I planted a row of about 30 4' Techny Arborvitae's as a privacy screen about 3 years ago. About 1/2 of them look absolutely beautiful and have grown to about 7'. The other half are extremely sparce, have died off in some areas, and are only about 5' tall. I had to replace 1 of them last year because it was almost totally dead. What is strange is that the 15 "good" ones are all consecutive, on slightly higher, dryer ground. The other 15 are consecutive,on slightly lower, wetter ground. I thought that may have something to do with it. But the one I replaced last year looks great this year, and is in the wetter area. So I guess there goes that theory. I'm just not sure what is going on with these trees. They seem to get buds every year, and then most of the buds die off and turn brown. The others bud, and seem to keep growing. My only other thought was that I did overwater the poorly growing trees the first year they were put in. I left the soaker hose on for 3 days by mistake. But that was 3 years ago. I wish they would either just die or get on with growing. The disparity between the 2 sections of trees is becoming quite noticeable. Doe anybody have any idea what might be going on? Should I dig up the 15 bad trees and plant new ones (expensive!) while the height disparity is not that great? Do I just wait it out and hope they recover? Do I fertilize them somehow to try and jumpstart them? Any help or ideas would be greatly appreciated.

Thanks,

Dave