From this site: http://www.stephen.a.morton.btinternet.co.uk/twws/rankandfile.htm
Blocks of rubberized horsehair can be purchased from upholstery suppliers; these can be cut into strips using a scalpel or very sharp scissors, to form rough irregular hedges. In order to complete your hedge, either use paint or cover the "hedge" with spray a d hesive or dilute PVA before covering with flock or scenic scatter. Shake off the excess and allow to dry. If necessary, repeat to form a thicker covering before sticking to your chosen base material. If you cannot find horsehair blocks, try using block s of low-density foam rubber, (car wash sponges) the lower the density, the larger will be the holes and therefore the hedge will look rougher and more natural.