Abstract: A liner (11, 20, 27, 30) for a plant container is formed by firstly compressing sphagnum moss into a thin but reconstitutable sheet. The sheet may be then assembled into a three dimensional liner for insertion into the plant container and secured in that configuration. The formed three dimensional liner has one or more walls (2, 13, 21, 36, 38) extending in an upstanding configuration to generally conform to the shape of the plant container. The wall(s) are self-supporting in the upstanding configuration. In a preferred embodiment, an outer surface of at least a portion of the liner (11, 20, 27, 30) may be partially reconstituted.