CLEVELAND - Most lawns don’t emulate a soccer field. The land can swoop and swell with slopes, and plant beds can divide it into sharp-cornered sections. Under these conditions, technicians can run into water requirement discrepancies, noted Rick Pate, president, Pate Landscape, Montgomery, Ala.
"In the same plant bed you can have such dramatically different water requirements," he said. "Annual beds need more watering frequency - almost daily watering - whereas you can water your shrubs less."
Also, as plants grow and change, their water needs fluctuate or diminish, he pointed out. "Plant beds are a dynamic situation," he related. "Three years from now, they could need more adjustments because the plants are changing. Plus, people want to move plants around. You don’t see people changing their turf areas, but people might plant different varieties in the bed every year, so you get a different situation."
These variegated water needs demand special zoning that separates plant species and creates different zones for full-circle and part-circle sprayheads, suggested John Ossa, business development, Jensen Landscape Services, Cupertino, Calif. "Hydrozones, defined as a plant grouping that has differing water requirements, are irrigated separately," he explained, adding that environmental conditions, such as sun exposure, also determine these parameters. "Ideally, you would like to separate the different conditions so you can distribute the appropriate amount of water."
Some technicians turn to drip irrigation to manage these high-maintenance situations, Ossa said. This sub-surface option is ideal in drought-ridden areas and does not produce overspray, conserves water and ensures proper dispersion. However, the method comes with constraints; it doesn’t offer turf coverage and can be difficult to monitor.
Besides beds, technicians tackle land grade issues, which also can affect zoning. Dramatic slopes cause water run-off, which could leave a hill with a dried-out top and an over-saturated bottom, said Scott Fay, president, Treasure Coast Irrigation, Hobe Sound, Fla. "If you have an aggressive slope and are getting run-off, you want to run the spray times much shorter but water more frequently," he suggested. "If you run the system too long, it will just run the water off the slope." Ideally, technicians should arrange elevated areas that require more frequent watering on different zones than their less-demanding low points.
Pairing zones entails a little calculation, Pate said, noting that volume and pressure are water’s two major variables. "If you have 10 feet of elevation change, you could have as much as 5 pounds of pressure difference, so that could make a difference in your system’s performance," he explained. "You need to consider in your calculations that the higher elevation has a lower pressure because you lose pressure as you put water up the hill."
While adjusting the system to accommodate to land characteristics, technicians also should take into account the height of the spray stream, Pate added. "Sometimes you need the water to throw under things and sometimes you need it to throw over," he said, listing barriers like shrubs and trees. Sprayhead streams that hit certain tree species can damage the bark and disturb the tree. "If the trunk of a tree is wide, we’ll plan the system to throw water past it," he said.
The author is Associate Editor of Lawn & Landscape magazine.