The invention relates to a method and apparatus for injecting material into a substrate. The apparatus 10 comprises a needle assembly having a needle 14, a movable central portion 26 and a substantially stationary top portion 26. The material to be injected 17 is threaded through apparatus 10 into needle 14, and is cut to the desired length by cutter 18. When needle 14 penetrates a substrate, an additional portion of material 17 is fed into the apparatus 10, and when needle 14 is removed from substrate 12, the additional material pushes into needle 14, forcing cut portion 16 to remain in the substrate. In the method of using the apparatus, additional steps for orienting the angle of the apparatus, and steps of controlling the concentration of the injected material in the substrate may be included.