These materials are available throughout the west coast of north america.
Plant medium for living roof.
Lightweight volcanic aggregate such as pumice or lava.
Carex nigra is technically considered a sedge and is often used on living roofs because its roots require less soil than most other grasses or grass like plants.
The targeted saturated weight of roof top growing media should be 48 65 lb ft 3 3 4 kg m 3.
The natural properties of sedum make this succulent plant extremely suitable for roof greening.
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.
For the best green roof medium the growing media should contain the following.
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.
Succulents are plants that store water in a part of the plant.
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.
Sedums are one of the star plants for creating a green roof and a sedum roof needs no extra growing medium.
These aggregates make a good basis for a growing medium.
Soil s saturated weight can reach 120 lb ft 3 7 5 kg m 3 which is far too high for roof gardening.