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Grouping plants together by water needs by matching microcliimates creates efficient irrigation. Photo: Water Authority

Microclimate Matching in Your Landscaping Plan

Earlier in our Conservation Corner series, we described how to map the different types of microclimates present in your landscaping. Using this information helps homeowners arrange plants in a new sustainable landscape. For the most efficient water use, plants should be grouped together with similar water needs according to their preferred microclimate.

In nature, plants that like lots of water are found along the banks of a stream, or grouped together at the base of a depression. Plants that need fast-draining soils so roots don’t rot might be found on hillsides. Plants that love lots of sunshine won’t grow in the shade of a tree.

Follow The Microclimate Map

Look to the Microclimate Map for smart guidelines on choosing landscape plants. Consider this example yard with three identified microclimates:

  • A front yard in full sun most of the day.
  • A moist depressed area in full sun. This area will retain moisture more than the rest of the yard, so you could use this area for rain catchment. Raise hillside areas surrounding the depression and allow them to drain freely.
  • A shady area under the canopy of a neighbor’s large tree.

Three Different Plant Neighborhoods

Areas of your landscaping under large shade trees become individual microclimates. Photo: Ken Lund/Creative Commons License

Areas of your landscaping under large shade trees become individual microclimates. Photo: Ken Lund/Creative Commons License

When selecting landscaping plants, the yard in this example will require at least three different groupings of plants.

  • Sun-loving plants that prefer their roots dry and in fast-draining soil
  • Sun-loving plants tolerant of wet feet in winter months, which thrive in heavier clay soils
  • Plants tolerant in dry shaded areas

A final consideration before heading to the local nursery or garden center: how will you irrigate your plants?  Check the Plant Factors for each of the plants to make sure their water needs are all similar in each area. A previous Conservation Corner feature has information about Plant Factors.

Plants Speak Latin

Many plants have similar common names in English. Shopping for plants by their common names can lead to confusion between two very different plants. Instead, the best way to shop for plants is to use the Latin name. This reduces any miscommunication and any surprises in your landscaping. 

This article is part of a year-long series 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.

An example of drought tolerant landscaping with low water use plants. Photo: Kelly M. Grow, California Department of Water Resources landscape conserve

How Much Water Can Your New Landscape Conserve?

Landscape designs using the least amount of potable water necessary are greatly encouraged in arid or Mediterranean climates like in San Diego County. It’s an important motivation for homeowners to consider efficiency and sustainability to lower water use, saving a precious resource.

Maximizing your landscaping’s ability to capture and use natural rainfall can also help reduce or even completely eliminate your reliance on potable water for irrigation.  Compare how much water your new landscape design will need against your existing landscaping’s water use. You’ll be able to estimate your future water savings.

Start by calculating the water use requirements of landscaping filled with plants that require high amounts of water, or moderate amounts, low or very low water requirements.

In these examples, evapotranspiration (ET), irrigation efficiency, and landscape area are exactly the same. The only difference: our examples are home to plants with different water requirements.

How to calculate your landscape’s water use

To calculate water use, you can refer to the San Diego Water Efficient Landscape Ordinance for guidance. Go to www.sdcounty.gov and search “Landscape Ordinance.” The four key variables are:

  1. Landscape Area (LA) – the square feet of area being landscaped with plants that require irrigation
  2. Evapotranspiration (ET) – this is the number in inches based on your San Diego Climate Zone
  3. Plant Factor (PF) – This is moderate, low, or very low depending on the plant selection
  4. Irrigation Efficiency (IE) – There is no such thing as a perfect irrigation system. Many factors can limit efficiency and impact your water use and the health of your plants.

Use a landscaped area of 1,000 square feet, with an ET of 51 inches annually, and IE of 0.7. Look at the big difference your plant selection can make in your water use.

Example 1: High Water Use plants (PF = 0.8) – 36,137 gallons of water per year

Example 2: Moderate Water Use plants (PF = 0.5) – 22, 586 gallons of water per year

Example 3: Low Water Use plants (PF = 0.2) – 9.034 gallons of water per year

Example 4: Very Low Water Use plants (PF = 0.1) – 4,517 gallons of water per year

From the highest estimate to the lowest estimate, you could potentially save 17,103 gallons of water every single year.

This article is part of a year-long series inspired by the 71-page Sustainable Landscapes Program guidebook. The Water Authority and its partners also offer other great resources for landscaping upgrades, including free WaterSmart classes at WaterSmartSD.org.

