Posts

Use a variety of contouring methods in your sustainable landscape design. Photo: Water Authority

Contouring Tips Help You Make The Grade  

/in , /by

It’s smart to use existing depressions, slopes and contours for guidance when planning your landscape grading. If your yard is perfectly flat, you’ll need to move soil and features around to create more rain-holding contour areas.  

Do a Percolation Test, and prep your soil as needed to make it as much of a water-retaining sponge as possible before getting to work on rainwater capture plans.  

NOTE: If you are working with existing hillsides, it’s best to get professional advice before grading or other significant changes. Before any digging, call Dig Alert 8-1-1 or visit digalert.org  

Basins and swales 

Homeowners learn through the Water Authority's Landscape Transformation program that sustainable landscaping can be as lush as a lawn. Photo Water Authority turf

Basins and swales can take the form of dry creek beds, as in this award-winning water smart landscaping project. Photo Water Authority

Basins and swales are shallow depressions or channels no more than 24 inches deep on gently sloped or nearly flat landscapes. Basins and swales move water over short distances. The plants in and around the depressions capture and sink small volumes of surface water.   

Small, shallow depressions work best in clay soil areas, while sandy soils may accommodate deeper depressions up to two feet. Channels can be planted or lined with rocks and small boulders to resemble natural creek beds. 

Berms 

Berms are mounds of raised soil, usually planted, that can border basins and swales or be used alone. They help contain and move water around, increasing the holding capacity of basins and swales   

Boulders 

Boulders can add points of interest and slow down water runoff in your landscaping. Photo: Water Authority

Boulders can add points of interest and slow down water runoff in your landscaping. Photo: Water Authority

Boulders are useful to retain small berms or the edges of swales. They also create points of interest in your landscaping.   

This article was inspired by the 71-page Sustainable Landscapes Program guidebook available at SustainableLandscapesSD.org. The Water Authority and its partners also offer other great resources for landscaping upgrades, including free WaterSmart classes at WaterSmartSD.org.    

 

 

  

Using devices like this rain chain can help you slow and store rainfall for later use. Photo: Contraption/Flickr-Creative Commons License

Catch the Rain By Slowing and Storing It

/in , /by

If rain gutters are installed on your house, water will be directed into downspouts, where it can move with great force and speed. This is especially true in a large storm. Instead of allowing downspouts to discharge directly on hard surfaces like a driveway, path, or patio, think about ways to redirect downspout water into vegetated landscape areas. 

One option is to replace downspouts with “rainchains” to slow down the water so it can be more easily absorbed when it reaches your landscape areas. Add a rain barrel or cistern at the bottom of downspouts or rainchains and let it overflow into the garden. 

If rain gutters are not installed, water shears off roof surfaces and can cause erosion damage. Areas under the eaves may be covered in permeable groundcovers such as pea gravel, mulch, or rocks to reduce the compacting force of water falling on bare soil. Spreading fresh leaf and wood chip mulch throughout the garden will slow down water. Healthy soil can withstand even the strongest rain.   

Ways of storing rainfall  

Rainwater can also be harvested and stored. Storage vessels include rain barrels and cisterns directly connected to downspouts  

Stored water can be released gradually into the landscaping between winter rainstorms, building up the soil sponge and ensuring that native plants get adequate water during the winter months when they need it most. If you need water in the summer and capture enough of it during the winter, you may be able to use your cistern water for irrigation  

Both rain barrels and above–ground cisterns can be relatively inexpensive to purchase and easy to install. Mosquitos are kept out using screens. With minimum maintenance and common sense, the water can be kept safe. If you plan to store rainwater, make sure the “first flush” is diverted directly into the landscaping before capturing the rainfall that follows.  

Properly placed trees also are excellent landscaping features to help capture rainfall, allowing it to be released slowly over time into the soil.  

 

This article was inspired by the 71-page Sustainable Landscapes Program guidebook available at SustainableLandscapesSD.org. The Water Authority and its partners also offer other great resources for landscaping upgrades, including free WaterSmart classes at WaterSmartSD.org. 

