Given how narrow your garedn is I woudl not haev a hedge - why not a fence
with trellis on the top and stuff growing up it? You could grow veg up part
of it (beans. peas) or grow evergreen clinbers if you want somethign there
all year. In general hedges do taek up nutrients, you woudl have to cutt hem
and it is not easy to get one less that 18'' thick if you also want it high
enough to screen next door. It woudl also end up dominating the garden some
what.

--
Hayley
(gardening on well drained, alkaline clay in Somerset)