I purchased and planted 3 Emerald Cedar in the middle of April 2020 (Toronto). I used a mix of soil that was removed from the site, and nutrient dense soil. The root ball was just barely covered, leaving an inch of trunk exposed, with soil slopping away. Also added mulch to the area, although not within several inches of the trunk. It’s now the 3rd week of May and a limited number of branches have started to turn yellow. One of the cedars in particular has this dark blue/black discolouring on some of the branches. I’m only able to attached 1 photo, so I’ll share the particular discolouring I’m most concerned about. But, I’d be curious to know why some of the other branches are turning yellow, or even pale in colour.
I’ve attached pictures below to get a better opinion on what I should be doing to care for the cedars.
thanks in advance for your help!
Thank you for contacting Toronto Master Gardeners.
The black colour on your cedar could be due to a number of things (e.g. pet urine, sooty mold, exposure to fertilizer salts etc.), but is most likely black flagging, a non-disease discolouration caused by some type of environmental stress.
The stress of recent planting and environmental stresses related to soil quality, watering and/or sunlight could be responsible for the black flagging and the yellowing of some branches.
Your trees have been planted at the right height and with proper mulching. We recommend that a tree hole be back filled with existing soil. So, do not fertilize your trees again this year.
Make sure your cedars get at least 6 hours of sunlight each day.
Cedars prefer moist, organic, but well drained soil. They dislike dry, sandy soils, as well as excessively moist clay soils.
Cedars are relatively shallow rooted so they are susceptible to drought stress. Watering thoroughly and deeply when soil is dry is key for helping cedars take root. Continue to water thoroughly when dry throughout the season. Make sure the roots do not sit in water.
For further information, please check out the Toronto Master Gardener website at the links below: