Question
I have a two hundered foot cedar hedge,  three trees deep,  spaced about three feet apart.   The hedge is 10 to 16 feet high.  When planted,  the trees were 2 to 3 feet tall.  My question.  The hedge is gradually loosing it's thickness.  It has been giving me good privacy up until the last couple of years,  but now it is getting thin and I can see the neighbours houses again.   Do I need fertilizer,  and if so how much and what kind.  Or is this something natural that happens to cedar trees,  and they will thicken up again in time?

Answer
These are trees and as such as they grow taller the lower branches will be shed. To keep them as a hedge the top will need to be cut tot the height you desire. This will be an annual thing. I would fertilize with hollytone evergreen fertilizer(espoma brand). Fertilize in the spring and again in the Fall.  Starting 6 inches away from the base of the plant, scatter the fertilizer evenly all the way out to the "drip line" -- the outside perimeter where water might drip down from the plant's leaves. I would use about 1 lb per inch of trunk diameter. Check with your local nursery for this fertilizer.