Monday, June 20, 2011


Hose at the ready:
Thanks, Oak Island
            Tim and I have an in-ground irrigation system. I love it for convenience’s sake, because it frees me from dragging hoses and sprinklers around the yard. Or at least it did until our megalomaniacal town government forced The World’s Most Expensive Sewer System down our throats just because they want the 45-foot height restriction lifted so we can become Myrtle Beach.
            Be that as it may, I no longer use the irrigation system except for the drip zone. I’m back to hauling hoses to water the south-side nursery pots and any new planting that isn’t reached by dripline until it stops wilting. The lawn is on its own. Spray zones are inefficient anyway, as they are subject to wind and evaporation issues. Plus, I’m not totally convinced the perfectly manicured lawn—an artificial, high-maintenance monoculture—is such a great idea in the first place. (In Second Nature, Michael Pollan does a hilarious riff on his dad’s refusal to buy into the tyranny of grass in a Long Island suburb in the 1950s. See Good Reads at right.)
Mr. Pollan takes on the POA
in Chapter 1

Nonetheless, irrigation systems relieve the daily tedium of hydrating your landscape—just set the clock and let her go while keeping a weather eye out for, well, the weather. Of course, nothing yet devised by man is without its little hiccups. Lots of things can go wrong, starting with installation. Some installation contractors have a deep understanding of, indeed an affinity for, the hows and whys of irrigation mechanics. Others just stick pipe and wires in the ground and hope for the best.

Even flawlessly installed systems, however, can run into trouble for a number of other reasons. Programmophobia, the unreasoning fear of touching the controller, crops up with alarming frequency. Most clocks offer two or three programs, each of which has three possible start times. It’s important not to overlap start times, because when you do, no water comes out anywhere. You’ll need to know how to set zone run-times and water days for every program you use. It’s also important to know how to run the system manually, both from the clock and at the valves. This is essential because how much and when you’re watering what changes fairly often. Why’s that? you ask. Because water requirements change over time. Well-established lawns and shrubbery need less (or no) supplemental irrigation, especially in cool seasons. For those of you who keep adding plants like I do, drip is pretty much forever. You’ll also need to know how to change the back-up battery that lives inside the clock, which saves your watering program for 24 hours should you lose power for any reason. The battery cannot run the system, however, so get in the habit of checking both the controller and the ground-fault-interrupter outlet it’s plugged into after every thunderstorm and whenever you have to reset your microwave clock.

A few other common irrigation aggravations include:
The Fitzgeralds' Nelson
irrigation computer-clock

·         Rain sensors. These excel at sensing rain and turning the system off but to date have proven lacksidaisical about turning things back on after the rain stops. Glenn, our irrigation guy, assures us they’re getting better. Uh-huh.

·         People operating vibrating plows, trenchers and core aerators. All these pieces of equipment can (and do!) cut through, shatter and/or puncture hard pipe and driplines without anyone’s knowledge until the grass and shrubs start to go brown and crunchy despite the fact that new wetlands seem to be forming out at the front of your property.

Watch out for this guy
with his Dingo trencher

            ·         Thirsty rodents. Squirrels regularly splash all the water out of  the bird bath I installed expressly for their convenience and enjoyment, then gnaw holes in my driplines to get a drink. Flirty-tailed little bastards. And the raccoons are just as bad.

