Emerald Cedar turning brown

(Question)

I planted 10 five foot emerald cedars this year in April. I water them everyday. I don’t know what type of soil I have but all my neighbours have nicely grown cedars and other trees.

One of my cedars started to turn brown with hard leaves. I fertilized that one after it started turning brown.  Attached is a picture. It gets sunlight all the time since there no shading and my backyard backs into a farm land.  It’s planted in Wellesley, Ontario.

(Answer)

Thank you for your question from Wellesley for the Toronto Master Gardeners.

Unfortunately, your photo did not come through but we have had many people send in a similar question, so I am using a section from another answer to help you.

Below is some general information on the subject of yellowing and browning of cedars.  It provides some guidance on watering, pruning and soil amendments that you may find helpful:

• Cedars thrive on moisture and nutrient-rich soil.  Moisture deficiency after they are planted and before the ground is frozen can lead to browning of the bottom of trees.  If watering isn’t sufficient to encourage strong root growth in the last season or the roots in the root ball were not separated (teased out) before planting, roots may not be able to penetrate into the surrounding soil.  Watering deeply and thoroughly (at least once or twice a week after planting) is key so that the roots can take hold and spread.  This can be done easily by using a soaker hose along the base of the cedars for several hours.  Watering should continue well into the autumn until the ground is frozen to maintain adequate moisture through the winter.  The cold winter winds can desiccate the foliage – once the ground is frozen, the tree cannot take up moisture to replace what is lost from the needles/leaves.

• What type of soil do you have?  Soil type is very important.  If you have clay soil, roots may have difficulty growing into it, so adding organic matter may be helpful in adjusting the soil structure.  You may also want to check the root ball – if it is still intact or if you find the roots are girdled (growing around each other), you may need to find a way to tease the roots apart to encourage outward growth of new roots.  Make sure the soil around the root ball will allow the roots to penetrate into it so try not to excessively compact the soil during planting.

• Good quality topsoil and mulch should be used when cedars are planted.  Compost, triple mix or manure are good choices to add along with topsoil when planting – not only do they contain more organic material, they provide more usable nutrients for the roots.  They can easily be added as topdressing on a annual basis to help improve soil structure and allow the soil to retain moisture.  The use of mulch is an excellent way to maintain moisture around the shallow root system of cedars – it also gradually adds nutrients to the soil as it decomposes and will also be beneficial in keeping weeds at bay.

• Fertilizing the trees after they were planted is a good idea.   Although excess fertilizer can cause root burn and prevent the roots from growing, so it is vital to follow the instructions on the container carefully.  It is also important to use a fertilizer with a higher middle (P – Phosphorus) number such as 5-15-5 in order to encourage root growth.