We tend to think of gardens and yards as healthy places where we can enjoy nature. But the truth is, many conventional gardening and landscaping practices aren't all that healthy or natural. They typically involve a lot of irrigation water as well as chemical fertilizers, herbicides and pesticides. They also produce a lot of plant waste from pruning and use a lot of fossil fuels for mowing and trimming.
What's more, invasive plants used in landscaping often escape into natural areas, where they can spread rapidly, crowd out native plants, degrade wildlife habitat, and increase the wildfire fuel load.
Whether you are planning a major landscaping project or just planting a few beds, these recommended practices will help ensure your property looks beautiful and does a world of good.
Before replanting an area of your yard or garden, have the soil quality tested. You can send soil samples to a soil lab that will analyze it for texture, nutrients, organic matter content and pH. If the lab advises soil amendments, ask for their recommendations for organic or environmentally friendly amendments.
Choose plants that require little or no summer water and that are appropriate for your site's soil and microclimates. In general, these will be California natives and Mediterranean species. Plant a variety of trees, shrubs and other perennials, limit annuals, and don't plant invasives. See the California Invasive Plant Council website at www.Cal-IPC.org for a list of species considered invasive in your area.
Give plants plenty of room to mature. This will result in healthy plants and reduce the need for pruning and shearing.
Fire-safe landscaping techniques
California's long dry season makes fire protection an important consideration for landscape design. The following landscaping design practices can help defend your home by reducing fuel accumulation and interrupting a fire's path.
- Determine whether your property is in a high-risk area. Map the site, identifying exposure to prevailing winds during the dry season and steep slopes that can increase wind speed and convey heat. Identify adjacent wildlands or open space, as well as south- and west-facing slopes and their vegetation, particularly species that burn readily.
- Create defensible space. For sites adjacent to fire-sensitive open space or wildlands, create defensible space around buildings; this is an area where vegetation is modified to reduce the fuel load and allow firefighters to operate. Use irrigated, low-growing, fire-resistant vegetation, patios, paving stones and other low-risk features in the zone immediately surrounding the home.
- Choose fire-resistant plants. Choose plants with low fuel volume or high moisture content. Avoid plants with high oil content or that tend to accumulate an excessive amount of dead wood or debris. The Bay-Friendly Landscaping & Gardening Coalition (www.BayFriendly.org) and the California Friendly Gardening Guide (www.bewaterwise.com) have information about fire-resistant plants.
- More tips. Don't plant trees and shrubs in locations where limbs and branches will reach the house or grow under overhangs as they mature. To minimize fire ladders, don't plant dense hedges or space tall vegetation too closely together. Use mulch (except fine shredded bark) and decomposed granite to control weeds and reduce fuel for fires. Construct roofs, siding and decks with fire-resistant materials (see our GreenPointers on Roofing and Siding and Decking. Consider alternatives to wood fences, such as rock or concrete walls.
Lawns are nice for recreation and relaxation. But keeping them looking good during California's long dry season requires a lot of time, money and resources. To reduce water use, eliminate the use of lawn chemicals, and cut down on maintenance, consider replacing all or some of your lawn with water-conserving California native groundcovers or perennial grasses, shrubs and trees. If you want some lawn, keep it small and locate it in a spot where it's most likely to be used for play and relaxation.
For those small lawn areas you retain, choose plant species that are native or regionally appropriate and don't need a lot of summertime water. Avoid planting grass on slopes greater than 10% or in irregularly shaped areas that cannot be irrigated efficiently. To avoid overspray from sprinklers, don't plant grass in isolated areas such as driveway strips or other areas less than 8 feet wide, unless they are irrigated with subsurface irrigation or micro spray heads.
Shade trees can create a microclimate that is up to 15°F cooler than the surrounding area, and can reduce a home's summer air-conditioning costs by 25% to 40%. Trees provide many other benefits including absorbing carbon dioxide, cleansing the air, creating habitats for birds and other animals, providing play places for children, making the neighborhood more beautiful and increasing property values.
Augment the existing tree cover on your property, particularly to the west of the home, by planting California native or other Mediterranean tree species that are drought tolerant and appropriate for the site's soil and microclimates. Plant trees to shade walls, windows and paved areas. If the home's design includes passive solar heating (see our Additions and Major Remodeling Overview), do not plant trees too close to the home's south side, or choose deciduous species that won't block the sun's warmth in the fall. Avoid planting trees too close to utilities or where they might shade solar panels. Plant a variety of trees and give them plenty of room to mature, reducing the need for pruning and shearing.
Different plants have different water requirements. Hydrozoning involves dividing the landscape into zones of low, medium and high water use matched to the needs of the plants in that area. This saves water and results in healthier plants that don't need to be replaced as often.
Group plants by water needs, creating irrigation zones based on the plants' water requirements and their exposure. If you are working with a landscape design professional, have them delineate each hydrozone on the site, irrigation and planting plans. Place thirstier plants in relatively small, highly visible areas and if possible, in spots that naturally collect water. Plant the larger areas with drought-tolerant species. Install separate irrigation valves for different zones. Some California natives do not tolerate water in the summer after they are established; be sure to separate them from plants that need ongoing irrigation.