  

 

 

The first rain after a dry period is called the "first flush." It can wash pollutants off hard surfaces. A better alternative is to filter the first flush through your landscaping. Photo: Skyloader.Creative Commons

Capturing the First Flush of Rainwater

/in , /by

The most important water to capture in your landscape is the first inch of rainfall after a dry spell. This is called the “first flush.”  

Rainfall in dry climates like the San Diego region is often a “first flush” repeatedly due to long stretches between rainy periods. 

The first rainfall washes away pollutants that have gathered on hard surfaces since the last rain. It needs to be filtered as much as possible by landscaping before it goes anywhere else, especially into storm drains that empty into the oceans. 

How much water comes off your roof? 

The shape of your roof doesn’t make any difference. The same amount of water falls on the roof whether sloped or flat. Measure a sloped roof either using an aerial view or from the ground without worrying about the slope itself. Just measure the outside edges the same way you would if it was flat, and calculate the square footage. 

Flat roofs covering a building in one contiguous shape are easier to measure. Some roofs are more complicated. Divide this type of roof into individual squares or triangles. Measure each one at a time, then add the figures together for your total roof area.  

Calculate your potential water capture  

Once you know the total roof area, you can determine the amount of rainfall it generates in gallons, then use the following formula to convert square feet to gallons.  

Formula: Rainfall in Inches x Total Square Feet x 0.62 = Gallons of Rainwater From the Roof 

Example using a 1,000 square foot roof: 1 inch of rain x 1000 x 0.62 = 620 gallons. 

San Diego’s rainfall total for “water year” 2018 was about 3.3 inches. Imagine this amount falling on a 1,000 square-foot roof. The total amount of water runoff during this water year would be 3.3 X 1000 X 0.62 = 2,046 gallons.  

Even in our dry climate, this rainfall adds up to a lot of water runoff. It’s easy to see how important it is to save as much of this water as possible in a landscape designed to be a sponge instead of a brick.  

 

This article was inspired by the 71-page Sustainable Landscapes Program guidebook available at SustainableLandscapesSD.org. The Water Authority and its partners also offer other great resources for landscaping upgrades, including free WaterSmart classes at WaterSmartSD.org. 

 

 

 

To properly capture water flow from rainfall, you need to assess where it naturally flows first. Photo: Tae Wook, Creative Commons License

Where Does Water Flow in Your Landscaping?

/in , /by

To capture rainwater and any excess irrigation inthe soil or rain barrels, it is first necessary to understand what happens when water comes off the roof of buildings and moves across the property.  

Where is water moving? 

Make a copy of your landscaping site plan, and label it “Water Plan.” It should have the position of the buildings and major landscaping structures. During a rainstorm, watch what happens to water as it comes off the roof of the house and moves through the property. 

  • Are there any low spots where water pools? 
  • Does water run entirely off the property anywhere? 
  • Do any buildings or hard surfaces such as patios appear to be damaged by water? Is the damage caused by rain, by irrigation, or by both?

Note the direction water moves around the property from one area to another, or through multiple areas. 

Turn on irrigation systems for three minutes, and make a note about where there is any pooling or runoff.  

Assess the downspouts for water volume

Use the following process to figure out how much water comes off any hard surface, whether it is a roof, patio, driveway, or sidewalk. 

First, imagine the total roof area of your garage is 20 by 20 feet square, or 400 square feet, and water flows off it in two downspouts.  

If half the water goes into each downspout, the roof size for one downspout is half your total area. In this example, that is 200 square feet. 

Multiply the square footage for your downspout area by 0.62 to get the gallons of water per inch of rain coming from your downspout. Using our example of 200 square feet, the formula is 200 x 0.62 = 124 gallons.  

Once you have this number, you can plan for the resources needed to capture this water runoff for later use using tools such as rain barrels.  

 

This article was inspired by the 71-page Sustainable Landscapes Program guidebook available at SustainableLandscapesSD.org. The Water Authority and its partners also offer other great resources for landscaping upgrades, including free WaterSmart classes at WaterSmartSD.org. 

 

 

 

A simple, quick test will tel you how well your soil drains. Photo: Greywater.org landscape soil

Take a Soil Percolation Test

/in , /by

In the San Diego region, rainfall can be unreliable and insufficient to sustain landscaping without careful planning and a little help. An alternate water source, such as irrigation, may be required.  

