Yes, a 500%! improvement as shown in Figure 3. and here is how I proved it.
On the 25th of July I planted 16 pots with Radish plants in my glasshouse in Sydney, Australia. 8 black pots were planted with a standard green roof growing media. 8 green pots had a 20mm layer of Knauf Green Roll in the bottom of the pot and 10% Knauf cubes mixed into the same growing media. Once plants were mature on 17th of August they were placed in a dry zone, a shaded window sill in my office where they received no further watering.
Plants in Knauf growing media lasted 21 days with no water. Five or 62.5% of Knauf plants lasted this period. Only one plant or 12.5% of plants with no Knauf lasted 19 days. Figure 1 shows a comparison of plants.
What Sydney Environmental Soil Laboratory (SESL) concludes after a 12 month trial that: “The Flocks (Urbanscape Flocks) product provides soil structure with significant reduced slumping over time in comparison to the lightweight media without Flocks (the Control). The Flocks also allows maintained air-filled porosity without significant reduction in oxygen levels. The addition of Flocks at a rate of 20- 30% to the lightweight media blend initially improves the water holding properties of the mineral based blend by around 9%. The water-holding capacity improves with time (5% improvement) as the media settles however not at the expense of the air-filled porosity. The Control showed higher WHC but this was at the expense of the AFP. The toxicity bioassay shows germination to be at an acceptable rate with the 30% contribution of Flocks however the growth rate isn’t as rapid as the 100% lightweight media. SESL recommends a full growth trial is undertaken to measure the effects of drought on non-irrigated blends.”
What does it mean for your green roof?
There will be substantially less watering required for plants growing with Knauf Urbanscape. Plant growth will be substantially better on your green roof. Stormwater runoff from your infrastructure will be greatly reduced. Knauf can be easily installed and saves a lot of money in material handling and water. It’s light weight, means that even more money is saved in structural requirements of your building, retrofitting older buildings now also becomes possible.
Below are photos of my plants on the shown dates.
Robert Griffith BEnvSc, Hort. +61 468 787 071