A blank for a plant protection and water saving device includes four generally trapezoidal panels arranged in a row and connected to each other at a widest part of each panel, which panels in use form four side walls of the device. Two flaps each extend from one trapezoidal panel at a narrowest part of the panel, with a cut-out being defined at a free leading edge of each flap and several spaced apart lines of weakness being provided around the cut-out. The blank is manufactured from a fluted sheet material.