To make choices about the best, most efficient irrigation system for your landscape, it’s important to learn how well your soil drains.  

How does your drainage perform? 

Assessing how well water drains through your soil involves a simple percolation or drainage test. Follow these four steps: 

1) Dig a hole the size of a one-gallon plant, about 12 inches deep and 12 inches wide. 

2) Fill the hole with water and wait. Time how long it takes the hole to drain completely. This is needed to saturate the soil. 

3) Once the water has drained and none is visible in the hole, fill the hole with water again.  

4) Lay a stick or a shovel handle across the top of the hole, and measure the distance from the top of the hole at the handle or stick to the top of the water once every hour until it drains completely the second time. You may want to set a timer so you don’t forget to make your measurements. 

Percolation and soil quality 

If your soil drains more than four inches per hour: You have sandy soil. You need to add organic matter to improve the soil.

If your soil drains less than one inch per hour: Your soil needs extra help to drain. Try sheet mulching (link to page 19) 

If your soil drains from one to four inches per hour: Good news, your soil is a sponge and drains well. This is the goal.    

It isn’t difficult to build healthy, well-draining soil. Get our tips on how to create health soil here.

 

This article was inspired by the 71-page Sustainable Landscapes Program guidebook available at SustainableLandscapesSD.org. The Water Authority and its partners also offer other great resources for landscaping upgrades, including free WaterSmart classes at WaterSmartSD.org. 

 

 

 

Capture as much rainfall runoff as you can and put it to use as landscape irrigation. Photo: StevePB/Creative Commons rainfall as resoure

Rainwater as a Resource for Your Landscaping

/in , /by

During the rainy season, runoff from hard surfaces around the home such as roofs and patios can be directed to the permeable landscaping. By capturing as much rainwater as possible in the soil, it is possible to build an ecosystem that can last through the summer months with minimal additional irrigation.  

The entire built environment can be re-imagined and transformed into a living sponge. If more rain falls than can be absorbed, or if the soil is particularly impermeable, rainwater can be directed through landscaped areas to remove pollutants before it flows downstream. 

Adjusting systems to maximize rainwater capture

There are three basic steps to capturing rainwater. First, check your roof to determine where precipitation is directed after it hits the surface — whether into rain gutters, off the edge, or elsewhere. Second, choose how and where to hold excess rainwater based on this assessment. Last, consider making upgrades such as adding rain barrels or making changes in your landscaping. For instance, landscaping soil may need amendments to hold more water. 

Is your soil more like a brick or a sponge? 

If your soil is more like a brick, it will affect how landscaping is contoured to capture water. Adding soil amendments will help it become more like a sponge that retains water for drier weeks and month. If the soil doesn’t drain well, take special care to avoid drowning new plants. 

When choosing landscaping plants, match them to the soil type. If the soil is sandy, look for plants with “dry feet” that prefer free-draining soil, If the soil is harder clay, look for plants that do not mind heavy soil.

Optimal landscape soil can capture rainwater and allow it to soak in completely in 24 to 48 hours.  

Many homeowners also use rain barrels to capture rainfall before it reaches the ground so it can be released during dry times. For more information about rain barrels, go to WaterSmartSD.org for information about purchase, rebates, and a one-minute video guide to installation.

 

This article was inspired by the 71-page Sustainable Landscapes Program guidebook available at SustainableLandscapesSD.org. The Water Authority and its partners also offer other great resources for landscaping upgrades, including free WaterSmart classes at WaterSmartSD.org. 

 

 

Overwatering-drought-landscaping-Conservation Corner

Does Your Landscaping Need Water?

/in , /by

Before adding irrigation to landscaping, make sure it’s needed. Appearances can be misleading, and cause water to be used unnecessarily. 

First, use “digital” technology. Because soil may appear dry on the surface, stick your finger into the soil and see if the soil is wet beneath the surface. If the soil is moist up to your second knuckle, it doesn’t need any more water. Wait for another 24 to 48 hours, and check the soil again. 

