The Best Most Light Weight Growing Medium For Green Roofs

To display the best plants for green roofs and to trial untested plants for their.

The best most light weight growing medium for green roofs.

Furthermore they are drought and wind tolerant. For the best green roof medium the growing media should contain the following. Green roof substrate has been researched developed blended and improved over several decades. 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.

This of course can be reflected in the cost of building materials. Cally described by the depth of the growing medium extensive semi intensive and intensive. Extensive green roofs have a growing depth of 3 to 6 inches and are typ ically lighter in weight with a saturated weight of 15 to 30 pounds per square foot. Depending on the plants grown most will perform best in a blend of a peat based growing medium with lightweight clay aggregates coir chunk or heavier material to help support the plant throughout one or more gardening seasons.

These aggregates make a good basis for a growing medium. Pumice is somewhat porous and is lighter than most aggregates. Because they absorb water sedums are commonly used on green roofs. However the factors allowing for a lightweight roof can create a high stress environment for plant material.

Over a 100m2 green roof with 10cm depth of growing medium the weight saved by using substrate instead of soil is considerable. Lightweight volcanic aggregate such as pumice or lava. The extension includes high quality waterproofing a root repellent system a drainage system filter cloth and a lightweight growing medium and plants. These materials are available throughout the west coast of north america.

When installed the sedum blanket including the 20mm of growing medium is rolled out onto either 50mm 70mm of growing medium standard method or directly onto a moisture retention blanket ultra light weight method. A green roof is defined by the green roofs for healthy cities grhc organization as a system that s an extension of the existing roof. 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 more information about growing media please feel free to contact your premier tech grower services representative.