Hi, I have had 9, 6 ft Eastern white cedars now for 5 years that are in large pots on my rooftop deck. They do well with the elements being 4 seasons in Montreal Qc but turn brown on the inner tree and shed considerably each fall. They do recoupe some new foliage each summer. Is there anything I can do to prevent this thinning and keep the trees full and green. The pots are 2 feet in diameter and height. I water regularly and fertilize in the growing season. They receive full sun. Any advice would be much appreciated!
