Hello - I planted 7 green giant arborvitaes in a berm four years ago. I planted them in a diagonal pattern about 6 feet apart. So there are 3 in the front row and 4 in the back row. The arborvitae's go east to west along the north side of my property. All of the arborvitaes have been growing very well, except for the one that is farthest to the east; it just stopped growing about 2 years ago. This year it developed cones on all of the branches, but has not bloomed like all of the others. Now the cones are turning brown. Does anyone have an idea why this one arborvitae would grow well for 2 years and then stop growing? I don't think it is from lack of water, or a lot of mulch too close to the stem. Please see attached pictures. The 1st pick has some orange string tied around the branch so I could keep checking the same branch. In pic # 4 you can see the 7 arborvitaes along the fence line. Thank you.