As an alternative, use a soil probe and measure the moisture in the soil to determine whether the soil needs more water.  

Another strategy is to assess plant health. How vibrant are they? This can be tricky, because sometimes the signs of overwatering and underwatering will produce similar results in plants.  

Underwatering symptoms include: 

  • Soil is bone dry 
  • Older leaves turn yellow or brown, and drop off 
  • Leaves are wilted 
  • Leaves curl and become brittle 
  • Stunted plant growth

Overwatering symptoms include: 

  • Soil is constantly saturated and soggy 
  • Leaves turn a lighter shade of green, or turn yellow 
  • Younger plant shoots wilt 
  • Leaves are green and brittle 
  • Algae and mushrooms are in the soil 
  • Growth is excessive 

Since the symptoms at both extremes can be similar, it’s best to rely on objective measurements rather than observations. Using simple measurement tools can help ensure the correct amount of irrigation takes place without withholding needed moisture, but without overwatering and wasting resources.  

 

This article was inspired by the 71-page Sustainable Landscapes Program guidebook available at SustainableLandscapesSD.org. The Water Authority and its partners also offer other great resources for landscaping upgrades, including free WaterSmart classes at WaterSmartSD.org. 

 

 

Maximize your landscaping soil's ability to retain and save rainfall and irrigation for drier days. Photo: D. Douk/Creative Commons

Building a Water Savings Account

/in , /by

Managing water wisely in a landscape is a lot like managing a bank savings account.  

Approximately half of the water spent by average California homes is used outdoors, mostly for irrigation. Unfortunately, up to half of commercial and residential irrigation water is squandered by evaporation, wind, improper system design, or overwatering, according to the U.S. Environmental Protection Agency.  

Using landscape irrigation efficiently can significantly reduce overall household water consumption while leaving adequate water in the ground to cover your plants’ needs. 

During the winter in metropolitan San Diego County, healthy soil can absorb water in surprisingly large quantities to be released slowly to plants as they use it during drier months – like using a savings account to pay for expenses over time.  

That’s particularly true during wet spells like we’ve had in late November and early December 2018; no need to spend irrigation water when Mother Nature is making the deposits for you. 

Balance your water bank account 

Water that enters the soil as rain or irrigation is like a deposit into a soil checking account.  

By keeping track of those transactions of water in and water out, it is possible to know how much water in the soil “reservoir” is available in the landscape at any given time for the plants to access. 

The initial soil bank balance is determined by direct observation or is assessed after a thorough wetting of the soil by irrigation or winter rains. Every day, plants take small amounts of water from the soil. Rain and irrigation fill up the water bank again. The trick is to make sure this “account” does not get overdrawn. 

How can you tell when the account is depleted? Smart irrigation controllers and landscape professionals can calculate this for you. You can also rely on a soil probe, or even testing the landscape by feeling the soil surface with your fingers. 

 

When oxygen and water are balanced in the soil, the amount of water lost through evapotranspiration is similar to paying fees on your savings account. Shading the soil surface with plant materials and mulch protects water in the soil by slowing evapotranspiration and leaving more water in your soil’s account. 

 This article was inspired by the 71-page Sustainable Landscapes Program guidebook available at SustainableLandscapesSD.org. The Water Authority and its partners also offer other great resources for landscaping upgrades, including free WaterSmart classes at WaterSmartSD.org. 

 

 

Give new landscaping plants plenty of room to grow and thrive. Photo: Water Authority

Give New Landscape Plants Space To Grow

/in , /by

When choosing plants for new sustainable landscapes, it’s important to account for the height and the width of each plant species when it matures. This allows you to properly space plants in the landscape without having them feel crowded.  

Proper plant placement, taking into account the mature plant’s size, also should limit the need for future pruning, and reduce the amount of maintenance required in the long run. 

Natural plant shapes and sizes maximize habitat value, but wildfire prevention requires regular pruning and removal of dead plant materials.  

The spacing chart below helps to judge how many plants are needed per square foot, based on the mature size of the plants.  

