For The Answer
Weekly Express-News Article
Saturday, March 11, 2006
By Calvin R. Finch, PhD, SAWS
Water Resources Director, and Horticulturist
“A Special Irrigation Initiative is not Recommended”
After several years of cooperation and relative unity among horticulturists on the question of reducing water use on our landscapes, there are some cracks in the alliance. Some horticulturists believe that the ten month period of drought we have experienced in 2005 and 2006 is a major threat to our landscapes and the answer is to irrigate with a vengeance to save our lawns and trees. The problem with that strategy, of course, is that we will be irrigating our lawns at the same time as area farmers are irrigating their corn and other crops. The net result will be that the aquifer will fall to 650 feet and drought restrictions will be imposed.
I am on the side of the large numbers of plant people that are recommending moderation. I believe your landscape will survive well and your investment will be protected best by following the usual pattern of irrigating St. Augustine grass once every three – four weeks until June (if we do not receive rain). The strategy will also postpone aquifer drops and give us time to receive some rain. If we begin watering every week now, at the same time as the farmers are irrigating their crops, we can expect to move into drought restrictions very quickly.
Here are my reasons for thinking moderation.
Most plants in our landscapes are well adapted to periods of drought.
If they are well established, they have capabilities to survive
long, severe droughts. Live oaks,
· We only had about 16 inches of rain in 2005, half our average for the last ten years, but we also had four wet years before last year. The trees and shrubs have had a long period of “plenty” to store nutrients and prepare for stress.
· Even last year, despite the lack of total rain, did not stress plants as much as expected. It was a cool year and rains were relatively well timed. Rains in July helped keep per capita water use at a very low rate of 130 gallons/person/day. Landscape plantsprospered despite limited rains.
· It is true that some evergreen plants (including ligustrum, primrose, jasmine, and even oleanders) are showing stress due to drought, but that may be a result of lush growing conditions last spring and over the last four years. Most plants, including these evergreens, will adjust to the conditions and survive.
Anecdotal claims of plant death only become evidence of amajor threat
when the numbers are actually measured and compared to other years.
Plants die every year in
· Dormant plants do not use very much water. They are particularly capable of surviving a dry winter. Check out the shadetrees and shrubs in your neighborhood. Many are leafing out. Do you see any major abnormalities? The major stress will come later in the summer. Save the irrigation water and your budget for them.
Advisory Committee (CAP) meets next week.
The CAP reviews and monitors water resource projects. The Chairman is