The Best Most Light Weight Growing Medium For Green Roofs

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.

The best most light weight growing medium for green roofs.

The extensive green roof lightweight cost effective and probably the most popular of the green roofs. Lightweight volcanic aggregate such as pumice or lava. In general the bulk of the water storage in a green roof buildup is in the growing medium. Green roof substrate has been researched developed blended and improved over several decades.

These aggregates make a good basis for a growing medium. This of course can be reflected in the cost of building materials. Because they absorb water sedums are commonly used on green roofs. 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.

To display the best plants for green roofs and to trial untested plants for their. Furthermore they are drought and wind tolerant. The extension includes high quality waterproofing a root repellent system a drainage system filter cloth and a lightweight growing medium and plants. However the factors allowing for a lightweight roof can create a high stress environment for plant material.

Cally described by the depth of the growing medium extensive semi intensive and intensive. Over a 100m2 green roof with 10cm depth of growing medium the weight saved by using substrate instead of soil is considerable. 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. Furthermore it should be made up of a blend of materials that is not too heavy for a roof to support.

These materials are available throughout the west coast of north america. 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. For the best green roof medium the growing media should contain the following. 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.