The present invention describes polyvinylformal based plant growth medium and method of preparing thereof. The polyvinylformal based plant growth medium is used separately or mixed with known plant growth substrates (mediums). The polyvinylformal based plant growth medium is a hydrophilic porous granular material, wherein the size of pores is between 5 - 500 μm, an average size of pores is 100 μm. For mixing, the plant growth medium is granular or in the form of powder. For mixing a homogenous plant growth substrate, it may be as loose granules, extruded granules as volumetric material or as synthesized end product (minimally mechanically processed form).
