Green-Roof Maintenance: Irrigation, Weeding, Fertilizing
Some managers might hesitate to specify a vegetative system because they do not understand the maintenance requirements.
“The different vegetative roofing system manufacturers have different maintenance recommendations, so it depends on the system you’re installing,” Baumann says. “It depends on intensive versus extensive. It depends on built in place versus modular.”
Most green roofs require a core set of maintenance tasks, including irrigation, weeding, fertilizing, replanting, and replacing eroded media. These maintenance requirements, particularly irrigation, are critical in the early stages of the plant’s growth.
“Irrigation is very important,” Baumann says. “A vegetative roof must be watered initially after installation, but then it varies. Irrigation needs vary by climate. Some vegetative roofs do not require irrigation in the long term. Some only need intermittent irrigation for the first few years. Other climates demand ongoing irrigation.”
The next step in outlining a maintenance plan for vegetative roofs is determining the person responsible for maintaining the system. It might be the grounds manager. It might be someone from the maintenance and engineering department. Or it could be someone the organization contracts, due to a lack of horticultural knowledge in-house.
“With the higher intensive systems, it’s usually the grounds crew that comes in and maintains it, whether it’s cutting grass or trimming shrubs,” Bauer says. “It’s treated just as though it’s sitting out in front of the dormitory instead of up on top of the dormitory.”