Abstract: This containment structure comprises a sheet-like container defining a plurality of cells for accommodation therein of small plants, in particular for cultivations in greenhouses, and a container holder having a substantially box-like shape. The containment holder removably supports the container and has engagement members allowing easy and reliable stacking of a plurality of such structures, cross-pieces for setting the position of the container with respect to the holder and recesses in the lateral walls for aerating the small plants accommodated in the cells.