There are a number of ideas that should work together to achieve a water-saving landscape design and installation. These include:
Planting: Choose mainly plants that have some resistance to drought and need watering, perhaps 1 to 4 times a month during the summer. group plants that have similar watering requirements. Plants that need more water can often be used in special areas, to add a touch to doorways, for example.
Irrigation-Group of valve circuits by hydrozones so that you can water properly for each zone.
For sprinkler and rotor irrigation, carefully position and adjust the heads to avoid overspray, and use matching rainfall rate heads on each circuit. For drip irrigation, use installation methods that limit the brittleness of the system – spaghetti tubing, for example, breaks easily. The drip emitter locations should be added and subtracted as the plants grow. Consider weather-sensitive “smart” controllers, such as subscription or standalone weather sensor packages. With or without these types of controllers, pay attention to the clock setting – this is where more water is wasted than anywhere else (turn it off during the rainy season in Northern California!).
Mulch – Use 2 to 3 inches deep of bark or tree chip mulch to slow evaporation and prevent the soil from baking. Tree chip mulch is a way to recycle tree debris. Shredded bark is good on slopes as it doesn’t sink as low as bark chips. Avoid “gorilla hair” which can form a mat that water and air have difficulty penetrating.
Compost – Using compost as a compost for new and established plants, and in some soils as a soil amendment, will improve the water holding capacity of the soils over time. Compost can be mixed with bark or tree shavings as compost.
Question: Is Drip Irrigation Better Than Sprinkling?
Drip irrigation was originally developed for row crops, which are mostly annuals, then became popular for garden plantings. Despite its popularity, it does have some drawbacks, and every homeowner or property manager must make informed decisions when planning a landscaping installation.
- Easy and relatively inexpensive to install. Often times, no trenches are needed as the polyethylene pipe is placed in the ground, under the mulch.
- Requires less training for workers to learn installation
- Reduces evaporation when the system is in operation, without spraying or fogging to evaporate
- For widely spaced plants, save water as the emitters are placed right on the root ball of the plant.
- Easy to repair.
- Brittle and easy to break. Often times, the problem is not seen until the plant withers.
- Some plants do better with spraying on their leaves.
- In heavy soils, it can cause the roots to rot due to settling in the water, as all the water is concentrated in the root ball. Some native CA experts are particularly susceptible.
- As shrubs and trees grow, it is necessary to change the position and number of emitters, 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 damaged.
A conventional spray system is more expensive and will not be as efficient, but it will be stronger, require less maintenance, and require less renovation as the landscape matures. Using bubblers in small areas is also a good option. There is no perfect system.
Question: What is xeriscape?
Xeriscape is a term for low water use gardens and landscapes, also called drought tolerant landscapes (“xeric” means “dry”, from the Greek word “xeros”). (It is sometimes misunderstood as “zeroscape”). trees, shrubs, and groundcover plants that can thrive with much less water than the typical lawn and azalea type of layout, which is a style well suited for rainy climates but not much of California with its dry period of 6 months each year, or southwestern US. In California, many public agencies rely on the WUCOLS (Water Use Classification of Landscape Species) database to classify ornamental plants by high, medium, and low water use .
While there is a stereotype of xeriscape as limited to cacti and succulents, or limited to plants that look scruffy and unkempt, this is not true. Aside from the 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 staying dormant or semi-dormant in the summer, many will still look good with watering once or twice a month. As with any plantation design, attention to soil, exposure, slope, maintenance requirements, and the art of combining plant species will go a long way toward creating a successful low-water landscape.
Question: what is the California state WELO?
The California State Legislature updated its landscaping water conservation law by passing the WELO (Water Efficient Landscaping Ordinance), effective January 2010. All new and renovated plantings that exceed certain square footage must comply with the water conservation requirements of the law. This is a model ordinance: cities and counties can adopt strict rules, but not less strict rules.
The following projects are subject to 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 landscape area equal to or greater than 2,500 square feet that require a construction or landscape permit, plan verification, or design review;
(2) Developer-installed new construction and rehabilitated landscaping on single-family and multi-family projects with a landscape area equal to or greater than 2,500 square feet that require a building or landscape permit, plan verification, or design review;
(3) New construction landscaping that is provided by the owner and / or contracted by the owner on single-family and multi-family residential projects with a total project landscape area equal to or greater than 5,000 square feet requiring a building or landscaping permit, plan verification or design review
Please note that square footage refers to planted areas and does not include harsh landscaping.
The law sets the requirements for what should be included in the grading, irrigation and planting plans (the entire ordinance is 41 pages!) But more important is the required calculation of MAWA (Maximum Applied Water Allowance, in gallons per year) and ETWU (Estimated Total Water Use), and ETWU must be less than MAWA. The plant factors for these calculations should be obtained from the WUCOLS document (Water Use Classification of Landscape Species).
Also noteworthy in law: sprinkler irrigation is not allowed in areas less than 8 feet wide. Irrigation clocks should be connected to soil moisture sensors or Et (evapotranspiration) sensors, as well as appropriate rain, frost and wind sensors. Many manufacturers sell subscription services that download weather information to the controller or independent weather sensors that measure solar gain and rainfall on site.