Landscape Architecture Program


Media Modifications for Native Plant Asemblages on Extensive Green Roofs

Richard K. Sutton, UN-Lincoln

Document Type Article

This was presented at the GRHC in Baltimore in June 2008.


Great Plains and Midwestern regions might profit from selecting species representing nearby mid and short grass prairies, not the tall grass prairie. Such assemblages should exhibit needed characteristics desirable on low-input extensive green roofs to withstand stresses of: drought, heat, cold, nutrient deficiencies and wind before providing expected benefits. While published research, and its recommendations are inconclusive or negative regarding efficacy of native prairie species for extensive green roofs, establishment data gathered in this study demonstrates placing native plant assemblages for extensive green roofs into modified media significantly improves their establishment and growth.

In the short-term soil doughtiness limits plant establishment on green roofs; in the long-term availability of micro-nutrients may limit plant growth and survival. This integrated study examined the use of a hydro-absorbent polymer gel (Horta-Sorb™) and native prairie soil microbes in the initiation of an extensive green roof planted with native grasses, sedges and forbs. After one growing season results showed enhanced plant vigor from hydro-absorbent polymer gel application and its interaction with mycorrhizae inoculation. Results on specific species performance will be reported elsewhere.