Precision performance

By Carol Brzozowski

Use drip irrigation for direct application of water for clients.

Any maintenance professional called out to do a repair would not go out on the job with just a hammer. Each project requires the right tools used in the right applications to be a success.

Similarly, drip irrigation is another tool to remember in the irrigation professional’s kit. In the right situations, it can provide low-pressure, precise results in a landscape design, delivering water directly to a plant’s root zone.

According to the Environmental Protection Agency WaterSense program, drip irrigation systems use 20%-50% less water than conventional sprinkler systems. Still, it can be a hard sell with clients.

Judith Benson, president of ClearWater PSI near Orlando, Florida, points out that drip and micro irrigation carry stigmas: they don’t work, they don’t last and they require extensive maintenance. While some municipalities require drip irrigation for new irrigation systems, most do not.

“If they have more finite water resources, they’re going to be extremely conservative with it,” she says.

One driving force for the use of drip irrigation in Florida is the Florida Water Star program. In partnership with the Florida Nursery, Growers and Landscape Association, it provides professional accreditation for landscape and irrigation professionals toward the goal of achieving sustainable project design and implementation.

Benson notes commercial landscapes in her area utilize drip irrigation more. There are low-watervolume choices among conventional sprinklers, and those are more along the lines of what customers are used to seeing, she says. The residential sector doesn’t embrace drip as easily.

“Home builders who have a very strong voice in the state of Florida, which carry a lot of weight with the municipalities, want something that’s going to look good and really works,” she says. “In Florida, the way to keep plants looking good and working well typically is the more standard irrigation because it gets the bigger curb appeal. It’s the aesthetic of the plant that helps drive or not drive micro and inline drip in the industry.”

Benson considers the stigmas with drip irrigation to be misnomers.

“I help clients cultivate azaleas, which are thirsty plants for Florida especially with micro and inline drip, and that can be done if it’s installed well,” she says.

In speaking with her clients about the benefits of drip irrigation, Benson says she emphasizes the ability to use water on demand “any day, any time of day.

Whereas with turf and other areas, any aerial-type irrigation is limited to a maximum of two days a week unless we start a variance due to a smart controller.”

Hands-on gardening buffs are good drip irrigation system candidates, Benson says, adding “they’re able to care for their landscape plants to the manner they would like.”

Benson also emphasizes some benefits of drip irrigation for a plant’s health.

“We get a lot of water damage on the plants itself due to aerial watering in Florida,” says Benson, adding plants can get “sunburn” if not properly hydrated in a manner drip and micro irrigation provides.

The bottom line: drip irrigation can work well in some applications with certain caveats.

“Drip irrigation needs to be designed, installed, maintained and operated properly,” says J. Randall Merriott, owner of Irrigation Dynamics in Lubbock, Texas. “If you do those four things, you’ll have success.”

Landscape professionals offer several tips to attaining that success.

Design for precision

A drip irrigation system can be used in new installations and retrofits or by adding to existing systems. Where water supply pressure is typically greater, emission devices should include pressure compensation to ensure a consistent flow rate.

Drip irrigation is most practical in landscape beds and small odd-shaped areas that are difficult to water with sprays, notes Mark Torkelson, president of Indiana Irrigation.

“Drip works well in applications where low water pressure and flow are all that is available,” he says. Randy Wildeman, owner/operator of Western Irrigation in Garden City, Kansas, notes that water quality and soils are key considerations when designing drip irrigation.

“We need to check the soil type and the annual rainfall so we know how to design that application,” he points out. “You can do just about any soil type for this.”

Other key design considerations include how much water is needed by different plant types based on their location as well as the tubes with integrated, evenly spaced emitters used to dispense the water and how and where they should be placed. Merriott favors drip irrigation in flower beds. “You can use it on a slope,” he says. “We like to put it in a grid pattern so the whole planting bed is covered. If you have containers, you can tie them onto the drip system.”

