Water Conservative Landscaping
By Denise Healy
For the Western gardener, having a beautiful garden landscape can be costly, in terms of both time and resources. Dazzling garden magazines, overflowing with blooms and lush vegetation, entice us at the check out line and local garden nurseries lure us with a kaleidoscope of colors and scents. Yet, while gardening in our climate isn´t easy, a little forethought given to working with our unique environment can yield gardens worthy of Sunset Magazine.
Most of us have to work with landscaping that was put in by previous owners. A good way to begin to work towards a low maintenance and water conservative landscape is to assess it. First identify and become knowledgeable about your plants and their basic needs. Then take the yard sector by sector and note how much sun and shade the area gets. Evaluate the soil on the property and its topography. And finally, consider problems with existing watering systems and see if there are ways to improve those systems.
It goes without saying that plants perform best when their individual needs are met. A great resource for gaining information about specific plants is the Sunset Western Garden Book. This reference book provides a wealth of information about plant types, their basic requirements, their deer resistance and other information to help make thoughtful, well informed decisions. Our local library has an abundance of books pertaining to plant specimens and landscape. Many have color photos to help with identification. Finding out what has worked (or not worked) for neighbors and friends is another good way to evaluate and plan.
When selecting new plants or considering the placement of old ones, work to match the plant with the area, placing “the right plant in the right place.” Place plants with similar needs in the same areas. Considering the mini zones of your yard, put thirsty plants in areas which will be watered more frequently, drought tolerant ones in dry areas and shade or sun loving plants where their needs are best met. This will save on watering costs and provide a landscape that is aesthetically pleasing. Sometimes moving plants to other areas will solve the problem but occasionally they just have to be discarded. Native plants, that is, plants that are indigenous to our climate and zones are an excellent choice when considering water conservation and relative ease in landscape care.
Soil and topography are important factors when calculating watering schedules. When watering clay soil on a slope, for instance, water begins to run off after just a few minutes. “Cycling” is a process used for watering on a slope which allows for absorption, keeping run off to a minimum. It is done by watering for short periods of time until water begins to run off, followed by short intervals with the water off, say 10 minutes on and 15 minutes off during the course of an hour (versus a straight half hour of constant irrigation). It takes more time, but reduces waste due to run off as it allows time for the water to penetrate into the soil.
Most plants will root as deeply as moisture and nutrients will allow, so watering deeply and infrequently encourages plants to send their roots deeper, making them less likely to wilt at the first heat wave. Essentially, effective watering gets water to the roots of the plant while avoiding run off or “urban drool.” Generally speaking, 1 inch of water will penetrate 4-5 inches into clay soil, 7 inches into loamy soil and about 12 inches into sandy soil. So, while clay soil holds water longer than sandy soil and can be watered less frequently, it does require more water at each watering session.
A good way to find out how much water is being delivered to the area is by doing a “catch can test.” This test can be done by placing identical low sided containers around the test area during a watering session (tuna cans work great for this!). Time the test for 5 or more minutes, then look at the cans to see how much water is in them. Significant differences in the amount of water in each can mean the watering system is not watering the area evenly.
This is a general guideline for figuring how much water is being applied to the area: For a 10 minute test, 45 ml. of water in the can will yield 1 inch per hour. To get ½ inch per hour, the can would have 20 ml. and 2 inches in an hour would have 90 ml. in the can after 10 minutes.
Mulching helps keep water in the soil, decreasing evaporation into the air. This is especially true for clay soils which tend to harden on the top layer, making it difficult for water to penetrate. It also keeps down weeds which compete with your plants for precious moisture.
When assessing watering systems, first make sure they are in good working order. Leaks are notorious water wasters and should be fixed. If the watering system is as simple as a sprinkler at the end of a hose, make sure it adequately covers the area, but doesn´t spill over onto non-vegetative areas. If the watering system is underground, be sure the heads work within the bounds of what is being watered. Drip irrigation delivers water to the roots of plants, reducing evaporative waste. Local nurseries and garden centers carry a wide variety of irrigation products. Again, the best advice is to do the research first before investing. All systems have their advantages as well as drawbacks.
Mother Nature, when she feels generous, waters the earth with abandon. We mere mortals however, have to be careful with our resources. Considering our own individual landscape needs and working with our environment will help us to have beautiful gardens which bring us pleasure while conserving our valuable time and resources.
The website http://earth911.org/water/water-conservation/ can offer more information about water conservation. Or call or stop by the Master Gardener office for further information.
Denise Healy is a new graduate of the Master Gardener program in Tuolumne County and gardens with her family in Columbia.