Create a healthy growing environment for your new landscaping with the "soil lasagna" method. Graphic: Water Authority

Soil Lasagna Cooks Up A Tasty Landscape

Healthy, living soil is full of oxygen, water, and life to support your plants. This is the food your plants need to consume for good health. Creating healthy soil in layers is referred to as soil sheet mulching, or “soil lasagna.” It isn’t too much different than cooking a pan of lasagna in your kitchen.

Soil lasagna increases healthy microbes so much, they actually cook down the organic matter and start eating up old grass in your landscape as food.

All you need to do to encourage the active benefits of soil lasagna is keep it moist. The length of time for soil lasagna to provide the maximum benefits start to finish depends on the kind of grass you have.

Supply list to create your soil lasagna

With just a little investment of time and effort, you can create the healthiest foundation for your new landscaping. Photo: Goumbik / Pixabay

  • Shovels and rakes
  • Wheelbarrow(s)
  • Bins to hold removed grass and soil
  • Mulch
  • Landscape flags
  • Painters’ paper or large cardboard sheets
  • Compost, worm castings, or compost tea
  • Hose with a shutoff nozzle

NOTE: Consider first whether you need any digging permits. If yes or you aren’t sure, call DIG ALERT (8-1-1 or  800-422-4133) two days in advance. Check with your local water agency for any local water use restrictions.

Once you have checked for permits and any water use restrictions and remove your lawn, you’re ready to get started. Remember, use healthy removal methods to set your landscaping up for success. Expect to remove and haul away about six inches deep of grass and soil. Rent and fill a dumpster which can be picked up and disposed of responsibly later.

Dig a trench eight to 12 inches deep, about one shovel depth, and at least 12 to 24 inches wide around any hard surfaces and building foundations. You need to complete contouring for rainwater absorption and retention and any other work to hardscaping such as moving or installing patios, paths, and other features.

Use the landscape flags to mark sprinkler heads so you can find and adjust them later.

Layers supply the magic

Create a healthy growing environment for your new landscaping with the "soil lasagna" method. Graphic: Water Authority

Create a healthy growing environment for your new landscaping with the “soil lasagna” method. Graphic: San Diego County Water Authority

Add an inch deep layer of compost on top of the graded soil. You can also use humates, a freeze-dried compost available at specialty landscaping stores, or spray with compost or worm tea. You are adding an instant food sources and additional microbes to the soil.

Water thoroughly. Roll out your painters’ paper or cardboard. Overlap at the seams about six inches and be sure all of the soil is covered. At the hardscape borders, make a burrito of rolled paper and mulch to prevent grass from resprouting.

Water the paper, and then add another layer of compost if you wish. Rake a thick, six-inch larger of mulch over the paper and compost. Now it should seem obvious why this is called a Soil Lasagna.

Water again thoroughly. The mulch will absorb a lot of water before it becomes thoroughly soaked through.

When you are ready to plant, you can dig a hole right into it, cutting through any paper or cardboard that might still be there, planting into the delicious and healthy soil below. Allow as much time as you can so your soil develops more healthy microbes for your new plants. But you can plant right away if all grass has been removed and you’re short on time.

This article is part of a year-long series inspired by the 71-page Sustainable Landscapes Program guidebook. The Water Authority and its partners also offer other great resources for landscaping upgrades, including free WaterSmart classes at WaterSmartSD.org.

Setting Your Landscaping Objectives for Success

When you’ve taken the time to learn about the concepts behind the watershed approach to creating a healthy and sustainable landscape, you should step back and consider the goals you want to achieve in your garden.

If you’re facing an ocean of grass lawn and you’ve never given much thought to landscaping goals, it might be difficult to know where to start. Here are a few ideas.

Saying goodbye to grass

Remove a thirsty lawn without using any chemicals, in a way that preserves the healthy soil microbes.

Plant local California native plants that will attract birds, butterflies, and bees for pollination.

Create a child or pet friendly garden without thorns or sticky grass seed heads.

Plant fruit trees, edible vines and shrubs, or vegetable gardens.

Using water efficiently

Build healthy living soil that will act like a sponge, even if it rains a lot.

Capture all the rainwater from the roof and re-routing downspouts to fill rain barrels instead of running onto hardscaping.

Convert spray irrigation to micro or drip irrigation, with the intention of turning it off after establishing low-water use landscaping.

Make pathways and driveways more permeable.

Create a garden as a personal art gallery

Make room for a small patio with room for an outdoor table or seating.

Add pathways, Zen gardens, and interesting materials and patterns.

Integrate beautiful objects such as an art piece, interesting container collection, or items like sundials.

One goal we can all support: creating a beautiful sustainable landscape that reduces your water use by 70 percent or more.


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

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.