how deep should you subsoil
The lower layers of soil, which make up the subsoil, are composed of materials that block the growth of roots, such as sand, gravel, rock, heavy clay, or cement-like substances. The depth of topsoil is rated from very shallow, which is less than 10 inches deep, to very deep, which is more than 60 inches deep. Plants grow best in topsoil rated deep, which is 36 inches, to very deep. They develop strong root systems that provide better stability and support, which is especially important for large shrubs and trees.