Plant Medium For Living Roof

These aggregates make a good basis for a growing medium.

Plant medium for living roof.

Not only is it bulky and heavy it can have potential chemical and pathogen contaminants and if not screened may contain rocks or debris that may make the product inconsistent. For the best green roof medium the growing media should contain the following. An all purpose soil less peat free potting mix is fine for growing herbs and other edibles but mix in plenty of perlite to both improve drainage and save on weight. Now comes the growing medium which for a sedum roof should be at least 8cm 3in deep and for a roof of wildflowers herbs salad and strawberries at least 15cm 6in deep.

The targeted saturated weight of roof top growing media should be 48 65 lb ft 3 3 4 kg m 3. As well as affording excellent ground cover this hardy easy to maintain plant grows happily in a shallow layer of substrate minimising the amount of pressure it puts on a structure. Soil s saturated weight can reach 120 lb ft 3 7 5 kg m 3 which is far too high for roof gardening. Sedums are one of the star plants for creating a green roof and a sedum roof needs no extra growing medium.

Lightweight volcanic aggregate such as pumice or lava. The natural properties of sedum make this succulent plant extremely suitable for roof greening. These materials are available throughout the west coast of north america. Succulents are plants that store water in a part of the plant.