Merriott says if customers don’t feel like their drip system works well and end up with a poor overall experience, it could be because the installing contractor didn’t use enough product in the ground or pay attention to where the lines are. That can cause spots that aren’t getting coverage.

“If you have a really sparse bed with only a couple of plants, it’s fine to just put the drip where the plants are,” Merriott says. “A lot of people like to build their beds up to cover or fill them up with perennials or different plants. If that’s the case, they want to have the whole bed covered with the product.”

Installers need to know how many emission devices will be on the drip zone and the flow rate of each to properly size the tube, says Torkelson.

Installation considerations focus on water source connection and components. Some local codes may require a backflow preventer to protect the potable water supplying the house from contamination by the irrigation water.

When converting a flower bed from sprinklers to drip irrigation, Merriott’s crews will space the emitters about 12 inches apart and 18 inches between lines, which can achieve about 1 inch per hour precipitation rate.

Merriott uses mulch, wood chips or decomposed granite during installation, rathering than burying the lines.

“It’s difficult to see problems in a buried system,” he says. “You could have problems with root intrusion. If your water is not really clean, you can have clogging problems.”

Mulch also helps conserve moisture and decrease evaporation.

Benson notes in her water audits that some contractors aren’t putting in adequate pressure reduction through the valve system during installation.

“We’ve got extremely hard water in Florida,” she adds. “Once you put reduced pressure valves in there, they come with a filter that requires maintenance. Minerals build up because of the hard water and with low pressure, the water can’t get to the plants a lot of times.”

Operate for success

In operating a drip irrigation system, it’s necessary to know its precipitation rate, which is calculated on the flow rate and spacing of the emitters as well as the time of year, says Merriott.

“Our typical precipitation rate is about 1 inch per hour spread over the whole bed,” says Merriott. “If you have a 1 inch per hour precipitation rate and your plants need 1 inch of water per week, then you want to water your system for about an hour a week.”

If your system has a higher precipitation rate, adjust the time accordingly to meet the needs of the plants. State extension services are helpful in supplying that information, she says.

Time of day in running a drip irrigation system is not an issue, given there is less evaporation. “With sprinklers, we have water restrictions as far as what time of day we can water,” says Merriott. “Drip is exempt from our water restrictions because it really doesn’t matter what time of day you water. The amount that you water matters.”

Ground-level drip irrigation systems can sustain weed growth damage, clogged emitters, freezing pipes and damage from landscape work or animals.

Some property owners don’t want the maintenance responsibility of a drip system, Benson says.

“They just want it to work,” she says. It can also be an opportunity to sell regular maintenance checks to take care of that step for the client.

The drip system needs to be regularly monitored and inspected to see if there has been damage by rodents or humans to the system that cause leaks or clogging, Torkelson says.

“Also, some water sources are high in minerals and can cause clogging, so the system needs to be monitored for that,” he adds.

The biggest issue Merriott sees with drip irrigation systems is that squirrels like to chew on them.

To try to mitigate that, she uses mulch or large river rocks squirrels are unable to move.

Wildeman tells clients as long as chlorine or acid is run through the system once a year to clean it, the drip irrigation system is low maintenance.

“The only failure point is going to be if they do not do the maintenance; it causes issues with the system as far as it starting to plug up,” he says.

Merriott advises that systems are checked at least three times a year or more to ensure proper operation. Maintenance can depend on location and the water source.

“We have city water, which already has chlorine in it,” Merriott says. “But if you’re in a rural area and your water has bad stuff in it, you might need to flush it. In situations with well water, you might have to clean the sand out of the filters. We don’t put filters on most of our systems because it’s drinking water.”

Landscape professionals note the return on investment in a properly designed, installed, operated and maintained drip system is water efficiency and aesthetics.

Carol Brzozowski is a freelance writer with a specialty in environmental journalism based in Coral Springs, Florida. She can be reached at brzozowski.carol@gmail.com.