Keeping Landscape Plantings Alive under Drought or Water Restrictions

Janet Hartin and Ben Faber

University of California Cooperative Extension

 

BY JANET HARTIN Plants that do not receive enough water due to drought or governmental restrictions aimed at water conservation eventually show signs of water stress. Although plants vary in the amount of water they require for optimal growth and development, most exhibit characteristic symptoms when they are in need of water. Because water-stressed plants need to be watered at an early stage of water deficit to prevent irreversible damage, it is crucial to check plants regularly for symptoms of drought, preferably during the afternoon when symptoms are most evident.

Common symptoms include: - wilting or drooping leaves that do not return to normal by evening - curled or chlorotic (yellow) leaves that may fold or drop, or foliage that becomes grayish and loses its green luster - new leaves that are smaller than normal - lawn grasses that retain a footprint for several minutes Below are suggested methods to maintain various landscape plants during water restrictions and severe drought.

Ornamental Trees. Most homeowners wisely choose to use whatever water is available to save their mature landscape ornamentals and fruit trees. One or two deep irrigations with a garden hose several weeks apart in spring and summer will often keep these valued plants alive through summer, especially if roots are relatively deep. Although mature trees can often survive one season with only one or two deep waterings during the spring and summer, two seasons without enough water can result in severe drought stress and even death. Drought-stressed trees can be more prone to damage from diseases and insects.

Fruit and Nut Trees. Keeping fruit and nut trees alive during severe water shortages is also possible, although crop production will probably be greatly reduced or stop. To produce a good crop, deciduous fruit and nut trees need adequate water in their root zones continuously from bloom until harvest. Citrus trees need adequate soil moisture during spring to set fruit and steady water in summer and fall to produce acceptable size, numbers, and quality of fruit. However, fruit and nut trees can be kept alive with a few early-season water applications, but they may not set much fruit.

Vegetables. Vegetables are difficult to maintain during a drought. Know the critical watering periods for vegetables and you can target the timing and amount of water to add. As a rule of thumb, water is most critical during the first few weeks of development, immediately after transplanting, and during flowering and fruit production. Tomatoes, beans, and root crops such as carrots require regular watering and are not tolerant to long, dry periods. Viney vegetables such as squash and zucchini often fare better and can be kept alive with a few waterings once or twice a week through the season.

Shrubs. Most established shrubs can survive long periods of dry soil. Thorough spring watering and one or two thorough waterings in the summer keeps most well-established shrubs alive for at least one season.

Ground covers. Ground covers often survive on about half the amount of water they would receive under optimal conditions, although some dieback may occur. To avoid serious drought stress, they should be watered at least every 3 to 6 weeks from April through September, depending on location and soil conditions.

Lawns. Warm-season lawns planted in bermudagrass and buffalograss are more drought-efficient than cool season grasses (e.g. tall fescue and ryegrass) and may come back after several weeks of dryness. Cool season grasses may die within a month or two of receiving no water. Signs of drought include wilted leaves and a blush-gray appearance followed by yellow leaves that will eventually turn brown. Cutting the length of irrigation down to ½ of that recommended in the UC Lawn Watering Guide http://anrcatalog.ucdavis.edu/pdf/8044.pdf and watering only once or twice a week may help get your lawn through the drought. (Once a lawn stops receiving adequate moisture, it will gradually turn brown and go dormant over time. A lawn that recently turned brown from drought can often be revived with regular, thorough watering.

 

BY JANET HARTIN

Dear UCCE San Bernardino County Master Gardeners,

This has been a busy week! First of all, a huge thanks to the perennial Master Gardeners who shared their volunteer experiences and horticulture expertise with the new class on Saturday in Chino Hills.  It was all valuable and greatly appreciated!

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We are in the process of adding drought-related materials to both the statewide Master Gardener website and to the statewide UC ANR websites. Below is an article on using graywater that I thought you all might be interested in.

