at the edge and not draining well? One more thought: is there a chance that the edge of the bed is where a dog is urinating? Most nurseries will replace a tree within a year if it is not thriving. My suggestion would be to take a photo of the cedar and take it to the nursery where you purchased the trees and ask for a replacement.

For a more details on these issues, along with general care of cedars, please go to previous Toronto Master Gardener answers on Emerald Cedars:

Browning emerald cedars

Cedars browning inside

Cedars turning brown

Here is also a link to some alternative trees to the Emerald Cedar that are more adapted for our growing area:

Alternatives to emerald cedars