Because of the difficult winter here in the east, my 4-plant cedar hedge is dying. It is only 4 plants wide and about 6 feet high. I have put evergreen spikes in the ground and there isa lot of new growth on the top. There is also very little new growth on the sides, where I want it to afford me privacy, but it's very slow and sparse. I trimmed the growth at the top so sun and rain would get into the entire hedge, but don't know what else to do to help this little hedge. Help!