A planting tray (10) for greening roofs, includes a tray or reservoir (14) for retaining water, a mesh root guard (48) in the form of a plate which is supported above the base of the reservoir on a ledge and on walls. The mesh root guard (48) is a perforated planar plastic plate. The root guard defines an array of cruciform holes (50) as well as a number of elongate slits (52). There are one or more rows of parallel slits (52) spaced across the plate. The slits define a number of opposed teeth. A long continuous strip of geotextile (46) is placed along each row of slits and a loop (47) of geotextile is pushed down into each slit in turn using a suitable tool. The teeth flex and grip the wicks (47) and depend into the reservoir for wicking water from the reservoir. One or more outlets/exits may be defined at a height above the base which is approximately at or slightly lower than the height of the ledge above the base.
