A modular unit, system and method include a base layer having a plurality of reservoirs configured to prevent water flow through a lower portion, the lower portion for contacting a support surface, and having interlocking portions configured to interlock adjacent base layers when installed. A water permeable layer is disposed over the base layer. A detachable wall is mountable on the base layer to contain planting media. The water permeable layer may include a water-holding capillary fabric mat layer with entangled filaments.
