Device enabling plants or a floral composition to be supported, especially on a post, outside and in all seasons. It is composed of a cast-alloy support 1 surrounding a spherical container 3 in the form of two half-parts 3a and 3c which can be used, depending on the seasons, together or separately, the lower half-part 3a acting as a basin in hot periods, the assembly of the half-parts joined together acting as a greenhouse in cold periods. <IMAGE>