Category Archives: Landscape

Why and How Much To Mulch

Mulch has an underserving bum rap these days. I feel compelled to come to its defense. There is much more than meets the eye about mulch.

Here are the benefits of mulching:

  1. Mulch retains water – Mulching significantly reduces moisture evaporation from the soil. Studies show that a two-inch layer of mulch cuts the water use in a planting area by 20 percent. For California’s climate, especially in the face of the continuing trend of drought, water savings alone is enough a reason to mulch.
  2. It moderates soil temperature extremes and protects plant roots – Mulch insulates and thus alleviates the soil from becoming parched in hot weather. A two-inch layer of mulch can lower the soil temperature of the top four inches of soil about 10 degrees Fahrenheit. And when we experience occasional freezing days in the winter, mulch helps protect the frost-tender plants from damage.
  3. Mulch reduces erosion and mitigates storm water run-off – the bare soil on even very gentle slopes erodes easily from the impact of rainfall that can cause the loss of precious topsoil. The topsoil could also be blown by the wind and carried away. Both the velocity and the volume of run-off water from a mulched site are reduced, resulting in an improved infiltration rate.
  4. Mulching is a very effective weed control measure. In annual beds especially, mulch can reduce weeds by as much as 90 percent. Compared to herbicides, mulching is not only environmentally friendly it also saves labor cost. Laying mulch on the ground or adding mulch periodically can be done just about by anyone, while spraying herbicide must be performed by certified personnel. In addition, herbicide-use needs to be applied more frequently then mulch.
  5. Organic mulch improves the soil structure – its physical characteristics – by enhancing porosity as it works its way into the soil aggregates; mulch prevents soil from crusting and compaction. Organic mulch also supports microbial activities and beneficial organisms that benefit the soil structure.
  6. Organic mulch adds nutrients to the soil as it decomposes and amends the chemical and biological makeup of the soil.
  7. Mulch reduces waste – Plant debris accounts for approximately 7 to 8 percent of what is hauled away to the dump. Landfill volume is reduced by using plant trimmings and chipped wood as mulch.
  8. Uniform sized, textured and colored mulch can enhance the look of a bare site. As wood chips age to a silver gray color, they provide a natural look. Mulch is also used to cover drip irrigation lines and aides maintenance of drip system.

Types of mulch

Mulch can be any material that is spread evenly over the surface of the soil to enhance the growth of plants and appearance. There are two basic types of mulch: organic and inorganic. Inorganic mulch includes materials like rocks and gravel, plastic sheeting, and rubber. Rocks and gravel will absorb heat and warm the soil and so are generally not appropriate for our climate in landscape situations. Plastic sheeting is usually used in controlled vegetable gardens.

Organic mulch used in landscaping can include a multitude of recycled materials:

  1. Chipped or shredded wood wastes from used lumber or wood pallets. These break down very slowly and thus last longer than other types of mulch, but they add little nutrients to the soil. These are best used for pathways.
  2. Wood chips from tree removal or pruning and bark make excellent mulch material. They are usually uniform in size and appearance; and they stay in place and last a medium long period. Rake and replenish at least every other year. Wood chips age to a silvery grey color, but bark tends to keep its color.
  3. Gorilla hair is made from shredded redwood bark and is a tufted and fibrous mulch option. It stays well in place so is suited on slopes. It decomposes slowly and still adds nutrients to the soil. But a thick mat of gorilla hair may prevent rain or irrigation water to seep through and deprive the soil of moisture. A thin layer of no more than 1-1/2-inches of gorilla hair should be used, except at edges.
  4. Mulch made from mixed plant debris is from the above shredded materials plus brush and other plant trimmings. It is finer in texture than pure wood chip or bark. It settles faster and needs to be replenished at least every year or when the thickness is less than 2-3 inches. It can provide a broad range of nutrients as it decomposes into the soil.
  5. Pine needles do not pack down and they resist decomposition. Pine needles do not absorb water like mixed plant mulch but let water trickle through. We do not use pine needles near structures, since dry pine needles can be flammable.
  6. Compost from plant and other organic matter can be used as mulch that provides valuable nutrients and improves soil structure. As it is not effective as weed control, we often add a layer of wood chip on top of compost to suppress weeds.
  7. Leaves are good mulch for providing nutrients and trace elements, so leaves should be left where they fall; leaf drop is nature’s way of returning nutrients and organic matter to the soil. Of course they should be raked away from pavements and from storm drain inlets.
  8. “Grasscycling” is the practice of leaving grass clippings on the lawn as mulch, a good practice that provides nitrogen and other nutrients to the lawn, reducing fertilizer and pesticide runoff. Clippings can also be spread over planted areas and rake it lightly to settle into the soil.

