You’re on a site visit and the first thing you notice is the lackluster plants. There is a glaring difference in the same plant species’ height, color and vitality. Some look wilted, nearly dead, and others show signs of disease.
You know there’s a functioning drip irrigation system and wonder, what is going on?
When you’re out troubleshooting an existing system, see if one of these five mistakes might be to blame. When preparing to install a drip system, keep these common errors in mind to avoid callbacks or dissatisfied customers.
Installing it and walking away
Whether comprised of rotors and sprays or drip, an irrigation system is a mechanical system. And it’s sometimes considered “finished” upon installation. However, Declan Keane, owner of Life Source Irrigation Inc., a New York City-based drip irrigation specialist, disagrees.
Life Source specializes in rooftop gardens across Manhattan and Brooklyn. His clients include private residences, hotels, restaurants and property management companies with small- to medium-sized spaces along the buildings in front of Park Avenue, Central Avenue and Fifth Avenue.
He says the ideal situation is to check the system weekly and make decisions for repairs or adjustments in collaboration with a gardener or landscaper, if plant maintenance is outside your contract. He starts his weekly check-ins inspecting the plants and determining if any changes are needed.
“I like to run a deep watering twice a week in spring. Then I water every other day in the summer,” he says. “If you water heavily and then let the plants dry out, they do much better. You must factor in what type of plants and environment and make changes accordingly.”
In addition to checking plant health, it’s important to examine the system mechanics. For Keane, that specifically includes the drains.
“The rooftop gardens are 30 floors up, and you have to plan for the worst-case scenario,” he says. “It’s not like on the ground where the excess water from a broken pipe runs off. You could flood a place and do a lot of damage on a rooftop.”
Western New York-based irrigation and water management consultant Jim Navarra emphasizes that the same principle holds true for commercial sites with landscaped beds and planters at ground level. In addition to the points mentioned above, he added that other site contractors could disrupt a system. Without an inspection, it’s impossible to catch until the plants show signs of stress.
One client is a prominent grocer with more than 100 stores on the East Coast. It’s not uncommon to have utility workers, general contractors or municipal workers digging up curb lines or asphalt. The more “hands in the pot,” the more chances for breakdowns, he says.
“Not everyone considers what they are disturbing when they work along a curb line and can easily damage or break dripline pipe,” he says. “Also, seasonally changing planting beds can disrupt the system, so it’s essential to check on it to ensure it’s working properly.”
Mismatched watering needs
Plantings have specific and varying water needs. Without planning in the design phase, it’s common to overlook this detail. Keane suggests grouping plants with similar watering needs in the same zone. For example, put all the grasses together, annuals on another zone and succulents that require less water on a separate zone.
“The environments can even vary on the same building. One corner might be more sunny, another more shaded and another more windy,” he says. “You have to factor that into the settings and make adjustments.”
In the perfect scenario, Scott Todd, co-owner of Innovative Irrigation Solutions in Rochester, New York, says spaghetti tubing with emitters matched to individual plant needs is the best option. It allows for mixing 0.5 gph to a drier plant like boxwoods, 1 gph to plants like arborvitae that need more water and 2 gph emitters on thirstier plants.
Keane added that he installs filters on every job. It doesn’t matter how clean the water source is; dirt and debris get into the lines and clog the micropore filtration. At the end of the season, the system is drained and flushed to eliminate any particles in the lines.
“If you install dripline without using filters, you’ll end up with problems because no water source is 100% clean,” he says.
A drip irrigation design must consider tubing and emitter placement to provide the maximum moisture benefits to the root system, Navarra says.
“I often see dripline run along only one side of the plant,” he says. “It needs to be on both to provide equal coverage and have a healthy, well-balanced plant.”
How close the drip is located to the plant is just as important. For example, Navarra frequently sees drip in planter beds spaced 4 inches from the stump of a tree.
“The root hairs can’t absorb water that far out from the main stem,” he says.
