Friday, July 9, 2010

Water Misers and Naughty Nuns

As the sun beats down on us and our landscapes in these summer months, we should be mindful that we are the deacons of our limited water supply. As a licensed irrigator, landscape designer, and student of Landscape Architecture, I field questions on all fronts about how often one should water their lawn. This is a tricky question. I simply don’t know how fast your system puts out water. The only way to do this is to throw out catch cans and measure precipitation rates. Sadly, this almost never happens, so instead, I’ll attempt to give you rough estimates for your system. To best explain this, I’ll break it down into four different systems and two management techniques.

Older systems with brass nozzles put out faster than a hooker on Harry Hines. They’re fast and I mean torrential downpour fast. Our heavy clay soils shed water quickly, so apply 3 or 4 minutes at a time or it will start running down the street. At high temps, weekly, I would water St. Augustine 4 times and Bermuda 3 times.

Newer systems with plastic nozzles still put out, but more like a bride on her wedding night. I recommend 20 minutes a week for St. Augustine and around 15 for Bermuda, and then divide by the number of days you want to water, either 2 or 3.

Even better yet are the MP Rotator Nozzles which are very good for the environment. These put water out very slowly, so think 20 years of marriage. I would run these around 25 minutes twice a week for St. Augustine and 20 minutes twice a week for Bermuda. See image below.

Our last system uses drip lines to deliver water to plants. At .6 gallons per hour per emitter, think slightly naughty nun. At this point in technology, it’s hard to beat the drip. Unfortunately, the water needs of perennials vary, so my advice at this point is to torture your plants. Start at 10 minutes per day and work backwards until your plants show signs of stress then back up a notch... 9 minutes, then 8, then 7, “Whoa, I didn’t know my plant knew that kind of language… We’ll go back up to 8.”

All of this is good, but management is where water conservation starts. The little box on the wall is the biggest water bandit of the landscape.

Our first management technique is to make you the controller. Why? Because unfortunately, there are no residential controllers on the market that know there’s rain in Tarrant County heading your way and that delay watering. My best advice is to keep the controllers in the OFF position and use the AUTO for vacation. Allow Mother Nature to do the work for you and supplement those dry spells when needed.

For those who prefer the hands off approach, you can invest in an “Evapotranspiration (ET)” controller. These “Smart” controllers measure the atmospheric conditions and use historical information based on your zip code then adjust the programming for you. While not as good as a diligent water miser, these controllers are years ahead of the “dumb” controllers widely used today. For those living in the DFW area interested in paid landscape consultations or design, you can reach me at 214-704-1291. -Jason

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