Mulch is usually applied in 2- to 4-inch settled thickness. Fine textured (1/2-inch particle size or less) mulch is generally applied in thin layers to avoid impeding air and water. Most professionals specify at least 3 inches of mulch of any coarse mulch material except on poorly drained soils.

This article first appeared in the November 9, 2016 issue of the Rossmoor News, author Changlin Dillingham.

Those Nasty Leaf Blowers

Hate the leaf blowers? You’re not alone. Many California towns and cities have banned these noisy, polluting machines.

Carmel was the first, in 1975. Now, more than 100 California cities and 400 other cities, towns and municipalities nationwide have banned or restricted leaf blowers. The California EPA, the American Lung Association and the World Health Organization are among the many groups that condemn the use of leaf blowers because the extreme noise and air pollution caused by these machines are hazardous to human health.

Hundreds of cities have returned to the traditional rake and broom, with bags and trash containers, easily banishing this horrible machine from its neighborhoods. Few inventions in human history are as obnoxious as the leaf blower.

How it Started

It all started with a machine for blowing pesticides onto fruit trees in Japan. By simply removing the pesticide canister, this machine became a tool for chasing garden debris. It wasn’t long before American manufacturers spotted an opportunity. The new American blowers were first hailed as an environmental boon when Los Angeles municipal workers began using them in place of the traditional thumb stream from a hose to clean sidewalks and driveways.

The new blowers consisted of a simple two-stroke engine that burned a mixture of gas and oil. Their incomplete combustion and lack of any noise muffler made these machines dirty and loud. Carbon monoxide, nitrous oxides and carcinogenic hydrocarbons spewed from the machines’ nozzles into the air.

A later, cleaner alternative was a four-stroke engine which failed to sell because it was more expensive and less powerful. But people loved the cheap, powerful blower and soon everyone had to have one.

Homeowners, landscapers and their armies of workers fanned out all over the country, spewing strong pollutants and kicking up noxious mixtures of dirt from the ground.

With a muzzle velocity of 150 miles per hour (a wind speed matched only by a hurricane or a tornado), one leaf blower generates as much pollution in one hour as a car driven for 100 miles, according to the Los Angeles chapter of the American Lung Association.

What’s Left After the Leaves Are Blown Away

An airborne mixture of fine particles from unburned fuel, fungi, molds and pollens, pulverized bugs and animal feces hangs in the air for up to four days. The California Air Resources Board reported that fine particles in the air result in 9,000 premature deaths a year in California. At-risk groups include the elderly with cardio-pulmonary problems, people who exercise outdoors, and infants.

Even many landscape professionals agree that stripping a garden of its natural layer of mulch is bad for the plants, diminishing their natural beauty and increasing the need for water, a scarce resource in California. The blowers blast the ground clear of leaf litter, a material that’s beneficial for the soil. In 1990, the city of Claremont stopped using blowers in the maintenance of city property without a net increase in labor hours.

Leaf blower noise is uniquely irritating. For landscape workers, the hazards can be life threatening. The sound from one leaf blower measures 70 to 75 decibels at 50 feet and can reach 90 to 100 decibels at the operator’s ear, according to the World Health Organization. A person inside can be exposed to 100 decibels of noise even with closed windows. Excessive noise is associated with increased blood pressure, headaches, ringing ears, loss of sleep and a lower tolerance for frustration.

Leaf blowers emit compounds that react with sunlight to create ground-level ozone, a key component of smog that can cause respiratory problems. New evidence shows that a relationship between short-term exposure to ozone and mortality in older adults has been mounting, especially among people who are active outdoors.

New findings demonstrate that the road dust that the blowers kick up into the air can remain for days. It’s a toxic mix of endotoxins, mold, and organic carbon compounds. Leaf blowing is not private conduct, because when someone kicks up dust, he extends risk beyond his property line. In some communities, neighbors have to hear multiple blowers at one location.

What Can We Do?

What can homeowners do to protect their own and their community’s health? They can learn what other communities have accomplished and pressure their local governments to take action. They can learn how and where their local government manages its yard waste. They can investigate simple alternatives like hand-powered lawn sweepers that have an attached catch basin. These take even less energy than the rake-and-broom method, but are equally effective. They are quiet and pollution free. Most can be used on both concrete and grass. Leaves can be moved almost as quickly with a rake, lifting less dust into the air.

