Drip Irrigation: How Long Do I Water?

     90% of all plant problems are water related, either too much or too little. Compounding the problem: gardeners who are operating a drip irrigation system but using a sprinkler mentality.

     Callers to the radio show, after describing a plant problem will be asked: "How are you watering that plant?" More often than not, if the answer is, "drip irrigation", they will follow that with, "And I run it for five minutes a day, everyday."

And therein lies the problem.

     A drip irrigation system puts out water much slower than a sprinkler system, usually a gallon or two an hour versus a sprinkler system's output of a gallon or two A MINUTE.

     In five minutes, a 1 gallon per hour (gph) drip emitter will put out about 10 ounces of water...slightly more than a cupful. Not only will that pittance of water not saturate the width of the plant's root zone (which can extend beyond the canopy of the plant), it won't penetrate more than an inch or two. And then not stay there very long.

     What happens to a plant with a shallow watering program? The roots stay very near the surface, where they are more subject to drying out quickly. This boom and bust cycle stresses the plant, opening up the possibility of disease and insect invasions.

     With a drip irrigation system, don't think "minutes". Think: "hours". And water deeply, but infrequently (once or twice a week).  

Your goal is to apply enough water to penetrate the soil to a depth of at least 8 inches, preferably more. The day after you water, either dig down 8 inches by hand or with a soil sampling tube; or, stick a moisture meter down to that depth to determine if the soil is moist (not dry, and not soggy). Battery-operated soil moisture meters (such as the yellow one, pictured on the right) tend to have a longer life.

In our raised bed vegetable garden, the summer watering regimen is with an inline drip irrigation system (1 gph emitters along the line, spaced 12" apart) which is run twice a week, six hours at a time. Your weather, soil type, slope and crops may need a slightly different watering schedule. In our 4'x20' raised beds, three inline emitter lines run the length of each bed. The lines are spaced 18" apart.

Consider using microsprinklers or sprayers to thoroughly wet the root area for trees and shrubs. These put out more water, usually between 8 and 20 gallons per hour. We have these on our shrubs and fruit trees, and during the summer will run them for about an hour, once or twice a week, depending on how hot it is.

     The other part of the drip irrigation equation that a lot of gardeners miss: not enough emitters for the plant. Placing one emitter next to a new tree or shrub is not enough. Remember, plant roots tend to grow out horizontally. Emitters should be spaced evenly around the tree or shrub, in a circle, halfway between the trunk and the outer canopy of the newly installed plant. The spacing between the emitters will depend on your soil type: for sandy soils, use a 12" spacing; for heavy clay, 18-24" spacing. Add emitters towards the outer canopy of the plant as the plant grows.

  

• Soaker hoses need maintenance, too. Flush them monthly. The Dramm soaker hose, pictured here, is the most reliable, even-flowing soaker hose I have ever used.

A great online tutorial of drip irrigation: the Dripworks website. This site has helpful tips and videos that can help beginner and pro alike solve their drip irrigation and yard watering woes.

     The Dripworks catalog is also great resource for anyone tackling the problems associated with drip irritation...uh, irrigation. Just thumbing through the catalog can give you several "Aha!" moments for improving your own yard watering procedures, especially if you are looking to replace your residential sprinkler systems with a drip irrigation system, which can work with your existing automatic sprinkler system control box.

How Long To Run a Drip Irrigation System?

     90% of all plant problems are water related, either too much or too little. Compounding the problem: gardeners who are operating a drip irrigation system but using a sprinkler mentality.

     Callers to the radio show, after describing a plant problem will be asked: "How are you watering that plant?" More often than not, if the answer is, "drip irrigation", they will follow that with, "And I run it for five minutes a day, everyday."

And therein lies the problem.

     A drip irrigation system puts out water much slower than a sprinkler system, usually a gallon or two an hour versus a sprinkler system's output of a gallon or two A MINUTE.

     In five minutes, a 1 gallon per hour (gph) drip emitter will put out about 10 ounces of water...slightly more than a cupful. Not only will that pittance of water not saturate the width of the plant's root zone (which can extend beyond the canopy of the plant), it won't penetrate more than an inch or two. And then not stay there very long.

     What happens to a plant with a shallow watering program? The roots stay very near the surface, where they are more subject to drying out quickly. This boom and bust cycle stresses the plant, opening up the possibility of disease and insect invasions.

     With a drip irrigation system, don't think "minutes". Think: "hours". And water deeply, but infrequently (once or twice a week).  

Your goal is to apply enough water to penetrate the soil to a depth of at least 8 inches, preferably more. The day after you water, either dig down 8 inches by hand or with a soil sampling tube; or, stick a moisture meter down to that depth to determine if the soil is moist (not dry, and not soggy). Battery-operated soil moisture meters (such as the yellow one, pictured on the right) tend to have a longer life.