            ·         Summer vacations. If anything is going to go terribly wrong with your irrigation system, it will happen when you’re out of town. Ask someone you trust to check on things inside and out while you’re gallivanting. Especially after thunderstorms.

the most efficient way to water

In irrigation as in life you get what you pay for. An all-drip system—one without any spray heads, even for the lawn—is the most cost-over-time and water-use efficient way to go. It is also the most expensive initially, even assuming you find a contractor who’s heard of all-drip irrigation and knows how to install it. Be aware that quality of materials varies significantly. Heads range from el-cheapo plastic to top-of-the-line brass. Although none of them lasts forever (imagine grains of dirt grinding away at moving parts every time a head pops up, rotates and retracts), the replacement interval for the higher-quality models far exceeds that of bargain-basement specials. The basic system is a sprays-for-grass-and-drip-for-garden-areas array. Insist on a zone dedicated to dripline, for three reasons: 1) many plants, like roses and azaleas, resent overhead watering as this practice promotes fungal growth and sun-scorched foliage; 2) at some point you’re going to be able to drastically reduce the water you give your grass, and where does that leave all those garden areas serviced by the same zone?; and 3) do you really want to make life easier for those weeds in your “natural” areas?

For your information, a turf head—the large, rotating sprayer—spews out about two-and-a-half gallons a minute. Spray heads—the smaller ones that water in a constant arc—throw out four or so gallons a minute. Neither of these figures accounts for evaporation or wind dispersal. If time hangs heavy on your hands, you can count the number and type of heads per zone and multiply by the appropriate gallons-per-minute to determine how much water comes out: divide the number of gallons by the square footage of the area (rough length by approximate width—it’s easier if you make everything a rectangle) to learn how much water you’re providing per square foot per cycle. You’ll probably be appalled.

Turf head spewing
two-and-a-half gallons per minute
while rotating 180 degrees

Spray head (on a riser)
blowing out four gallons per minute
in a fixed arc

Emitters and the special
emitter tool for making holes
in the drip pipe
(the red-top one is an 8 liter,
the green-bottom one a 1 gallon 

Driplines have little button- or spigot-like things stuck into them, called emitters, where the water comes out.  They are calibrated to release two gallons/eight liters per hour or one gallon/four liters per hour. You can tell which ones you have by peering closely at the thing—it has a teeny-tiny 2 or 8, or a 1 or  4 stamped on it somewhere. Emitters should be placed well away from the main stem of the plant but still within the rootball area. How long and how often you run the drip zone depends on the number, placement and output of the emitters, and on your soil type.

While a well may seem an attractive alternative to connecting to municipal sources, the hidden costs of “free” water can be prohibitive. Mainly, you have to worry about the pump. In my neighborhood, irrigation-only wells tend to be shallow, and the pump ends up above-ground, usually in an aesthetically inappropriate place. Pump installation quality varies as much as that of irrigation systems themselves, and for the same reasons. Preventing cracked lines during winter is another headache. Because watering during the cold months in mild-winter areas is essential for newly installed plants and shrubs, you can’t just winterize the pump and turn it off. Anti-freezing devices that involve electricity (heat-tape, light bulbs, etc.) are subject to the vagaries of the power grid. You can also count on dirt getting drawn up with the water, so your driplines will need to be blown out once or twice a year to prevent them from clogging up. (Do this by removing whatever crimps the end of the line, then run the zone for a minute or two.) This is especially true if you use quarter-inch tubing to irrigate your containers—these plug up in no time at all. Emitters at the ends of these "spaghetti" lines may also become obstructed, reducing—or nullifying—their effectiveness.           

An unburied and unmulched
dripline in my back yard

By the way, driplines should never be buried, only covered with mulch. Over time, however, mulch and dead leaves decompose, turning into soil. Tiny surface roots work their way over your dripline and grow into bigger surface roots. My point is that, left to her own devices, nature buries driplines. It’s really to your advantage to keep them up on the surface where you can easily get at them to add or subtract emitters and line extensions.

 That’s all I have to say about computer-controlled irrigation systems. Have additional questions? Totally confused? Leave a comment, or email me, and I’ll try to clarify the murky area.

Oak Island got .34" more rain on Saturday, bringing us up to a half-inch for June. Next time: rain gardens and water harvesting. Thanks for dropping by.


P.S. – Summer solstice occurs on the 21st at 1:16 pm EDT. It feels so ironic that the days begin to shorten when it’s so damn hot out, don’t you think?