Know before you grow

Before any construction begins, an extensive site analysis is the key to success on a landscape or golf course. After considering the basic layout like slopes, parks and streetscapes, it’s time to work with the landscape architect on the plant palette.

“We identify with them the type of plant palette and how they intend to zone or group the plants, so by the time we begin the irrigation design, the site is well-zoned with respect to plant water requirements,” says Steve Hohl, principal at Water Concern and past president of the American Society of Irrigation Consultants.

If the plants haven’t been determined, Hohl and his team will try to zone out areas that can be planted with varieties that have similar water requirements. “[The landscape architect] will come in and say ‘This is what we want to use and if you look at their palette, it’s a complete mix,” he says, naming drought-tolerant plants mixed with moderate use plants and different types of turf. “So the water use requirement of each of their species is all over the board. So what we try to do is get them to look at the plant palette on a global sense.”

Water Concern will then determine an irrigation plan, using big bubbles on a master plan to show areas with low to high water needs.

Reviewing the rainfall.

When Hohl and his team are making their plans, they don’t assume any rainfall, giving them a worst-case scenario to start with. “A good example of that is that in California this year. We had very, very little rain. Our water use estimations better prepare our clients for these abnormal conditions with respect to water needs and budgeting,” he says.

Watching the sun and shade.

Taking into consideration any buildings that might cast shadows on a project area, Water Concern will carefully plot sun and shade zones. Trees are a big factor as well, needing recurring observation as they grow and cast larger shadows.

“Many times a planting zone with small trees starts off with a full sun microclimate, only to evolve into full shade within a few years. In our water management work, we promote frequent observation of how trees afffect microclimates so irrigation management can be adjusted,” Hohl says.

Testing the soil.

In areas with soil variations, an analysis is done and the areas are zoned on the master plan so that the water application can be adjusted, Hohl says.

According to Stephen Smith of Regenesis Management and past president of the ASIC, amended soils are one of the biggest issues in landscapes. “It’s so common that the top soil gets removed and stock piled and unfortunately it has happened where the stock pile gets sold. So the top soil never sees the project again and then you have construction equipment driving around on what used to be subsoil,” he says.

Since the soil is often brought back into good condition with organics and fertilizers, it’s hard to know what the real condition of the soil is, he adds. “If you haven’t been involved in the spec-ing and the soil amendments and soil prep before irrigation is brought in, then you’re really making a guess at what the soil condition is.”