When Watering Must be Cut Back

There will be times when California will be in a drought and mandatory water use restrictions will be put in place. Consider the following...

Reduce Irrigation Amount and Modify Watering Schedules

Landscapes and lawns are commonly over-watered. When watering must be reduced for a season or longer, it is wise to prioritize which plants will receive the limited water that will be available.  Focus water on plants and plantings that are of highest value and most difficult to replace (like trees), letting low value, easier to replace plants and plantings go with much less or no water. Thus, prioritize water on trees, shrubs, groundcovers, and vines, and severely reduce or eliminate water applied to lawns, annual flowers and other plants that are relatively inexpensive and easy to replace. 

Many non-turf plantings will continue to perform acceptably if the current amount of irrigation they receive is simply reduced 10% to 20%, and if lawns are watered no more than three times per week. Don't forget to adjust irrigation days at least monthly to reflect average changes in weather.

For added water savings, you can reduce your watering by as much as 20-30 percent. The plants may not look great or grow much, but they will survive. Some people over-water so much that when they cut back 20%, they find their landscape actually becomes healthier! Woody landscape plants (trees and shrubs), even those not usually noted as low-water using, possess drought resistance characteristics that can be taken advantage of with this strategy. Many plants will show symptoms of water stress, such as leaf drop, wilting, browning leaves, and yellowish or grayish foliage. Tree and shrub canopies could thin out and lawns will provide only thin, poor looking, minimal soil cover. Expect brown areas to develop in lawns because of inefficiencies in the irrigation system and variations in soil conditions that are masked when water application is greater. Under survival amounts of water, grass will show drought symptoms within a few weeks while many woody plants tend to decline gradually over a period of several weeks or more. True drought resistant plants, regardless of whether they are labeled native plants or California friendly plants, tolerate suboptimal watering for longer periods than other plants.

Photo by Birkholz/iStock / Getty Images

Lawns and landscape plants will recover when watering is restored to required levels, but there could be some permanent loss of branches in woody plants and dead areas in lawns that will require seeding or sodding to restore complete soil cover.  The longer the period water is reduced to survival levels the more likely some permanent plant damage or death will occur.

“Except for drip systems, be sure to schedule irrigation between about midnight and 6:00 AM. Watering during this period minimizes evaporative losses of water and avoids windy conditions that breakup irrigation spray patterns. ”

Sometimes sprinkler or drip systems apply water faster than the soil can absorb it and some of the water runs off. This is especially common on slopes. If runoff occurs before or after an irrigation is complete, divide the total run time needed into 2-4 cycles scheduled at least 30-60 minutes apart so that water applied at each cycle has time to soak in before the next increment is applied. 

Should I Just Shut Off My irrigation?

Frequently, the first reaction to drought, mandated watering restrictions, or increased water costs is to stop all or most landscape and garden irrigation, and eliminate or replace large portions of these plantings. Before you stop irrigating your landscape or remove an entire lawn or landscape planting, consider the following points. 

  • Grass is the only plant material that works very well as a cooling, walk-on or play-on surface. If these functions are needed (like in a backyard), there is no effective substitute.
  • Converting lawns to artificial turf is expensive, and these surfaces become very hot in the sun. Also, consider that artificial turf requires periodic maintenance and sometimes needs to be washed off to remain in good condition. It has a limited life expectancy of about 10 years after which it must be removed, disposed of, and replaced. 

Research has clearly shown that most common trees, shrubs, and groundcovers that are not usually considered water wise are actually very drought resistant once established if cared for and irrigated properly (Remember, water deeply and infrequently). 

Thus, replacing lawns or other landscape plants with so-called drought-tolerant or low-water use plants, may be unnecessary in order to reduce a landscape’s water demands significantly and meet mandated cutbacks.

It is expensive to change over traditional landscapes and lawn areas to new, well-designed and properly installed plant palettes. Low-density plantings and new irrigation systems along with extensive zones of mulch incur significant costs for labor, plant material, mulch, installing or retrofitting irrigation systems, professional design fees, and other items. 

While shutting off or terminating irrigation and removing plantings can reduce water demand, there are significant costs to consider before doing this (See Table 2). The most obvious and most significant cost is the loss of the amenities and benefits urban plantings provide such as: oxygen, carbon sequestration, rain capture, dust and erosion control, shade which promotes energy savings, wildlife habitat, food, beauty, recreation, enhanced property values, psychological well-being, and cultural or historic value. Increased heating of air, soil, buildings, and other surfaces along with more dust and erosion are usually noticed quickly.  Lawns are very effective in erosion and dust control, environmental cooling, and glare reduction, but they are often opposed because of their relatively high water demand. 

  TABLE 2.  Benefits and costs to consider before removing or reducing landscape plantings

TABLE 2. Benefits and costs to consider before removing or reducing landscape plantings

Terminating landscape irrigation or removing lawns and landscape plantings is not necessary to reduce landscape irrigation significantly because existing landscapes often perform acceptably with much less water than they are commonly given. Abruptly terminating irrigation can lead to stress and possibly death of turf, trees, shrubs, and other plants, particularly if watering is stopped for several weeks or more in summer. Trees within the lawn are solely dependent on lawn irrigation to meet their water needs, so they will suffer, decline, and even possibly die over time if water is turned off to lawns. Declining and dead trees can become hazardous because they might drop large limbs or the trunk might fail, potentially causing serious damage to life and property. If one waters just for the needs of trees that have lawns around them, the grass will likely survive but be of very poor quality.

Here are some helpful publications from the University of California (Provided with Permission):