As the summer draws to a conclusion, gardeners should consider landscape installations in anticipation of the rainy season’s onset. Right now is the best time to plan new plants. The coming rains will keep them irrigated as they develop roots and prepare to bud out in the spring. The rainy season usually begins in mid-October, so we now have time to decide on new plants, find them in a garden center or online nursery, and acquire them.
Because half of California’s urban water use is for landscape irrigation, all gardeners should be conscious of their landscape’s water need and informed about the preferred ways to meet those needs. Last winter’s rains were pretty good and supported the growth of very satisfying gardens, but the long-term potential remains for water shortages.
For these reasons, this is also the right time to update your plans for water use efficiency.
California’s Model Water Efficient Landscape Ordinance (MWELO) “promote(s) the values and benefits of landscaping practices that integrate and go beyond the conservation and efficient use of water” and “establish(es) a structure for planning, designing, installing, maintaining and managing water efficient landscape in new construction and rehabilitated projects…”
This ordinance applies to new landscapes of 500 square feet or more and rehabilitated landscapes of 2,500 square feet or more when either project requires a permit.
Such large-scale projects require a detailed Landscape Documentation Package that must be signed by the responsible parties and an auditor. For detailed information, browse to the website of the California Department of Water Resources and search for “MWELO.”
Most landscape renovation projects are not extensive enough to have to meet the comprehensive requirements of this ordinance, but its thorough approach is worth informal consideration on a voluntary basis.
The key component of the Package is the appended Water Efficient Landscape Worksheet, which is used to estimate evapotranspiration, i.e., the water evaporated from adjacent soil and other surfaces, and transpired by plants, and to calculate the evapotranspiration adjustment factor (ETAF). The Worksheet guides the calculation of the ETAF which considers the major influences on the amount of water required by the landscape: plant factors and irrigation efficiency.
For residential areas, the ETAF should not exceed .55. This figure is then used to determine the Maximum Applied Water Allowance (MAWA) and the Estimated Total Water Use, which must be below the MAWA.
This explanation uses the minimum number of acronyms!
The simpler approach to efficient water use in the landscape involves two concepts. First, choose plants with lower water needs. The obvious choices are California native plants and succulent plants. Second, use drip irrigation to control the amount and location of water usage. The state provides a useful planning resource, “A Guide to Estimating Irrigation Water Needs of Landscape Plantings in California.” It’s available without cost from the California Department of Water Resources website. Search for “WUCOLS.” That one more acronym stands for “Water Use Classifications of Landscape Species.” The Guide document includes the water use needs of many garden plants, listed by both botanical and common names.
Planning for efficient irrigation helps to conserve the state’s limited water resources, and, for the gardener, minimizes the cost of water usage and supports effective plant growth.
This planning pays off!