MASTER GARDENER: Landscape Water Conservation Is Up To You

Mar 4, 2011 by

Much talk these days has centered on water conservation. Doyle Wilson, Lake Havasu City Water Resources Coordinator, has put together an extensive document that details plans for future possible water shortages. This can be found on the City website at http://www.lhcaz.gov/brochures/publicworks/2010waterConservationPlan.pdf.
However, we should not wait for potential serious drought to occur. Increasing population and water demands will also reduce the available supply. And how about thinking of lowering your water bill? Proper landscape irrigation is the answer.
Xeriscaping is using plants that need small amounts of water. Unfortunately, we live here in homes that already have the landscaping planted, so utilizing xeriscaping is only an advantage when adding new plants. Accessing the City’s website, you may also find an excellent list of low-water need plants and trees, so I will not go into detailing all of those.
Keep several things in mind when using outdoor water. The absorbing roots of a tree are around the drip line or outer canopy of the tree and extending out from there. Not at the trunk. It is therefore better to have a level watering basin in a donut-shape. This is not necessary with smaller plants.
Also, the roots of a large plant or tree are usually down 3 feet or more. Medium plants, such as shrubs – 2 feet; small plants – 1 foot or less. This means irrigating long enough for the water to seep down that far. Poke a soil probe rod into the ground after irrigating. It will move easily through wet soil, but become hard to push when it reaches dry. If you are watering very shallow, you are not effectively reaching the roots. If you water beyond the root zone, it only means you are wasting water.
In Lake Havasu City most of us have difficult soil conditions. It will usually take at least 30 minutes for water to reach the 3-foot level. Plants also need a short drying out period in between watering, so a heavy spaced out watering is much better than frequent, short-time watering. Smaller plants may only need 20 minutes of irrigation. Normal desert plants, such as cacti and succulents, may only need irrigation once a month and that is if no rain has occurred.
In LHC, I would recommend watering once a week during the winter. For summer and late spring-fall, twice a week. During a lengthy period of extreme (145+) temperatures, you may have to do a third run. The length of time can vary according to the type of landscaping on the bubbler run and each bubbler can be adjusted for low or high flow. Note that if it rains more than ¼ inch, you can shut off the runs for a week. With a 1-inch rain, about two weeks. If possible, plant or replant landscaping so that all plants/trees on a given run need about the same amount of water. Also keep in mind that factors of soil type, slope, and exposure to sun must be considered.
Do not irrigate during the hot time of the day. But bubblers (which are the irrigation method of 95% of our homes here) can break or get stuck. Leave enough daylight at the start or end of the irrigation time to examine the systems. Because of the salt content in our water, a blocking salt layer can develop at the bottom of the usual water level. Once or twice a year, water the areas twice as long to leach the salt and break that layer.

Don Bergen is a Lake Havasu City Master Gardener. For more information or questions, call the Master Gardener hotline at 928-753-3788

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