 

Use of Graywater in Urban Landscapes

Janet Hartin and Ben Faber

UC Cooperative Extension

Definition and Overview: The use of graywater to irrigate landscape plants is increasing throughout the United States, particularly in California and other arid states. In the United States, ”graywater” most often refers to wastewater that originates from residential clothes washers, bathtubs, showers, and sinks, and it excludes wastewater generated from kitchen sinks, dishwashers, and toilets (black water). In California, under Health and Safety Code § 17922.12, graywater is defined as “untreated wastewater that has not been contaminated by any toilet discharge, has not been affected by infectious, contaminated, or unhealthy bodily wastes, and does not present a threat from contamination by unhealthful processing, manufacturing, or operating wastes.

Graywater includes, but is not limited to, wastewater from bathtubs, showers, bathroom washbasins, clothes washing machines, and laundry tubs, but does not include wastewater from kitchen sinks or dishwashers.” As of August 2009, a permit is no longer required for the installation of the following single-family or two-family residential graywater irrigation systems if other conditions under section 1603A1.1 of the Department of Housing and Community Development (HCD) are met: a simple clothes washing graywater system as long as it does not require cutting of the existing plumbing piping; or, a single-fixture system that collects graywater from one plumbing fixture. All other systems require a construction permit prior to erection, retrofitting, construction and installation as stated in the actual code. The full text of these standards can be viewed at the California Department of Housing and Community Development (HCD) Division of Codes and Standards website, http://www.hcd.ca.gov/codes.

Because these regulations may change at any time, always check with HCD and local enforcement agencies before developing plans for or installing a graywater system. Cities and counties can impose stricter guidelines than the state, so homeowners interested in installing graywater systems should contact their local jurisdiction for specific regulations concerning graywater handling and use.

Laundry-to-landscape graywater systems are relatively simple to install and are inexpensive. The hose exiting the clothes washing machine is attached to a valve that separates graywater from water destined for the sewer. The graywater is diverted through a 1-inch main irrigation line with ½-inch tubing outlets placed throughout the landscape terminating in a valve box set in what is termed a “mulch basin” that surrounds plants being watered (see below). The washing machine pump distributes water directly to the landscape with no filter. A vacuum break or backflow prevention device may also be needed.

Keep in mind that salt-free and boron-free liquid laundry detergents should be used for irrigating the landscape. In addition, chlorine bleach should be avoided. All laundry-to-landscape systems not requiring a permit are required to be equipped to direct flow back to the sewer (e.g., a three-way valve)  have valves and direction of graywater flow clearly labeled supply graywater to landscape plantings only on the homeowner’s property include an operation and maintenance manual discharge graywater underneath a 2-inch cover of mulch, plastic shield, or stone covering.

Systems must not use water contaminated by diapers and human waste;  contain hazardous chemicals from oily rags, photolabs, car pasts, etc.;  create pooling of standing water or an open tub; create water pollution through runoff or deep percolation of graywater into ground and surface waters; include a pump (other than a washing machine internal pump);  connect to any potable water supply; or, affect or alter electrical, plumbing, mechanical, or structural components of the home.

Mulch basins receive and distribute graywater to plant root zones and are constructed by removing several inches of soil and replacing it with coarse organic mulch. These basins are established in bed areas or near plants so that the graywater reaches plant root systems. They need to be sized correctly to prevent surface ponding. Sizing depends mainly on soil texture (sandy loam, clay loam, etc.). Graywater percolates quickly through sandy soil, requiring minimal mulch. In slower-percolating clay loam soil, a larger mulch basin is required around the valve box to prevent graywater pondage. Large wood chip mulch is more durable and longer lasting than smaller wood chip mulches or shredded fiber.

Applying graywater through a drip irrigation system is not generally recommended. Drip emitters can quickly clog with hair and other graywater products and requires a filter and regular filter cleaning. A drip system for this use also requires a backflow preventer to ensure that potable water is not contaminated and a pump and controllers to assure that water flows through the emitters. These systems are expensive and require regular maintenance.

Benefits and Risks: Using graywater to irrigate landscape plants can conserve water and electricity and reduce water bills by recycling water otherwise destined for a wastewater treatment plant. Since an estimated 30 to 50% of home water use produces graywater, significant savings can be realized by reusing this source of nonpotable water to irrigate landscape plants. A typical household (2.6 people) produces an average of 90 gallons of graywater each day. While most graywater systems will not supply enough irrigation water to irrigate an entire traditionally landscaped yard, most can supply one-half to three-quarters of the water required by a drip-irrigated water-efficient landscape with limited or no turf.

