A horticultural growing and support medium is disclosed. The horticultural growing and support medium includes a synthetic foam slab permeable to water. The foam slab has a first growing surface, wherein plants grow to ambient, and an opposite second draining surface, separated from the growing surface by the thickness of the block. A limited portion only of the second draining surface is coated with a coating having a permeability to water substantially lower than the slab material, preferably substantially impervious to water, for controlling the draining and storage of water contained in the slab. The porous slab is made of a synthetic foam having an open porosity.