As a follow-up to Dr. Brad Rowe’s research (Click here) on blue-green roofs and stormwater retention, a study was conducted this year to quantify the irrigation needs and plant growth in the RoofBlue® RETAIN™ system. We compared plots of modules-only vs. modules + RoofBlue® RETAIN™, with and without irrigation (irrigation was applied only when wilting was observed at 8 am, and only at moisture holding capacity of each module type).

RoofBlue® RETAIN™ Findings:

For plots that were irrigated, we observed that the use of RoofBlue® RETAIN™ led to:

  • Lite (50% reduction in irrigation)
  • Standard (78% reduction in irrigation)
  • Deep (43% reduction in irrigation)

Compared to the module-only plots, plant growth (biomass) was 37-123% higher in RETAIN plots of all depths for the non-sedum species. The sedum species weighed more with the RETAIN accessory for the lite and standard plots that were not irrigated (57% and 0.7% respectively), while the irrigated standard and deep plots had less biomass in the module + RETAIN plots (-12% and -25% respectively).

Deep Module + RETAIN on left Module only on right

These promising results in Western Michigan show that RoofBlue® RETAIN™ has the potential to lower irrigation requirements, while increasing plant growth in your upcoming roofing project!

For more information, check out our full white paper (here)