A single-piece tray for hydroponic cultivation, composed of a plastic material shaped to define identical cultivation cells inside the tray. Each cultivation cell has: a housing defining a raised plane and configured to house a bulb or seedling to be cultivated, with a hole dimensioned to support the bulb or seedling without letting it fall through, while allowing its roots to protrude below the tray； a buoyant portion, defining a lowered plane intended to sink below a waterline, and delimited by side walls, each buoyant portion defining: a bottomside with a first height, a waterline zone with a second height, a topside with a third height； the sum of the first, second and third heights corresponding to the height of the side walls which connect the raised plane to the lowered plane. The side walls forming a channel.
