Answer: BAsed on your description I am unable to tell you specifically what is wrong with your arborvitaes. This plant needs full sun and average to moist soil and is usually quite trouble free. During the establishment phase it would need an evenly moist soil to assist it in becoming well rooted. Browning and death can be related to poor planting practices (for example failure to cut encircling roots or planting too high or too deeply) or over or underwatering, or overfertilizing (this causes root damage) or possibly to a pest or disease problem. Since these are relatively new I would strongly suggest you work with your retailer (especially if there is a warranty from your retailer) and/or county extension to troubleshoot and see what has happened. I'm sorry you are having trouble with them.
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