The potential risks should be carefully evaluated before deciding whether to install a graywater recycling system. Graywater varies substantially in quality and potential risks from site to site. Many household cleaning products, as well as many shampoos, soaps, and detergents, contain dyes, bleach, chlorine, sodium, boron, and phosphate, which can pose significant human and environmental health concerns and can injure and even kill plants at high dosages over a short period or smaller dosages over a longer period.

Impact of Graywater on Human Health: Because of the recent changes regarding graywater reuse under California and other state statutes, research pertaining to the long-term impacts and risks of graywater reuse on human health, plant health, soil chemistry, and ground and surface water quality is very limited. A review of current research-based information follows. Research examining the microbial constituency of graywater indicates that direct contact with graywater can pose a health risk to humans. Pathogens can enter graywater through food sources in the kitchen, which is why use of graywater generated from kitchen sinks and dishwashers is not recommended. Also, because pathogens can enter graywater through fecal matter, avoid water contaminated by dirty diapers. Pathogens posing the greatest concern in graywater include bacteria such as enterotoxigenic Escherichia coli, Salmonella spp., Shigella spp., Vibrio cholera, Campylobacter spp., and Legionella spp.; protozoans such as Giardia spp. and Cryptosporidium spp.; and viruses such as enteroviruses, hepatitis A, rotavirus, and Norwalk virus.

Graywater should not be applied directly to edible plant parts or root crops. To be safe, it should be applied only to nonedible ornamental plants. Avoid splashing graywater on neighboring edible plants. Graywater should not be applied through sprinkler systems, since droplets containing harmful microbes can become suspended in the air and breathed.

Impact of Graywater on Soil Chemistry and Water Quality: Limited research exists that addresses the fate of microorganisms found in graywater and their impact on indigenous soil microorganisms, soil chemistry, and water quality. Infiltration through soil, rock, and other materials that serve as filters can significantly diminish the threat of water pollution from graywater use. Unfiltered graywater accumulating in surface water and graywater seepage into nearby wells can diminish water quality.

Impact of Graywater on Plant Health: Because graywater is often rich in nutrients required for plant growth, ornamental plants may benefit from its use. However, numerous studies indicate that graywater may contain significant levels of sodium and other salts harmful to plants, particularly from powdered laundry detergents. Since ornamental plants vary dramatically in their sensitivity to potentially harmful salts found in graywater, care must be taken when plants are irrigated with graywater that is high in salts, particularly over a long-term basis.

In general, evergreen trees are more salt sensitive than deciduous trees. Very little is known regarding the impact of graywater use on annual bedding plants.  More research is needed on the impact of graywater on plant health since the chemical composition of graywater is different than that of treated wastewater and surfactants are widely used in household cleaning products.

Regardless of what graywater system is chosen, the following precautions should always be taken:

-Carefully label all valves and pipes associated with your graywater system and prevent backflow.

 -Do not store graywater more than 24 hours. Wear gloves and do not come into direct contact with graywater.

 -Do not let graywater pool or run off of the soil surfacer or come into contact with well water.

-Do not irrigate edibles with groundwater or allow it to splash on neighboring edible plants.

-Do not irrigate turfgrass or ground cover areas with graywater, since potentially harmful microorganisms can remain on the surface.

-Do not use graywater contaminated with human waste, infectious disease organisms, grease, paint residue, gasoline, solvents, or other chemicals found in household and industrial products.

-Keep the graywater system simple and avoid systems requiring heavy upkeep and maintenance. Contact a professional with experience designing and installing graywater systems if you lack the specific knowledge or time to undertake the project yourself.

Bibliography

Roesner, L, Y. Qian, M. Criswell, M. Stromberger, and S. Klein. 2006. Final report: Long-term effects of landscape irrigation using graywater: Literature review and synthesis. Alexandria, VA: Water Environment Research Foundation. WREF website, http://www.urbanwater.colostate.edu/A1_Published_Report_03CTS18CO.pdf

State of California Graywater Code. 2012:http://www.hcd.ca.gov/codes/shl/Preface_ET_Emergency_Graywater.pdf

Wu, L., and L. Dodge. 2005. Landscape plant salt tolerance guide for recycled water irrigation. Slosson Research Endowment for Ornamental Horticulture, University of California, Davis, Department of Plant Sciences website, http://slosson.ucdavis.edu/files/66355.pdf.

