Green Roof

A roof on a building onto which plants are grown. The roof will typically have a waterproof membrane immediately on top of the roof, followed by a shallow drainage layer, some growing media and then the relevant plants. Where the growing medium is negligible (<50mm) then low growing drought resistant plants such as Sedum species or Sempervivum species might be grown, whilst where an intermediate depth (50-150mm) of growing material is provided then this will be suitable for taller herbaceous perennials (e.g. Achillea species) and ornamental grasses (e.g. Stipa tenuissima), whilst for the inclusion of shrubs (e.g. Lavender, Heathers) this might be up to 300mm depth. An irrigation system might also be provided, but this depend on species present and local climate conditions.