I had 2 rows (~200 trees) of 6-7′ Eastern White Cedars planted in my yard ~3 weeks ago. I’m somewhat concerned about the browning that is occurring on the trees. Is this simply transplant shock, or is it possible that they are overwatered? I checked the moisture with a meter and they have been ‘wet’ ~6″ deep for over a week now without watering (I use a soaker hose). One row is at the end of my septic leach field where the grass is always green and the soil is always moist. The other row is between my yard and my neighbours yard in the ‘trench’ area where the water runoff goes. Again this area also has the greenest grass.
Thank you for contacting Toronto Master Gardeners.
Although cedars are suited to wet soil, too much water can also be a problem. Please see below for some possible things to consider.
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.
Another potential cause of foliage browning in cedars could be due to root rot especially in clay soils where the drainage is slow. Over watering can kill roots, so use sprinklers at short intervals during the day to keep soil constantly damp. Root rot or root damage due to poor drainage could also support the pathogen Armillaria fungus (also known as honey fungus). Symptoms to look for are the sudden death of the upper parts indicating the failure of the root system’s ability to absorb water.