Hi, I planted 8 new emerald cedar trees 3 weeks ago. One of them looks like is dying. Im at North York (Islington/Steeles) so I guess that’s zone 6? The native soil type was I guess clay or sand.. I can’t tell. I did add 3 yards of triple mix soil. Watered daily 3-5mins each tree.
Thank you for contacting the Toronto Master Gardeners about your emerald cedars (Thuja occidentalis ‘Smaragd’). Unfortunately I cannot tell much from your photo since it is a bit blurry and too far away, but that tree is clearly in distress! There could be several reasons for this including over or under watering, insects, disease, and problems caused by how the tree was planted.
Emerald cedars prefer moist, well-drained soil, in full sun to part shade. They do not like to dry out, especially when they are young and still getting established. However it could be that you are overwatering them and they are ‘drowning’. Deep watering on a less frequent basis is preferable to frequent light watering. I suggest that you check the soil moisture by sticking your finger a couple inches into the soil, and if it feels wet, don’t water, then check again the next day, until it feels just slightly moist, then water deeply.
Healthy soil is essential to have healthy plants. Emerald cedars prefer well-drained loamy soil. Soil types include sand, silt, clay and loam (which is a balance of all three). Very basically, you can tell what you have by taking a handful of wet soil and squeezing it, then opening your hand. If it falls apart right away, it’s sand. If it stays clumped together and then falls apart when you poke at it, it’s silt or loam. If it stays together even when you poke at it, it’s clay. If your soil is mostly clay (and much of the soil in the Toronto area is clay), you can amend it so that over time the overall health of your soil including drainage will improve. There is more information about soil and improving soil fertility here.
I also suggest that you check your trees very carefully asap for insects, spider mites specifically. Use a magnifying glass if necessary and look for webbing. Spider mites can spread to your other trees. There is more info about insects and diseases on emerald cedars in the links below. If you tree(s) have insects or disease, you should be able to return them to where you bought them since you planted them so recently.
You might need to remedy something that was done when your trees were planted. For information about everything you need to know about planting a tree correctly, click here.
The Toronto Master Gardeners get lots of questions about emerald cedars. You can browse all of our previous responses by entering ‘emerald cedars’ in the Search box under Find It Here on our website which you can find here.
Here are a few of our responses to previous questions that are similar to yours :
Newly planted emerald cedars begin withering on the top tip. Click here
Newly planted emerald cedar tree turning brown from the outside. Click here
Best of luck with your emerald cedars!