Thuja green giant

Asked June 26, 2020, 5:48 PM EDT

I just planted 2 green giants (5 gallons) 3 weeks ago. I used planting soil to backfill 2/3 of the hole. I placed 3 inches of pine bark mulch all around except for 2 inches around trunk. My trees are starting to brown and die at the top of the trees. I have sandy soil that stays somewhat wet. I'm afraid its root rot. Today I pulled the pine bark mulch away from trunk and is now a 12inch diameter of just soil. Any help would be appreciated!

Oakland County Michigan

1 Response

Hard to answer from this vantage point. Thuja GG is a tree with few problems that is tolerant of poor soils. A soil test prior to planting would have shown exactly what the soil needed, if anything, for optimum growth. Sandy soils do not stay wet. Trees are a long term investment and the process should always begin with a soil test to determine soil type, pH, nutrient levels and other important information. Transplant shock is always an issue. Plus you've planted at the worst time of the year, into the summer heat. By planting soil you may mean potting soil, sterile with few if any nutrients. Best advice when planting a tree is to use as much existing soil as possible because roots may not want to come out of cushy soil around the root zone. Check for soil moisture deeper around the trunk because this is most likely the problem. GG has a lot of surfaces for moisture loss in hot, dry, windy conditions. It's also possible the root ball could be dry while the surrounding soil is moist. After three weeks there is no root growth and won't be until the tree acclimates, which could take a year or longer. For now I would just make sure the tree stays hydrated and the situation should improve.

Good luck!