In our raised bed vegetable garden, the summer watering regimen is with an inline drip irrigation system (1 gph emitters along the line, spaced 12" apart) which is run twice a week, six hours at a time. Your weather, soil type, slope and crops may need a slightly different watering schedule. In our 4'x20' raised beds, three inline emitter lines run the length of each bed. The lines are spaced 12" apart.

Consider using microsprinklers or sprayers to thoroughly wet the root area for trees and shrubs. These put out more water, usually between 8 and 20 gallons per hour. We have these on our shrubs and fruit trees, and during the summer will run them for about an hour, once or twice a week, depending on how hot it is.

     The other part of the drip irrigation equation that a lot of gardeners miss: not enough emitters for the plant. Placing one emitter next to a new tree or shrub is not enough. Remember, plant roots tend to grow out horizontally. Emitters should be spaced evenly around the tree or shrub, in a circle, halfway between the trunk and the outer canopy of the newly installed plant. The spacing between the emitters will depend on your soil type: for sandy soils, use a 12" spacing; for heavy clay, 18-24" spacing. Add emitters towards the outer canopy of the plant as the plant grows.

  

• Soaker hoses need maintenance, too. Flush them monthly. The Dramm soaker hose, pictured here, is the most reliable, even-flowing soaker hose I have ever used.

 




A great online tutorial of drip irrigation: the Dripworks website. This site has helpful tips and videos that can help beginner and pro alike solve their drip irrigation and yard watering woes.

     The Dripworks catalog is also great resource for anyone tackling the problems associated with drip irritation...uh, irrigation. Just thumbing through the catalog can give you several "Aha!" moments for improving your own yard watering procedures, especially if you are looking to replace your residential sprinkler systems with a drip irrigation system, which can work with your existing automatic sprinkler system control box.

The Farmer Fred Drip Irrigation Video

Drip Irrigation vs. Drip Irritation

    Anyone who has ever struggled with a drip irrigation system in their yard may believe that the term "irrigation" may be a misnomer. The tendency for such systems to be plagued with clogged emitters, broken pipelines and incompatible components may lead one to consider renaming this watering headache as "drip irritation".
    The biggest benefit using a drip irrigation system is that water is not wasted. The emitters can be placed directly on the plants' root zones, insuring that the plant - not the surrounding weeds - get the water. And less water wasted can translate to lower water bills.
    There is, however, a trade-off: unlike sprinkler systems, drip irrigation components, connectors, lines and emitters should be checked more often and more thoroughly to make sure the system is flowing correctly. And problems can pop up all along a drip line:

• Dirt, sand or bugs can clog the in-line filter screens, preventing water from leaving the faucet; they can clog individual emitters as well. 

• An errant mower or weed whacker may have sliced and diced your 1/2-inch or 1/4-inch pipelines as well as your emitters. 

• Connectors may have worked loose in the heat, sending water gurgling down the driveway. 

• Replacement parts may not fit correctly; so, back to the hardware store you have to go.

    If you are willing to work at it, drip irrigation can be a worthwhile investment. Some tips I've learned the hard way over the years:

• The best purchase? An inline emitter system. This half-inch poly pipe has one gallon per hour emitters built into the inside of the pipe, usually spaced 18" apart. These pressure compensating emitters flow evenly, with little if any blockage. Plus, you can't accidentally weed-whack off the emitter. Different spacings and different gph emitters are available on inline systems.

• Not all half-inch, five-eighths or three-quarter inch poly pipe is created equal; you'll find this out in a hurry when the connector doesn't slip on easily...or is too loose. Different manufacturers have different diameter pipe. For half-inch it could range in an outside diameter from .620 to .710. If you are not sure what size you have when you go shopping for more poly pipe, take one of the slip connectors from your existing system with you.

• Those connectors (slip, corners, tee's) may have different colored rings on the end for a reason: they fit on different sized half-inch pipe, specifically, Raindrip. One solution if faced with different sized mainline pipe: purchase adjustable connectors.

  • Know the difference between pipe thread and hose thread parts; otherwise, you won't get a tight fit and leaks will occur. If you're connecting to an outdoor faucet, make sure the anti-siphon valve, pressure regulator and female faucet attachment are hose thread parts. Attachments to PVC pipe parts should be pipe threaded. Usually, the letter "p" or "h" in the part's serial number is your best indication.

  • Use filter screens. Check them for debris on a regular basis. If you use y-shaped filters (which make fertilizing chores a snap), flush them out once a month.

  • If your water supply is turbid (contains dirt particles), stay away from half-gallon emitters. These are too quick to clog.

