News from our Sponsor Hunter Industries: IRRIGATION on GREEN ROOFS? A Look at Green Roof Irrigation for Traditional Irrigation Professionals
IRRIGATION on GREEN ROOFS?
A Look at Green Roof Irrigation for Traditional Irrigation Professionals
By Todd Polderma, Vice President of Marketing, Hunter Industries
Green roofs have rapidly gained popularity worldwide over the past decade. Particularly in urban areas, the benefits of slowing runoff, mitigating the urban heat island effect, restoring habitat, improving natural surroundings, and the concept of biophilia all support this expansion. Whether you are in New York, New Delhi, or anywhere in between, green roof irrigation is a key component to ensure healthy, durable plant material. Even in wet and cooler climates, plant establishment and drought protection make irrigation a wise investment. So now that we have established that irrigation is an important part of any green roof project, let’s explore the differences in irrigation equipment and application compared to a traditional system that you would find on a corporate campus, sports field, or garden.
The main difference in irrigating a green roof over a traditional system is the soil. The green roof industry calls it “growing media.” This growing media is specially formulated to be as lightweight as possible while having enough organic material to support plant life. To achieve this, growing media suppliers engineer the soils to be many times more porous than sand. So the challenge for green roof irrigators is to apply water to the growing media as slowly and as uniformly as possible while preventing drainage, stopping runoff, and supporting the plant material. Typical drip irrigation has been largely abandoned because of the rapid vertical movement of water through the soil, which provides little water to plants. This leaves the green roof designer to choose one of the following irrigation methods to provide the best results for the project.
Water can be delivered overhead in the form of rotors or multi-stream, multi-trajectory (MSMT) devices such as MP Rotator® Nozzles from Hunter Industries. These products apply water much more slowly than traditional sprays and are designed to cut through the wind, which is common on rooftops. MSMT technology produces the most efficient overhead irrigation delivery option.
Because the growing media is so porous, providing irrigation below grade requires a mechanism for water to be moved horizontally. Fleece-based irrigation such as the Eco-Mat™ System from Hunter Industries does just that. It is installed just below the optimal root depth of the plant material, putting water where the plant material can use it, aiding in horizontal water movement, eliminating over-spray, and providing additional water-holding capability and availability for lightweight growing media. This
method also allows the application of nutrients directly to the roots using a fertiliser injector or fertigation system.
Control and Accessories
An irrigation controller makes up the brain of an irrigation system, while the valves simulate the heart. Both can be powered by AC or DC (battery) energy, and some can even use solar power. There is no difference in the valves or controllers used in green roofs or traditional systems. On larger projects, many irrigation professionals can
connect the green roof valves to the main irrigation system controller. Advanced features like cycle and soak, which is present in many modern controllers, can assist with maximising water absorption in the lightweight growing media. On small or isolated areas, a tap timer is a viable solution to control automatic irrigation. The BTT Tap Timer from Hunter Industries is designed for use with a hose faucet. BTT uses a mobile app with two irrigation modes and two start times each to program watering schedules, providing efficient light irrigation with simple operation.
Accessories help manage irrigation by providing the tools for maintenance and operation of the irrigation system. Weather-based, or “smart” control, is today’s buzzword for efficient irrigation practices. On-site sensors should be added to a green roof system to provide daily, weather-based irrigation adjustments while providing rain and freeze shutoff protection just as they are used for landscapes on the ground. Remote controls make system tune-ups quick and easy.
Green roofs are designed to provide many public and private benefits, and healthy plants are integral to the success of all. Regardless of the location and climate of your green roof, a well-designed, correctly installed, and properly maintained irrigation system efficiently provides the water necessary to keep plants healthy, delivering successful benefits to the environment and community for many years. With Hunter irrigation products, irrigation professionals have the best-in-class tools and equipment they need to successfully irrigate green roofs.