Rooftop Vegetation on a Building by Means of Light Weight Substrates

Abstract

We developed a simple hydroponic system for the rooftop vegetation consisting of light weight materials for planting substrates and an equipment for water supply. The cultivation experiment has been conducted from July 1987 to June 1988 on the rooftop floor of the college building of University of Osaka Prefecture. Three materials of planting substrates; rockwool, peatmoss, and perlite were used and tested whether these were adaptable for the cultivation of plants on the rooftop or not, especially the rockwool was tested in detail.
Many kinds of plants grew well on the rooftop floor by the system, in spite of the thickness of substrates were as thin as 75 to 100mm in the case of the rockwool. It is revealed that the rockwool is able to apply for the substrate of the rooftop vegetation by transplanting of younger tree or seedling.
The amount of evaporation from rockwool substrate on the rooftop occupies 40% for ground covering plants and 80% for low bush trees of total evapo-transpiration, so the mulching by any ground covering plants is effective for water consumption, good landscape, and managements of cultivation.
In this system, it is very easy to move the plants with substrates, so that we can plan rooftop gardens with many patterns of plants layout. The vegetation system would contrbute to make the good landscapes on rooftops and open spaces in the urbanized areas.