A plant cultivation solid medium for potting a plant includes a water retention block body (2). The water retention block body (2) has a top surface (23), a plant-receiving chamber (213) that is indented from the top surface (23) and formed with a top opening in the top surface (23), a bottom surface (24) opposite to the top surface (23), and an air chamber (221) indented from the bottom surface (24) and formed with a bottom opening (223) in the bottom surface (24). The bottom opening (223) has a cross-sectional dimension greater than that of the top opening (214).