The same principle applies when using microtubing and emitters in raised planters and hanging pots. Using only one emitter in the central ring of the planter doesn’t provide enough water for those plants along the perimeter. In these scenarios, Navarra recommends using microtubing to accommodate multiple emitters.
As a rule of thumb, he suggests using two to three emitters inside 16-inch to 20-inch diameter pots. He recommends spacing emitters about 10 inches apart in larger containers depending on the growing media.
One of the biggest errors Todd finds is mixing rotors, sprays and dripline all on the same zone. On some jobs contractors run out of zones and don’t want the added expense of upgrading the clock. But “we’ll be called to a site where we know there is drip irrigation and the client says it’s not working,”
he says. “We get there, walk around to the drip and find it’s running with sprinkler heads. There’s not enough pressure.”
Todd adds that proper placement is as important with the stakes to hold the drip in place as it is in the dripline layout. He spaces staples no more than 6 inches to 8 inches apart on the dripline for nearly every application to prevent the line from shifting. Driving them in at 45-degree angles anchors them into the ground securely, he says.
Misunderstanding soil media
Failing to understand or account for the planting media is a common mistake. Knowing the soil’s water holding capacity, evapotranspiration rates, soil percolation and absorption is critical. These can vary from one site to the next and even in different locations on the same site.
“I can’t emphasize knowing the growing media enough,” Navarra says.
If the soil media is a heavy mulch that retains water, you will have to limit watering. If it’s clay-based soil, it’s essential to know this soil type prevents water from being absorbed. Loamy soil allows the water to percolate through before the plant has time to absorb the moisture.
Too much or too little water can have negative consequences. Underwatering in hot, dry climates can lead to costly plant loss. However, regular site checks and supplemental hand watering create opportunities to make adjustments as needed at the first signs of stress.
“Overwatering tends to be the bigger issue,” Keane says. “My experience is that plants can get away with a lot less water than we think. You get more color, more flowers and blossoms, and less fungus and disease. You may have to supplement with hand watering, but it is worth the time and effort.”
Todd agrees that too much water is a common mistake on job sites. He only installs drip irrigation on new plantings and only runs the system for a few years, until the planting is established. On older plantings on his projects, a system may only run in August if there are drought conditions.
Inadequate pressure regulation
Pressure-compensating pipe is more costly upfront, but skimping at installation can have expensive long-term consequences. Without a pressure-compensating pipe, it’s impossible to maintain equal pressure from the head to the foot of the system, especially if it is not a looped system.
To guarantee the system has enough pressure, Todd limits each drip zone to 2,000 feet per 45 psi high-flow regulator. He runs 1-inch line off the valve then splits the zone sending tubing 1,000 feet in one direction and 1,000 feet in another dividing the area in the middle rather than looping from front to back on the property.
“We don’t reduce the main line down to one-half inch until we get to the middle to be sure we get equal flow on both sides,” he says.
The best practice is to plan each zone with consideration given to the water volume available, Navarra explains. Pressure and volume drop as the distance from the water source increases, and when run in excess of the water availability the result is uneven water distribution, which impacts plant health. Using friction loss calculations and manufacturer driplines specifications determine proper distance.
“Some people try to cheat on that rule because they think they can push water further down the pipe without the pressure regulator,” he says. “It might work, but it creates other problems. Dripline is not manufactured to exceed 35 to 40 pounds of pressure. Beyond that, you’ll start to get pipe failure.”
Drip irrigation lets you deliver water precisely where you want it. The systems are designed to provide a specific volume of water and nutrients where plants need it most, below the root zone. It limits moisture on plant material, reducing the opportunity for disease and fungus and providing equal water distribution.
But like anything, simply avoiding these mistakes is not a cure-all solution. Instead, it takes knowledge and frequent monitoring to leverage a drip system’s benefits. Brushing up on the properties of soil media, evapotranspiration rates and friction loss are your best bet for having the greatest success with dripline irrigation systems.