What can local governments do? They can defend and protect a citizen’s right to quiet enjoyment of their property, especially in the summer and early fall. They can defend a person’s right to protect his or her ears and mental health. And broadly defined, they can do their essential job of defining and enforcing property rights. They can and should ensure that disposal of all kinds of yard waste be sustainably managed, not burned or left to rot and release methane, a potent greenhouse gas.

A good example is the city of Seattle. Homeowners collect yard waste in dedicated bins owned by the city. Trucks take it to sites where it is properly managed. The city then sells the resulting mulch to anyone who wants it at a low price. People can do this. They can banish leaf blowers and return their neighborhoods to normal.

Further Reading and Resources

For the best source of information on this subject, Google References on the Adverse Health Effects of Leaf Blowers 23 April 2014. For California Cities with bans,  For a comprehensive list of cities with bans:  For Information on Leaf Blowers

This article first appeared in the Rossmoor News on October 21, 2015, author, Susan Clark.

California’s Model Water Efficient Landscape Ordinance (M-WELO)

What is M-WELO?

In 1990, during the second driest period in California’s recorded climate history up to that time, California’s legislature passed the Water Conservation in Landscaping Act requiring the Department of Water Resources to adopt a Model Water Efficient Landscape Ordinance (M-WELO).

In 1993, the Department of Water Resources adopted the M-WELO, updating it in 2009, and, again this past July ( July of 2015) in response to the California governor’s drought executive order. Cities are required to implement and enforce the M-WELO, or an equally efficient Water Efficient Landscape Ordinance (WELO). Walnut Creek implemented its WELO in 2012 ( depts/cd/planning/landscaping.asp).

Our own Golden Rain Foundation board of directors effectively used this WELO to coordinate GRF and Mutual landscaping in GRF policies ENV-3.1 and ENV-3.2 (seek to reduce landscape water demand) and GRF/Mutual policies HMU-2.1 through HMU-2.6. Now Walnut Creek must update its WELO by Dec. 31, 2015 to comply with the updated M-WELO, or the M-WELO shall take precedence, according to Julie Saare-Edmonds of the Department of Water Resources.

Updated M-WELO

The updated M-WELO aims to enhance environmental and aesthetic values provided by landscape, but curbs landscape water demand. It minimizes the amount of area planted with lawn, requires more area for low water using plants (including California natives), maximizes irrigation efficiency by requiring highly efficient drip technology where appropriate and prohibits wasteful runoff.

The bulk of the M-WELO applies to new construction and landscape renovation projects tied to permits. New construction in Walnut Creek with landscape areas of 500 square feet or greater must comply with the M-WELO. The M-WELO does not require any alteration of the configuration of existing landscape.

The M-WELO also requires cities to prevent water waste in all existing landscapes: “No property owner or tenant shall permit runoff from an irrigated landscape area due to excessive irrigation run times, low head drainage, overspray, or other similar conditions where water flows onto an adjacent property, walkways, roadways, parking lots, structures, or other non-permeable surface….” No one is exempt, according to Andy Smith of the Walnut Creek Planning and Zoning Department. Smith also acknowledges that, although waste prevention is mandatory, funding limitations make it unenforceable in practical terms. Therefore, compliance with the M-WELO’s rules for existing landscape largely depends upon the motivation of managing agencies. Where willingness and capability are present we can expect water efficient landscape initiatives.

How M-WELO Impacts Rossmoor

We see some of this very positively in Rossmoor through MOD’s turf removal activities and the installation of smart irrigation control technology. We also see this initiative in the Mutual 8 drought tolerant landscape project that introduced drip irrigation, the most efficient irrigation technology commercially available. These and additional actions are examples of very positive ways for any community to achieve the goal of water efficient landscape.

The M-WELO mandates rethinking of landscape and irrigation system design and conformance with new water efficient criteria by prohibiting the placement of sprinklers within two feet of hardscape. If planted, the two-foot setback must use drip irrigation; otherwise it can be covered with mulch, gravel, stone, etc. The M-WELO also requires areas less than10 feet wide to be “irrigated with subsurface (drip) or other means that produces no runoff.” These solutions will eliminate runoff and overspray waste.

Hydrozoning: Zone Planting

Another design solution involves hydrozoning. This means that plants with similar water need and microclimate placement get zoned together according to irrigation requirement, and separately from others with different water need and microclimate placement. Hydrozoning makes it possible to irrigate plant groupings much more efficiently.