BY JANET HARTIN -

Dear UCCE San Bernardino County Master Gardeners,

Due to our severe drought, I will be updating our MG website’s water conservation information often. Below is an overview of some of this information:

There is more interest than ever in beautiful water-efficient landscapes due to drought and a desire to conserve a precious resource. Because about one-third of a typical Southern California family water use is directed at outdoor irrigation - about 200 gallons a day - significant savings can be realized through efficient irrigation.

The good news is that many of the recommendations do not entail large overhauls or expensive fixes. In fact, you do not need to tear out your current landscape, contrary to popular belief. While native gardens are generally water-efficient and low-maintenance, there are several non-native plants that thrive in Southern California, as well, and are just as drought efficient. And, diversifying a plant palette is always a good idea and results in fewer pest problems and a more interesting, aesthetically appealing landscape.

Here are some tips to help you conserve water and beautify your landscape: Don’t overwater! Overwatering landscape plants is more common than under-watering. True, newly planted ornamentals and garden plants require frequent light irrigations due to their immature, smaller root systems. But established plants do much better with deep and infrequent irrigation. They do not need to be watered everyday and actually prefer to be irrigated deeply and infrequently. Most perform best on two or three deep penetrating irrigations per week. Know how much water to apply.

Become familiar with scheduling irrigations based on Sunset Zones, which encompass smaller geographical areas than do the larger USDA zones. Within San Bernardino County alone, there are several distinct Sunset zones taking into account inland, desert and mountain climates as listed below:

Sunset Zones for Various San Bernardino County Cities:

San Bernardino, Chino, Ontario, Redlands and other inland cities: 18

Barstow, 29 Palms, Yucca Valley: 11

Victorville,Hesperia: 10

Needles: 13

Big Bear: 2B

Higher Elevation of San Bernardino Mountains: 3A

• Plants vary in their water requirements and while no single plant list is exhaustive, there are several that will get you in the ballpark. You can consult a reputable online resource such as the Sunset Plant Finder website, http://plantfinder.sunset.com, which allows multiple criteria to be entered during a plant search or the updated Water Use Classification of Landscape Species WUCOLS) database, http://ucanr.org/sites/wucols.

• Place plants with similar water needs together so they can be irrigated on the same schedule and valve. Become familiar with microclimates within your landscape. These are distinct areas that vary in temperature, sun exposure, wind, humidity, and soil conditions. All these factors play a large role in which plants will thrive and which ones will suffer.

A vivid example to illustrate this point is comparing the water requirements of a tree planted in the middle of a ‘heat island’ created by a large area of parking lot asphalt to that of the same tree species growing in a park surrounded by greenery. In the summer, the tree growing in the parking lot requires 20 - 40 percent more water due to reradiated heat and higher temperatures.

While your landscape may not have such drastic variations, there are substantial differences on north and south-facing slopes and in shady versus sunny areas.

• Know when to water. Get your hands dirty! Use a shovel or trowel to dig a small hole six to eight inches deep in your garden soil, being careful not to disturb plant roots. Soil that is wet enough but not too wet will feel like a well wrung-out sponge. If the soil falls apart easily, it’s a little too dry and you should irrigate. If a lot of water oozes out, wait a few days before you water.

• Know your soil type (texture). This goes hand-in-hand with knowing when to water. Sandy soil holds less water but drains much faster than heavier clay soil. Therefore, plants growing in it need to be irrigated more often. Sandy soils take in water and drain much faster, as well, which can lead to water and nutrient loss (and pollution) below the root zone. Clay soils, on the other hand, take in water much slower and are more likely to incur run-off from the soil surface, which also can result in water pollution and wasted water. An easy way to determine what type of soil you have is to do the ‘feel test’. Soil containing clay will form a ribbon as you squeeze it between your thumb and forefinger while sandy soil will crumble and not ribbon.