High-efficiency irrigation systems
Efficient irrigation systems minimize overspray and evaporation and reduce runoff, dramatically reducing landscape water use while preventing disease and minimizing weed growth that results from overwatering.
Efficient irrigation systems include these products and benefits:
- Drip and bubbler irrigation products apply water to the soil at the plant root zones at the rate the soil can absorb it, and are often more appropriate than overhead sprinklers in areas that are narrow, oddly shaped or densely planted.
- Low-flow sprinkler heads apply water uniformly and slowly.
- Smart controllers regulate the irrigation program based on weather or moisture sensors, historic data or a signal. A rain sensor overrides the system in the event of rainy weather.
Adding good quality compost to the topsoil before planting brings life to the soil and feeds existing soil organisms, fueling many natural processes that supply nutrients, minimize disease and improve soil quality. Compost also increases the soil's permeability and water-holding capacity and makes nutrients more available to plants. This encourages healthy plant growth, improves the ability of the soil to filter pollutants, improves water quality, reduces irrigation needs and lowers water bills.
Topdress established lawns, shrubs and trees with good quality compost. For areas to be newly planted, incorporate 2 to 4 inches of compost into the top 6 to 12 inches of soil, or as much as is required to bring the soil organic matter content to 3.5% for lawns and 5% for planting beds, except for plant species that will not thrive in such soils. (You can send samples to a soil testing service to have it analyzed for texture, nutrients, organic matter content and pH.) Use fully stabilized, certified compost; stabilized compost has been properly matured and can be safely handled, stored and applied to the soil.
To reduce landscaping waste and make your own compost, designate an area on your property for composting plant debris.
Mulch is any material spread evenly over the surface of the soil. Mulch conserves water, reduces weed growth and simplifies maintenance. Organic mulch materials, including chipped landscape debris, are preferable over inorganic materials because they supply nutrients over time and provide wildlife habitat.
Apply and maintain a minimum of 2 to 3 inches of natural mulch to all soil surfaces or at least until plants grow to cover the soil. Do not place mulch directly against any plant stem or tree. Designate areas under trees as repositories for fallen leaves to remain as mulch. To further reduce environmental impacts, look for suppliers of mulch produced locally from urban plant waste debris.
Salvaged and recycled content materials
A variety of salvaged and recycled-content materials can be used for hardscapes such as patios, edging, walls, walkways and driveways and for other landscape features such as benches and play equipment. Broken concrete, for example, can be used to make a very attractive retaining wall or path. Tumbled recycled glass cullet can be used to create beautiful walkways or other decorative areas.
For outdoor uses, recycled-plastic lumber or recycled-composite lumber is generally much more durable than wood, because it does not rot, crack or splinter or require ongoing wood treatments. This material is commonly used for decking (see our GreenPointer on Siding and Decking) and makes a very durable landscape edging. If recycled-plastic or composite lumber is not appropriate, look for FSC-certified sustainably harvested wood; choose species appropriate for outdoor use.
Light pollution occurs when outdoor light fixtures let light escape onto neighboring properties and into the night sky. Reducing light pollution minimizes neighborhood or wildlife habitat disruption and saves energy.
To reduce light pollution, avoid using outdoor lighting where it is not needed. Rather than leaving outdoor lights on all night, use lighting controls such as motion sensors, timers and photosensors so that the lights are only on when and where needed (for more about lighting controls, see our GreenPointer on Lighting and Daylighting). Exterior lighting that provides low contrast on critical areas, such as pathways and home entrances, is better for visual acuity than overlighting.
Eliminate all unshielded fixtures that let light escape skyward or trespass on neighboring properties, such as floodlights. Look for fixtures certified by the Dark Sky Association for light pollution reduction (www.darksky.org).
Rainwater can be channeled through gutters and downspouts to an above-ground cistern or underground gravel dry well, and then used later for landscape irrigation. It can also be directed to bioswales or rain gardens. Rainwater catchment reduces the need to use municipal or well water for irrigating lawns and gardens, and reduces the volume of rainwater flowing into municipal stormwater or sewage systems.
Set up a system for rainwater collection wherever there is guttered roof runoff and room for a cistern, dry well, bioswale or rain garden. Bioswales are gently sloped drainage courses that slow the flow of rainwater, allowing it to percolate into the soil. A rain garden is a planted depression that absorbs or slows rainwater runoff.
More gardening & landscaping tips
- Learn more. The recommendations in this article are adapted from the Bay-Friendly Landscaping % Gardening Coalition (www.bayfriendly.org). Their website offers a wealth of resources suitable for most California climates, including lists of good plant choices, guidelines on how to compost, and advice on natural lawn care.
- Get paid to transform your landscaping. Some municipal water suppliers in California offer substantial rebates to homeowners who replace their lawns with water-efficient plants. Check with your water supplier before beginning a lawn conversion project. Also ask about rebates for water-saving products like weather-based irrigation controllers.