Protection device (1) for outdoor ornamental plants, or other material, comprising a protection element (4), suitable for protecting said ornamental plants, or said other material, from atmospheric agents and from direct sunlight, bearing elements (5) for supporting said protection element (4) and fixing elements (6) for fixing said bearing elements to a supporting element; each supporting element (5) comprises a first component (8) a first end (12) of which is removably couplable with a respective fixing element (6) and at least a second component (11) that is fixable to a second end (13) of said first component (8), said second component (11) forming a lengthening of the first component (8).
