The method of stimulating a plant substance is disclosed. The method has the steps of activating a pressure pulse or an acoustic shock wave generator or source to emit pressure pulse or acoustic shock waves; and subjecting the plant substance to the pressure pulse or acoustic shock waves stimulating said plant substance wherein the substance is positioned within a path of the emitted shock waves. In one embodiment the emitted pressure pulse or shock waves are divergent or near planar. In another embodiment the emitted shock waves are convergent having a geometric focal volume of point at a distance of at least X from the source, the method further comprising positioning the substance at a distance less than the distance X from the source. The substance is a plant tissue having cells. The tissue can be a seed, zygotic embryo or somatic embryogenic culture of somatic embryos of plants. The plant may be a vegetable, tree, shrub or tuber. The tissue may be a part of the root system, a part of the stem system or a part of the leaf system. The method of stimulating includes activating the cells within the treated tissue thereby releasing growth factor proteins or other chemical compositions promoting growth and accelerating germination or plant growth.