• Add composted green waste to your soil, mixing it in evenly six inches to one foot deep. Compost increases the water-holding capacity of sandy soils and the drainage rate of clay soils, making both more manageable and less prone to water waste. As we discussed last week, compost makes a great soil amendment for small woody ornamentals and garden plants, but should not be used in tree planting sites. This is because tree roots will tend to stay in the amended soil rather than venture out into poorer quality soil, resulting in small root systems unable to support the maturing tree.

• Apply three inches of mulch on the top of soil around your landscape and garden plants. Be sure to keep it at least one foot away from tree trunks to avoid wet crowns subject to disease-forming pathogens.

• Irrigate ornamentals and vegetables with a drip system. This will save water by applying moisture directly into the root zone of plants, which minimizes evaporation of water off the soil surface between plants. Drip systems are not difficult to install; most home supply stores and irrigation supply companies offer free guidelines detailing their installation. If you don’t have the time or feel competent to do the installation yourself, there are many reasonably-priced landscapers/irrigation specialists who provide this service.

• Consider downsizing your lawn area to what you actually use and enjoy. When irrigated effectively, warm-season grass such as Bermuda grass is relatively drought-efficient. It’s not the grass that wastes the water, but aging, inefficient irrigation systems that apply water unevenly across the lawn.

• If you do keep your turf, water it efficiently. The University of California Lawn Watering Guide http://anrcatalog.ucdavis.edu/Items/8044.aspx lists the number of minutes per week to water your warm or cool-season lawn year-around based on its water use rate seasonally and how much water your system puts out. It explains step by step how to conduct a ‘can test’ to determine the system’s output rate and evenness of application and lists tips to improve the distribution uniformity for the system. Using this guide generally reduces water waste between 20-50% which will save you money and improve the health of your lawn.

• Consider installing a ‘smart’ irrigation controller that applies water based on plant water needs and may be hooked up to a weather-based network. Instead of simply relying on a timer that may be set arbitrarily on no particular schedule, “smart” irrigation controllers rely on weather, site and soil moisture for determining irrigation schedules.

• Learn to recognize plant drought symptoms. Turf will hold a footprint and tree and shrub leaves lose their luster and may shrivel or turn light brown when dry.

• Water early in the morning to reduce water waste from soil evaporation. • Check your irrigation system, faucets, and hoses regularly and repair leaks and broken parts.

• Use a broom rather than a hose to clean patios, driveways and walkways.

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Know the critical watering periods for vegetables and you can target the timing and amount of water to add. As a rule of thumb, water is most critical during the first few weeks of development, immediately after transplanting, and during flowering and fruit production. The critical watering periods for selected vegetables follow:

(The following information was adapted from Colorado State University and Trinity County Master Gardeners, CA)

• Asparagus - Spear production, fern development. • Cole crops: broccoli, cabbage, and cauliflower - The quality of cole crops is significantly reduced if the plants get dry anytime during the growing season. Water use is highest and most critical during head development.

• Beans - Beans have the highest water use of any common garden vegetable, using ¼ to over ½ inch of water per day (depending on temperature and wind). Blossoms drop with inadequate moisture levels and pods fail to fill. On warm, windy days, blossom drop is common. For the observant gardener, a subtle change in plant color indicates a need for irrigation. When moisture levels are adequate the bean plant is a bright, dark grass green. As plants experience water stress, leaves take on a slight grayish cast. Water is needed at this point to prevent blossom drop.

• Carrot and other root crops - For quality produce, these crops require a constant supply of moisture. They are intolerant of dry soils. Cracking, knobby and hot flavor root crops are symptoms of water stress.

• Corn - Water demand for sweet corn is most critical during tasseling, silking, and ear development. Yield is directly related to quantities of water, nitrogen and spacing. Water stress delays the silking period, but not tasseling. Under mild water stress the crop may tassel and shed pollen before silks are ready for pollination. The lack of pollination may reduce yields or even eliminate ear production.

• Lettuce and other leaf vegetables - Water demand is most critical during head (leaf) development. For quality produce these crops require a constant supply of moisture. They are intolerant of dry soils. • Onion family – Members of the onion family have an inefficient rooting system making irrigation management a key factor in produce quality. They require a constant supply of moisture and are intolerant of dry soils.

