Late last spring (2015) we planted 10 approximately 3 1/2 foot Green Giant Arborvitaes. After about a month or so, they started to brown, more or less from the inside out. We suspected shock but also watered more, and by fall they mostly recovered.
This spring and summer they looked great, very little brown. All of a sudden, beginning end of September they started to brown, again more or less from the inside out. The pace of browning seems to be rapid and increasing, at least to this point. The amount of browning, 1/4 to 1/3 of the tree seems excessive for normal winter thinning, but that's just a guess. All of the trees, spaced about 5 to 6 feet apart, are exhibiting the same behavior.
Does this sound normal, or should we be taking some action? the trees are now about 41/2 feet, and we are located on Long Island, NY. Thank you.