  • Remove the end cap and flush the entire system at least twice a year.

  • If you bury your 1/2-inch dripline (which can protect it from the corrosive rays of the sun), make sure you know where it's buried. Otherwise, an errant spading fork or rototiller may turn your line into Swiss cheese.

* And keep your weed whacker away from any emitters.

 Most common mistakes gardeners make when converting to drip systems:

• Incorrect watering times. Drip systems that use one gallon or two gallon per hour emitters need to run for hours at a time, not minutes. In my raised bed vegetable garden, the summer watering regimen is twice a week, six hours at a time. Your weather, soil type, slope and crops may need a slightly different watering schedule. In my 4'x20' raised beds, three inline emitter lines run the length of each bed. The lines are spaced 18" apart.

• Not enough emitters for the plant. Placing one emitter next to a new tree or shrub is not enough. Remember, plant roots tend to grow out horizontally. Emitters should be spaced evenly around the tree or shrub, in a circle, halfway between the trunk and the outer canopy of the newly installed plant. The spacing between the emitters will depend on your soil type: for sandy soils, use a 12" spacing; for heavy clay, 18-24" spacing. Add emitters towards the outer canopy of the plant as the plant grows.

• Too much water pressure. Most drip systems will work fine with just a quarter turn of the outdoor faucet, around 25 psi. Too much pressure, and you could blow out the connections and the emitters. If you have your drip system connected to your automatic sprinkler valve system, be sure to use a pressure regulator.

• Too long a run of dripline means not enough water flow. Try to keep runs of half-inch polypipe with one gallon per hour emitters spaced 18" apart to under a 100'. Bigger emitters or closer emitter spacing? Reduce the run even more. If I'm doing a long run from a faucet to the beginning of a drip area, I'll install 3/4" or 5/8" mainline poly pipe from the faucet to the beginning of the garden area, and then reduce the pipe size to the half-inch inline emitter tubing.

• Consider using microsprinklers or sprayers to thoroughly wet the root area for trees and shrubs. These put out more water, usually between 8 and 20 gallons per hour.

• Monitor the system. "Walk the lines" regularly during an irrigation cycle, making sure that all the emitters are working and there are no leaks.

• Soaker hoses need maintenance, too. Flush them monthly.

A great online tutorial of drip irrigation: the Dripworks website. This site has helpful tips and videos that can help beginner and pro alike solve their drip irrigation and yard watering woes.

     The Dripworks catalog is also great resource for anyone tackling the problems associated with drip irritation...uh, irrigation. Just thumbing through the catalog can give you several "Aha!" moments for improving your own yard watering procedures.

   

Dog vs. Drip Irrigation

I'm not sure what the attraction is, but dogs and water find each other, wayyyyy too often. We've had more than one sprinkler mangled by our dog. Probably a combination of thirst, playfulness and boredom. Our sprinkler solution: put a tomato cage around the sprinkler head to keep a few inches separation between nozzle and muzzle.

     Les in Gold River has his own doggone water issue:

     "We are dog sitting my in-law's dog for awhile," Les writes. "I was thinking of re-doing my drip irrigation this year, but now my in-laws' dog has done my thinking for me by ripping up sections of the drip line. So before I try to put something back in place, is there something that you can recommend that I try that does not encourage dogs to chew it up?"

     You mean other than blame the psychoses of your in-laws for screwing up the dog? Nah, that's too easy. Other than burying the line, I can't think of any other deterrent; installing an enclosed dog run in another part of the yard, perhaps. You may want to check with the Dripworks website to see if they have any dogproofing ideas.

     The Dripworks catalog is a great resource for anyone tackling the problems associated with drip irritation...uh, irrigation. Just thumbing through the catalog can give you several "Aha!" moments for improving your own yard watering procedures. And the Dripworks online site has helpful tips and videos that can help beginner and pro alike solve their drip irrigation and yard watering woes. (note: I was not compensated for this endorsement, damn it.)

     And that includes a helpful staff. I sent a copy of Les' e-mail to Cathie Nicolaus at Dripworks. And she responded:
     "I experienced my lab puppy doing the same thing, she liked the emitters the best because of the water spraying out. I had to redo my entire system on the deck! Here is something to try: Get a spray bottle and mix cayenne pepper powder and warm water and spray on the area that the dog is going for. You may have to make a small offering of tubing for the dog to get the idea, but he should rather quickly. For squirrels, we have in the past recommended petroleum jelly and cayenne pepper mixed together if you need to have it last longer on the tubing. In retrospect for our dog situation, I would have used the petroleum jelly/cayenne pepper mix around the emitters (being careful not to plug any holes) and tubing, since the water from the emitters was attracting the dog."