• Peas - Water demand is most critical during pod filling

• Potatoes - If potatoes become overly dry during tuber development, tubers will be knobby.

• Tomato family: tomatoes, peppers and eggplant -- Water demand is most critical during flowering and fruiting. Blossom-end-rot (a black sunken area on the bottom of the fruit) is a symptom of too much or too little water. The tomato family has a lower water requirement than many vegetables and plants are often over-watered in the typical home garden.

• Vine crops: cucumbers, summer and winter squash, and assorted melons - Water demand is most critical during flowering and fruiting. Vine crops use less water than many vegetables and are often over-watered in the typical home garden.

============END OF DROUGHT INFORMATION=============

Our UC ANR VP, Barbara Allen-Diaz, was interviewed by USA Today about Earth Day activities that will be conducted by MGs throughout the state. Several San Bernardino County Earth Day events will be included thanks to Dona Jenkins' quick response to the request (there was less than one day to respond)! Ten counties responded.  The stories were compiled and sent along to Barbara for her interview. Melissa Womack will post it to the statewide MG Facebook page ‘UC Master Gardener Program.’  Thanks Dona!

Have a great week!

Janet

BY JANET HARTIN -

Dear UCCE San Bernardino County Master Gardeners,

There is more and more research connecting spending time in nature with stress reduction and improved mental health. Here is just a small sample:

- A study published in Landscape and Urban Planning found lower levels of cortisol (a stress hormone) and lower levels of self-reported stress in adults living in proximity to green spaces, parks, and other natural settings compared to those living in city environments. Not surprisingly, residents living nearer these natural settings also reported spending more time in open green spaces compared to their city dweller counterparts. Lead researcher Catharine Ward Thompson (director of OPENspace Research Centre at the University of Edinburgh) links the relationship of access to exercise and breathing fresh air to living in greener environments and, hence, better health.

-Amazingly, according to a 2010 study in the journal Environmental Science & Technology as little as 5-10 minutes of light outdoor exercise such as walking can significantly improve one’s self-esteem and mood, as well.

-A new study published in the same journal examined data from over 1,000 participants who either moved to open space, greener urban areas or less open, city environments. Researchers found that, on average, those moving to greener, less urban areas realized a nearly immediate mental health boost sustained for three years or longer post-move. Those moving to more built-up environments realized a reduction in their mental health which interestingly occurred before they moved!

What’s the take-home message? As University of California Master Gardeners, promote the association between outdoor activities such as gardening and improved health whenever possible! Participate in an upcoming Sustainable and Edible Landscape Workshops our program is offering throughout the county or serve as the Master Gardener representative on your Healthy Community committee or help get one started if there isn’t one in your community.

Why is it Important? San Bernardino County is the largest county in the contiguous United States with a population of two million living in diverse geographic and civic environments. The health problems facing this region make it imperative that we give priority to the health needs of our residents. Current statistics for the County of San Bernardino include: - Fourth most obese region in the United States with two out of three residents considered overweight or obese - Third highest heart disease rate in the state - 71% of school children do not meet the fitness standards - Worst healthy food access in state, with six times as many unhealthy food retail outlets as healthy - Two thirds of adults are not meeting recommended physical activity levels.

In 2006, the Healthy Communities program was created as a central point of contact for health related issues throughout the county. It provides technical assistance to communities throughout the county giving specific recommendations for policy and environmental strategies to improve residents’ health. Partners collaborate on multiple projects throughout the region.

Currently, Healthy Communities partners with these cities: Adelanto, Ontario Apple Valley, Rancho Cucamonga, Chino, Redlands, Chino Hills, Rialto, Colton, San Bernardino, Fontana, Upland, Hesperia, Victorville, Montclair, and Yucaipa.

Contact Information for San Bernardino County Healthy Communities Program: Bobbie Luna, Cell: (909) 677-8339 Email: Bobbie.Luna@dph.sbcounty.gov.  

(Please email MG Expansion Coordinator Dona at djenkins@ucanr.edu if you are interested in working with a specific city so she can record your interest and let you know of other MGs of like mind.)

Have a healthy week!

Janet