For example, median space between parallel roadways frequently includes high water-using lawn with very low water -using tree species. The M-WELO prohibits planting high and low water users in the same hydrozone, an ineffective grouping for water conservation. In addition, the M-WELO prohibits placing high water-using plants, including lawns, in medians. Replacing the median lawn with native shrubs and groundcovers that have water needs more closely matched to that of the trees is just one of several preferable solutions.

It’s all very well and good to do the right thing, but what about costs? The city of Santa Monica and Metropolitan Water District answer this question with their “side by side” demonstration project that employs M-WELO guidelines. Their nine-year study (2004-2013) documented resource consumption of two next-door gardens, a native garden and a traditional garden. The native garden used 83 percent less water, produced 56 percent less green waste and required 68 percent less maintenance than the traditional garden.

This example illustrates the long-term cost saving potential through a greater use of the M-WELO guidelines. The results also created a more water efficient and sustainable future for Community landscapes. (Internet search:

This post first appeared in the Rossmoor News, October 7, 2015, author Tom Stewart.

Why Use Native Plants?

Native plants are now in vogue in California, but not necessarily for all the reasons they should be. Our state’s severe, four-year drought is largely responsible for all the attention natives are now receiving. That is because, once established, natives generally need far less water than many of the plants historically used by landscaping companies and many landscape designers. So using natives not only can save lots of water, but also lots of money.

Native plants are indigenous to our state. They evolved here over time, adapting to the local climate, and still occur naturally in our remaining wild areas. Most of the common landscaping plants in this region are from other parts of the world. They evolved in different ecosystems with different soil organisms, different beetles, butterflies, birds, lizards and other wildlife. Many plants in this region, but certainly not all, require moderate to high amounts of water to thrive. A few examples of such plants here include azaleas, rhododendrons, redwoods, Japanese maples, red maples, purple leaf plum and, of course, grass.

Why does any of this matter? First, it helps to remember that our climate in central Contra Costa County is naturally semi-arid, similar to that of the Mediterranean, with long hot dry summers. The only precipitation comes during the winter, and lately we’ve been getting minimal winter rain. Native plants are adapted to this weather regimen, which is why they tend to need less water.

But there are a number of other reasons to favor native plants over non-natives, and most people are not aware of them. The first one was alluded to above. Native plants support the local ecology, which continues to be destroyed due to human activities. Consider how much of our natural areas have been lost to development, or damaged by oil spills, extracting and burning fossil fuels, using nitrogen fertilizers, and invasive species.

Restoration Gardening

While creating new landscapes using native plants can never replace lost natural habitats, they can help provide an important “bridge” to nearby remaining wild areas. And because this part of central Contra Costa County lies adjacent to these areas, how we choose to re-landscape areas where grass is being removed is likely to make a difference. However, no one is advocating removing any established non-native plants here or in people’s private gardens. But the more native plants that we add to our landscaped areas, the more we will be helping all wildlife survive despite their diminishing and fragmented habitat. This is particularly true if we create plant groupings that contain sufficient numbers of individual species so they can be found more easily by insects and birds.

This landscaping practice is sometimes referred to as restoration gardening. It is one that everyone who cares about our environment can support. The best scientific analysis I have found on why and how native plants sustain wildlife and promote healthy ecosystems is found in a book written by Douglas W. Tallamy titled, “Bringing Nature Home: How You Can Sustain Wildlife With Native Plants.” Two books written by Judith Larner Lowry describe why and how to create sustainable landscapes and are also recommended reading. They include “Gardening With a Wild Heart: Restoring California’s Native Landscapes at Home” and “The Landscaping Ideas of Jays: A Natural History of the Backyard Restoration Garden.”

In addition to saving water and money, and supporting the local ecology, California native plants offer some additional benefits in landscaped areas. Their use can make a site look more relaxing because it reminds us of natural areas, but only if the garden is designed with an informal rather than a manicured “look.” California natives require comparatively little pruning and little to no fertilizer. They require even less water when fallen or removed debris (leaves, small twigs, etc.) is left in place or spread out as natural mulch, rather than being collected and removed. Native plants also usually require no pesticides because they have developed their own defenses against many pests and diseases. Avoiding pesticide use prevents killing beneficial insects and keeps toxins out of our waterways. All of these practices could reduce the time hired landscaping personnel and homeowners spend maintaining gardens.

Finally, readers may be interested in the position of California legislators on the drought and the use of California native plants. In July 2015 they approved a revised “California Model Water Efficient Landscape Ordinance.” It aims to increase water use efficiency, in part by limiting the percentage of landscapes that can be planted with high-water-use plants. The ordinance specifically mentions the “protection and preservation of native species and natural vegetation;” the “selection of water-conserving plants, trees, and turf species, especially local native plants;” and the “selection of plants based on local climate suitability.”

