The light choice for rooftop gardens 


The current trend of designing buildings with rooftop gardens has turned the spotlight onto the use of exfoliated, volcanic perlite as the ultimate lightweight growing medium for the application.

Planters used in pedestrian malls, rooftop gardens, over underground garages, on patios, decks, terraces and in penthouse gardens have one common problem. Weight!

Structural design on the floor, deck, or rooftop is often the limiting factor when it comes to planter weight. This, in turn, limits the depth of the planter which restricts the volume of growing mix that can be used and ultimately the size of shrubs or trees that can be planted. Conventional, fully watered soil weighs as much as 1900-2200 kg/cubic meter without the weight of plants or trees. When this is multiplied by the number of containers used, the additional weight on the structure can be enormous. Fully watered perlite and peat moss/compost growing mixes weigh about 550-600 kg/cubic meter and high quality 100% horticultural grade perlite alone as little as 80-100kg/cubic metre. This tremendous weight saving using perlite and peat moss mixes can provide architects, designers and nurserymen with a host of additional options including more extensive plantings, larger shrubs and trees and reduced design loadings for rooftops.

The advantages of using 100% perlite or perlite/peat moss growing mixes are not limited to weight savings only. Horticultural perlite is an inorganic mineral of volcanic origin and it therefore does not rot or deteriorate over time. Perlite will also retain three to four times its weight in water and water-soluble nutrients without becoming soggy, producing healthier plants and trees while requiring far less attention and less water. One of perlite’s most important benefits is that it provides aeration to the growing mix which is essential for optimum plant development. It also offers the advantages of being pH neutral, non-toxic and sterile, having been exfoliated at nearly 1300 deg C.

Its lightweight properties allow for easier relocation of containers, ensuring that they last longer because they are not subject to the stresses and strains with heavy loadings.

CemteQ develops and manufactures sustainable perlite and cement-based building materials for their significant thermal insulation, lightweight, acoustic and fire-resistant properties. CemteQ’s sister company, Sun Silicates, is renowned for producing the highest quality horticultural-grade perlite which is used by professional growers across South Africa.

Perlite is the ultimate lightweight growing medium for rooftop gardens.