Seeding Green Roofs with Native Grasses

During six years of native grass establishment and growth on four green roofs, we sought to understand appropriate seeding seasons and spacing, the amount of time to reach the industry 80% coverage threshold (FLL 2008), the seed yield projections for volunteer plant infill. We also produced and tested methods for successfully and inexpensively seeding and determined “as needed” irrigation protocols. The suite of techniques examined improves and enhances the use, establishment, and management of native grasses on green roofs and reduces green roof costs. 

Plant Species Survival on Three Water Conserving Green Roofs in a Hot Humid Subtropical Climate

The quantification of ecological services from green roofs in Texas is emergent and proving advantageous. Identification of candidate plant species for green roofs in Texas and similar hot and humid subtropical climates is limited. Three extensive green roof systems and research sites in Texas employed different water conserving techniques ranging from no irrigation, to sparse application during dry and drought periods, to frequent watering with harvested rainwater. Thirty-four candidate species were identified for hot and humid climates from among the three sites. These findings help to establish a reference point for future investigations of green roof plant survivability.

Rethinking Extensive Green roofs to Lessen Emphasis on Above-Ground Biomass

In the future, most green roof applications will not be highly visible, yet these roofs will still provide the benefits of heat island reduction, stormwater control and biodiversity for hard-surfaced cities. However, human bias in wanting more biomass and visible blooms leads green roof horticulturalists and their approach of maximizing those aspects down a slippery slope that, in turn, leads to increased hours of labor, over-watering and fertilizing and specifying too many cultivars.

Fertility Management for Tomato Production on an Extensive Green Roof

Green roofs offer an alternative growing space to provide fresh vegetable products to urban
markets. The soil component is an important aspect of efficient green roof production systems
and adequate fertility levels are often lacking in media that are required to maximize plant
growth. This research project evaluated four fertilizer treatments on „Bush Champion II‟ tomato
(Solanum lycopersicum) growth and yield in a 7.62 cm green roof production system: (1)
vermicompost tea, 2) Miracle-Gro fertilizer, 3) Organic Miracle-Gro fertilizer, and 4) no
fertilizer. Treatments were applied weekly and ripe tomato fruit was harvested from June to
August. Results indicated that Miracle-Gro® provided the highest total tomato fruit yield, which
was 30% and 50% more in 2011 and 2012, respectively, compared to the next highest treatment -
Organic Miracle-Gro®. Plant vigor, chlorophyll content, and tomato yields indicated that
tomatoes can be successfully grown in a 7.62 cm green roof medium when given adequate
fertilizer applications.