Saving Water In Landscapes In California

There are a number of ideas that need to work together in order to unprotected to a water-saving scenery design and installation. These include:

Planting-choose mostly plants that have some drought resistance and need watering perhaps 1 to 4 times per month in the summer. group plants together which have similar watering requirements. Plants that need more water can often be used in special areas, to give some punch to entries, for example.

Irrigation-Group valve circuits by hydrozones so you water appropriately for each area.

For spray and rotor irrigation, carefully layout and adjust heads to avoid overspray, and use equaled precipitation rate heads on each circuit. For drip irrigation, use installation methods that limit the fragility of the system-spaghetti tubing, for example is easily broken. Drip emitter locations should be additional and subtracted as plants grow. Consider weather-sensitive “smart” controllers, such as subscription or stand-alone weather sensor packages. With or without these kind of controllers, pay attention to the programming of the clock-this is where more water gets wasted than anywhere else (turn it off during the rainy season in Northern California!).

Mulches-use 2 to 3 inches thoroughness of bark or arbor chip mulch to slow evaporation and keep the soil from baking. Arbor chip mulch is a way to recycle tree waste. Shredded bark is good on slopes as it doesn’t move down the slope as much as bark chips. Avoid “gorilla hair” which can form a mat that water and air have hard time penetrating.

Compost-Using compost as a top dressing for new and established plants, and in some soils as a soil amendment, will over time enhance the water holding capacity of soils. Compost can be mixed with bark or arbor chips as a mulch.

Question: Is drip irrigation better than spray?

Drip irrigation was originally developed for row crops, which are mostly annuals, then became popular for scenery plantings. Despite its popularity, it has some drawbacks, and each character owner or manager needs to make informed decisions when a scenery installation is planned.


  • Easy and comparatively inexpensive to install. Often no trenching is needed as the poly tubing is laid on grade, under the mulch.
  • Takes less training for workers to learn installation
  • Reduces evaporation when system is running-no spray or fogging to evaporate
  • For widely spaced plants, saves water since emitters are placed right at the root ball of the plant.
  • Easy to repair.


  • Fragile and easily broken. Often the problem isn’t seen until the plant wilts.
  • Some plants do better with spray on their leaves.
  • In heavy soils, can cause roots to decay due to sitting in water, as all the water is concentrated at the rootball. Some experts think CA natives are particularly susceptible.
  • As shrubs and trees grow, position and number of emitters needs to be changed-but this is rarely done. A 10-year old tree with emitters right at the trunk is not being helped by the drip system, and may be harmed.

A traditional spray system is more expensive and will not be as efficient, but will be sturdier, require less maintenance, and need less renovation as the scenery matures. use of bubblers in small areas is also a good choice. There is no one perfect system.

Question: What is xeriscape?

Xeriscape is a term for low-water use gardens and landscapes, also called drought-tolerant landscapes (“xeric” method ‘dry”, from the Greek information “xeros”). (It’s sometimes misheard as “zeroscape”.) There are many trees, shrubs, and groundcover plants that can thrive on much less water than the typical lawn and azaleas kind of design, which is a style well-appropriate to rainy climates but not to much of California with its 6-month dry period each year, or to the U.S. Southwest. In California, many public agencies rely on the WUCOLS database (Water Use Classification of scenery Species) to classify ornamental plants by high, medium, and low water use.

While there is a stereotype of xeriscape as either being limited to cactus and succulents, or limited to plants that look scraggly and unkempt, this is not true. Aside from California natives, there are many useful plants from similar climates such as Australia, New Zealand, South Africa, and the Mediterranean countries. While some California natives respond to drought stress by going idle or semi-idle in the summer, many will continue to look good with once-or-twice monthly watering. As in any planting design, attention to soil, exposure, slope, maintenance requirements, and the art of combining plant species will go far in creating a successful low-water scenery.

Question: what is the California State WELO?

The California State Legislature updated its scenery water conservation law by passing the WELO (Water Efficient scenery Ordinance), effective in January 2010. All new and renovated planting that totals over certain square footages must comply with the law’s water conservation requirements. This is a form ordinance-cities and counties may adopt stricter rules but not less strict rules.

The following projects fall under the new law (there are some exceptions but this covers most projects):

(1) new construction and rehabilitated landscapes for public agency projects and private development projects with a scenery area equal to or greater than 2,500 square feet requiring a building or scenery permit, plan check or design review;

(2) new construction and rehabilitated landscapes which are developer-installed in single-family and multi-family projects with a scenery area equal to or greater than 2,500 square feet requiring a building or scenery permit, plan check, or design review;

(3) new construction landscapes which are homeowner-provided and/or homeowner-hired in single family and multi-family residential projects with a total project scenery area equal to or greater than 5,000 square feet requiring a building or scenery permit, plan check or design review

observe that the square footages refer to planted areas, and do not include hardscape.

The law sets out the requirements for what should be included on Grading, Irrigation, and Planting Plans, (the whole ordinance is 41 pages!) but most important is the required calculation of MAWA (Maximum Applied Water Allowance, in gallons per year) and ETWU (Estimated Total Water Use), and ETWU has to be less than MAWA. Plant factors for these calculations are to be gotten from the WUCOLS (Water Use Classification of scenery Species) document.

Also of observe in the law: no overhead irrigation in areas narrower than 8 feet wide. Irrigation clocks must be connected to soil moisture sensors or Et (evapotranspiration) sensors, in addition as appropriate rain, freeze, and wind sensors. Many manufacturers are selling either subscription sets that download weather information to the controller, or stand-alone weather sensors that measure solar gain and rainfall on site.

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