Proportions of components vary among substrates based on target vegetation green roof type and other considerations.
Green roof substrate composition.
Lastly skinner s article provides very helpful information on green roof substrate composition.
The vegetation properties total canopy cover plant composition species richness were recorded during the growing season.
Growing substrates for green roofs are typically composed of a mix of inorganic mineral and organic components.
Greenhouse trials presented here show that relatively minor changes to green roof substrate composition can have major effects on plant growth physiological performance and drought tolerance.
They can include scoria ash pumice sand coir pine bark porous chemically inertfoams and even recycled materials such as crushed bricks and roof tiles.
Whc indicates how well the growing substrate retains water whc should be 35 or greater for an extensive green roof and 45 for an intensive green roof up to a maximum of 65.
Ph total nitrogen n tot organic carbon c org cation exchange capacity cec electrical conductivity ec and substrate moisture.
Whc will vary inversely with afp above and an acceptable balance of the two must be achieved.
He notes that extensive green roof soils are typically between 3 and 6 organic by mass but that additional organic matter can be added initially to help to establish young plants.