Dying Emerald Cedars

(Question)

We live in Markham, Ontario and planted 4 emerald cedars (4-5 ft high) closer to the outside wall of our house . These were planted in mid-May of this year and were green and looking good till mid-June. For the last 2-3 weeks the leaves have been turning brown and are almost crisp and dry to touch now. After doing the scratch test, the tree trunk appears to be slightly green-and-white, not dry from the inside. While planting, a mix of top soil and triple blend (purchased from Walmart) had been used. The trees have been regularly watered (once every 1-2 days but not heavily) since their planting. Are the trees already dead and could this be due to the intense hot and dry weather we are facing this summer? Or is there another underlying cause? Is there anything that can be done to save these trees? It is frustrating that these newly planted trees grew well for the first 5-6 weeks before they started browning. Any help will be much appreciated.

(Answer)

Thank you for contacting the Toronto Master Gardeners with your inquiry.

You mention that you have watered your trees once every 1-2 days bit not heavily. With this years extreme heat and the lack of rain water  I suspect that the problem with your trees are that the roots are not receiving sufficient water.

Cedars naturally grow in wet ground.  Regular watering is a must, especially in drought conditions.  Water deeply and thoroughly once or twice a week as opposed to watering more often and lightly. When you water, have the water run slowly, a soaker hose works well for a long period of time. If you run the water for at least an hour the water will be able to soak down into the roots. Let the soil dry out before you re-water. You may find you are watering less often but the trees will do better. Small amounts of water will not make it down to the roots. With evaporation, run off and grass etc. competing for the water very little if any will make it to the roots.

Mulching is important to hold that water in the root zone, deter weeds and shade the roots. Make sure none of the mulch it touching the trunk, leave a small empty ring right next to the trunk so air can get to the flare

Were the trees planted too deeply? Take a look at the trunk of the tree. Every tree has a flare near the bottom where the trunk widens right before the roots begin. It is very important that the entire  flare of the trunk is above the level of the soil. If it is below the level of the soil it will break down the bark and eventually kill the tree. if the tree is too deep you will need to dig around the tree and raise it up.

Another issue you have may be the addition of triple mix with the planting. It is recommended that one uses the soil that was removed from the hole to back fill. The reason for this is with high nutrient soil around the root ball the tree is less likely to send out it roots looking for nutrients and water. It can lead to a smaller, less stable root structure. Hopefully the surrounding soil has enough nutrients to encourage outward growth.

Fertilizing the cedars with 30-10-10 three times in the growing season (May, June and July) is appropriate. Don’t fertilize in late summer, as the cedars needs to prepare to go dormant for the winter.  When fertilizing first slowly soak the soil around your cedars’ roots with water, before applying the fertilized solution, to make the soil absorbent. Then, prepare a bucket full of 30-10-10 nitrogen-rich solutions exactly as directed, and apply. Lastly, be sure to water thoroughly with an equal amount, after applying the fertilizer, but slowly, and gently, so as not to wash the nutrients away.

Another option that does not require mixing, topdressing with sheep manure compost or regular compost will not only feed the cedars but will also improve soil structure, encourage beneficial macro & micro organisms and, the earthworms will love you forever.

In late fall you can fertilize with slow release nitrogen and phosphorus, which will lend the cedars a boost come spring.

If you purchased the cedars at a reputable nursery they will be a guarantee and you will be able to exchange them for new trees. If you decide to replace them remember that the middle of the summer is a very difficult time for a tree to establish itself. With the heat and low rain fall any stresses on the tree can be amplified. It is often easier to plant in the early fall or early spring.

Good Luck!