Space plants on your landscaping plan at their full mature size, not the size when you first plant them. Graphic: Water Authority

Space plants on your landscaping plan at their full mature size, not the size when you first plant them. Graphic: Water Authority

Scale your plants at maturity 

On your landscaping plan, use circles to note the size of every plant at maturity using a scale in which one inch equals four feet. Use colored pencils to note different water needs of the plants selected. It will make it easier to group plants into their proper irrigation zones (hydrozones).

Wide canopy trees that grow to 20 or 30 feet in diameter will significantly change the landscaping over time. Consider whether a tree will cover a large section of landscaping with shade that is currently getting full sun. If plants that thrive in full sun are eventually covered in shade, the landscaping may need to be revised in the future.  

Small but mighty 

Select the smallest, healthiest plants possible, especially when choosing native plants. Once they are planted in properly prepared soil and watered wisely, small plants establish themselves more vigorously than plants raised in larger containers. Do not plant more than the space allows when the plants mature. 

Root depth matters 

Take note of the root depth of plants when they are placed into the landscaping. Note root depths on your landscape plan. Trees will be irrigated less frequently, but for a longer period of time. Groundcovers with shallower roots require more frequent, shorter periods of irrigation. Keep these types of plants in separate hydrozones.  

 

This article was inspired by the 71-page Sustainable Landscapes Program guidebook available at SustainableLandscapesSD.org. The Water Authority and its partners also offer other great resources for landscaping upgrades, including free WaterSmart classes at WaterSmartSD.org.    

 

 

  

Mirroring Native Plant Communities in Sustainable Landscaping

/in , /by

In nature, plants arrange themselves into communities of “friends” based on common microclimates, water and nutrient needs, and how they interact with the physical environment. Native plant communities also are based on interactions with each other and other species such as insects, birds, and other animals.

Most plant communities occur repeatedly in natural landscapes under similar conditions.

Local native plant communities have evolved together over a long period of time, and grow well together. They will even “reject” the outsiders and work together to compete for nutrients, sunlight, and other resources

This is one of many good reasons to learn about the San Diego region’s native plant communities and to select plants that like to live together in communities for sustainable landscaping.

Three examples of San Diego regional plant communities

California Coastal Prairie Community

California Coastal Prairie along the coast north of Jenner, California. Photo: Wikimedia/Creative Commons

California’s coastal prairies are the most diverse of any grassland in North America. Perennial flowers outnumber grass species here. Plants include: California Poppy (Eschscholzia californica), Blue-Eyed Grass (Sisyrinchium), Fern Leaf Yarrow (Achillea ‘Moonshine’), Seaside Daisy (Erigeron glaucus), and Cliff Buckwheat (Eriogonum parvifolium)

California Coastal Sage Scrub Community

California Coastal Sage Scrub in the San Pasqual area. Photo: Barbara Kus, USGS/Creative Commons

California Coastal Sage Scrub in the San Pasqual area. Photo: Barbara Kus, USGS/Creative Commons

California coastal sage scrub features fire-adapted, drought deciduous plants, which are rapidly disappearing to urbanization in southern California. Fortunately, some areas, including the San Diego Safari Park Biodiversity Reserve, have been conserved. Plants include: grey musk sage (Salvia Pozo Blue), sticky monkeyflower (Diplacus aurantiaus), San Diego sage (salvia munzia), fuschia gooseberry (Ribes speciosum), and woolly bluecurls (Trichostema lanatum)

California Chaparral Community

California Chaparral near the University of California, San Diego. Photo: UCSD/Creative Commons

Chaparral exists in many coastal ranges, and on the western and eastern slopes of the southern California mountains. It is ‘hard’ brush that doesn’t rely as much on summer fog as the Coastal Sage Scrub does, and it is adapted to heat and drought. Plants include desert mallow (Sphaeralcea ambigua), bent grass (Agorstis pailens), San Diego mountain mahogany (Cercocarpus minutiflorus), bush poppy (Dendromeconi riguda), and clumping wild rye (Leymus condensatus),

 

This article was inspired by the 71-page Sustainable Landscapes Program guidebook available at SustainableLandscapesSD.org. The Water Authority and its partners also offer other great resources for landscaping upgrades, including free WaterSmart classes at WaterSmartSD.org.