Increasing the use of native plants in our landscapes is something we can easily do if we plan carefully. It will help us save water, and can have the added benefit of improving the health of our local ecosystem. I encourage everyone to become involved in this effort.

This article first appeared in the Rossmoor News on September 02, 2015. Author: Bob Hass. Editor’s Note: the California Native Plant offers an excellent list of native plants specific to Walnut Creek.

Why Artificial Grass Is Bad for the Earth

Artificial turf is bad for people, for animals and for the earth.

Rossmoor was smart in limiting the use of artificial turf to our dog park. The plan was well researched; it has complete shade, was properly installed and is cleaned regularly with appropriate compounds. And users get their paws washed after a visit. Unfortunately, many Californians now regret their uninformed decisions to replace real lawn with fake — assuming it would save water as well as maintenance time and money.

Members of the Rossmoor Water Conservation Committee were encouraged to testify when EBMUD voted last month on whether to offer a rebate for users who replaced real grass with fake grass. So we did some research and learned a lot from experts there.

Why is Artificial Grass Harmful?

Artificial turf retains heat. Temperatures reach nearly 200 degrees F both above and below it [“Synthetic Surface Heat Studies” Brigham Young University, 2002]. Typically, pets and barefoot children cannot tolerate walking on it on warm, let alone hot days. It creates a “heat island” effect, which holds in heat during the day and releases it at night – not what we need during a drought.

Underneath, it kills healthy soil bacteria, worms and root systems. It must be watered regularly to keep it cool — water that can be better used to maintain any of several types of drought-resistant sod (if a playing surface is needed) or lush drought-resistant planting. It also requires water to wash it, and is far from maintenance-free. Herbicides (like Roundup) and fungicides are included in the washing — both are bad for the water table below. Real lawn or plants absorb carbon dioxide from the air and release oxygen. Artificial turf doesn’t, and sadly it diminishes the incentive to learn healthy drought-sensitive planting, mulching and irrigating.

Another serious drawback is its expense; current prices range from $8 to $15 per square foot. It can easily cost $5,000 to cover a small yard and over $100,000 for an athletic field. The cost includes preparing the ground and using specific layers of padding underneath to help drainage. The older forms of artificial turf were made of various synthetic ingredients, including crumbled old tires. These are considered more toxic for reasons I’ll include below, but they are still on the market, and are typically sold more cheaply – attracting cost-conscious buyers.

It’s Toxic Too

The toxins in artificial turf threaten our health via contact, consumption (via water), and inhalation. All these routes expose humans and other living things to acetone, arsenic, benzene, chromium, halogenated flame retardants, lead, mercury, dioxin, carbon black, styrene and Butadiene. These chemicals have been proven to cause cancer and other diseases. As the turf degrades over time, larger quantities of chemicals are released.

When worn-out synthetic turf is replaced, the old pieces will likely end up in landfills, and that can lead to toxic water runoff. Plants and organisms that absorb contaminated water often increase its concentration – a special concern if eaten by humans or other animals. The EPA strictly regulates the disposal of rubber tires; however, there is no regulation of the disposal of artificial turf containing crumbled tires. The newer, more expensive forms of turf have replaced the bits of tires with materials that are untested.

The turf is a reservoir for not only fungus and bacteria, but also contaminated organic matter. It lacks the normal biocycles in nature that reduce the hazards of this exposure. Serious skin abrasions and infections (including MRSA — antibiotic resistant “super bugs”) are among the reasons the women’s soccer league recently took legal action to avoid playing on it.[NIH 2011, CDC 2013].

As the turf becomes warmer, the amount of its “off-gassing” increases; this is code for toxic fumes. There are measurable short term ill effects from this; long-term side effects have not been studied — often a concern to neighbors. The industry knows about the risk of high heat – that’s why their turf is impregnated with flame retardants. The effects of drinking, eating (via plants raised with toxic water) and regularly inhaling this flame retardant have not been studied.

The seven EMBUD directors found it easy to “just say NO” (their words) to the proposed rebate for artificial turf. However, the use of artificial turf is increasing. Many cities and counties are considering lifting previous bans on its use. Governor Jerry Brown, who was previously opposed, has recently said that he’d “now consider it due to the drought.” We need to contact these elected officials. A list of their emails and phone numbers is available on request.

This article originally appeared in the Rossmoor News, August 02, 2015. Authored by Carol Weed, M.D.