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When you compare how much water an efficient landscape design needs compared to your existing landscape, you can estimate your water savings. Landscape water savings

How Low Can Your Landscape Water Savings Go?

July 26, 2018/in Conservation Corner, Features /by Gayle Falkenthal

In places like San Diego County where water is a very precious resource, landscape designs that use the least potable water necessary are a growing part of the regional ethic. That means property owners should think about the efficiency and sustainability they can achieve in their landscaping.

As a general rule, it’s smart to maximize your ability to capture and use rainwater, and reduce, if not eliminate, your reliance on potable water for irrigation. When you compare how much water an efficient landscape design needs compared to your existing landscape, you can estimate your water savings.

To calculate landscape water use, the four key variables are:

Landscape Area (LA) – the square feet of area being landscaped with plants that require irrigation

Evapotranspiration (ET) – this is the number in inches based on your San Diego Climate Zone

Plant Factor (PF) – This is moderate, low, or very low depending on your plant selection

Irrigation Efficiency (IE) – There is no such thing as a perfect irrigation system. Many factors can limit efficiency and impact both your water use and the health of your plants.

Let’s assume your landscaped area is 1,000 square feet, with an ET of 51 inches annually, and IE of 0.7. Now, look at the difference your plant selection can make in water use:

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

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

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

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

Based on these examples, you could save 17,103 gallons of water every single year by selecting very low water use plants instead of high water use plants.

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.

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

Cook Up A Soil Lasagna

July 4, 2018/in Conservation Corner, Features /by Gayle Falkenthal

Healthy, living soil is full of oxygen, water, and life to support your plants. Building healthy soil using layers uses a process called soil sheet mulching, or “Soil Lasagna.” If you have ever cooked lasagna, this will seem familiar. Soil Lasagna boosts healthy microbes so much that they actually cook down the organic matter and start eating old grass in your landscape as food.

Once you’ve created Soil Lasagna, all you need to do is keep it moist so the microbes will stay active. How long the process takes from start to finish depends on the kind of grass you have. 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 in the delicious and healthy soil below.

Supply List to Create Soil Lasagna

- 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: If you need any permits, call DIG ALERT (8-1-1) two days in advance. Also, check with your local water agency for any local water use restrictions.

Once you have checked for permits and any water-use restrictions, you will need to remove your lawn. See our previous column on removing your lawn without killing the existing microbes. You will end up removing about six inches deep of grass and soil. You will need to haul this away. Consider renting a dumpster.

Dig a trench 8 to 12 inches deep (about one shovel depth), and 12 to 24 inches wide around any hard surfaces and building foundations. Also, complete contouring for rainwater absorption and retention and any other hardscaping such as moving or installing patios, paths and other features.

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

Layers Are Key To Your Soil Lasagna

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 you’re seeing why this is called a Soil Lasagna.

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

You can plant right through the Soil Lasagna layers. If you can wait, the soil will develop more healthy microbes for new plants, but you can plant right away if the grass has been removed.

Finally – step back and savor your hard work!

This article was inspired by the 71-page Sustainable Landscapes Program guidebook available at SustainableLandscapesSD.org. Hardcopies are available free of charge at the Water Authority’s headquarters, 4677 Overland Ave., Kearny Mesa. The Water Authority and its partners also offer other great resources for landscaping upgrades, including free WaterSmart classes at WaterSmartSD.org.

Conservation Corner-mulch-landcape-WaterSmartill you need? It depends on how you'll be using it in your sustainable landscaping. Photo: Phil Roeder/Flickr-Creative Commons License mulch master plan

More About Mulch You Need To Know

June 20, 2018/in Conservation Corner, Features /by Gayle Falkenthal

When using mulch in your landscaping, how much mulch do you need? It depends on what job you want it to perform.

To hold in moisture and keep down weeds: Use three to six inches of mulch on top of the soil.

To maintain planting beds: Maintain two to four inches of mulch on beds at all times.

Remember to keep mulch one to six inches away from plant stems. Mulch can cause plants to rot.

How Much Mulch Do I Need?

A few simple measurements and calculations will help you determine your mulch needs. Graphic: Water Authority

You first need to know these numbers:

Square footage of your landscaping
Thickness of your mulch cover in inches

Then take your square footage, multiplied by mulch thickness, and divide it by 12. This will give you your amount of mulch in cubic feet.

For instance, 891 square feet of land, multiplied by one inch of mulch, divided by 12 = 74.25 cubic feet of mulch.

Avoid These Mulch Types Around Plants

Inorganic mulches don’t decompose to feed soil microbes and keep your plants and garden healthy and thriving. There are also some organic mulches containing dyes or other chemicals. Other mulches, such as shredded redwood, take a very long time to break down. These are the types of mulches you should use only in areas without plants, such as in pathways or dry decorative areas:

Shredded redwood
Dyed wood mulch
Decomposed granite
Gravel
Rubber pellets

Compost vs. Mulch: What’s the Difference?

June 13, 2018/in Conservation Corner, Features /by Gayle Falkenthal

Compost and mulch may seem like interchangeable terms for the same thing. But they are two different things with different uses in your landscaping.

Compost is a soil amendment. It is made of organic matter such as food scraps, landscape debris, or livestock manure that have already been partially consumed and mostly decomposed by microorganism. You cannot tell the original source of compost. Good quality compost brings the helpful “OWL” formula of oxygen, water, and life together in one package.

Mulch is a soil topping. Mulch can be either organic or inorganic material that covers soil. The original recycled debris source of mulch is often identifiable. Mulch can be made from organic sources (grass clippings, leaf and yard litter, shredded wood trimmings) or inorganic sources such as gravel or decomposed granite (sometimes called “DG” for short).

The microbes in healthy, biologically diverse mulch will “knit” the organic material together, forming a thick blanket. This mulch cover protects the soil and plant roots from temperature swings, retains moisture by slowing down evaporation from the surface of the soil, and keeps weeds from sprouting by reducing sunlight penetration to the soil surface.

How to Use Compost

You can buy commercially produced compost, or you can make it at home. The compost-making process, or composting, involves creating the optimal conditions for the microbes to do their transformative work.

When compost looks like soil, you can work it directly into the soil. When compost is more coarse or has visible bits of the original materials, the most likely it is used on top of the soil instead of as an incorporated soil amendment worked in.

Compost works in several ways. The compost itself contains particles that improve soil structure. Next, as compost decomposes in soil, it encourages the formation of soil macroaggregates. These macroaggregates are composed of existing soil particles and decomposed organic matter, which combine to create a more stable and better-functioning soil structure.

How to Use Mulch

Mulch always stays on the surface of your soil. It is never worked in. Recycled organic material is the most effective type of mulch, because it builds soil structure over time and provides a durable, protective barrier. The smaller the debris pieces are and the more mixed the organic pieces are such as leaves with wood chips, the faster it decomposes. When building your soil, small mixed mulch is best.

Composted materials, especially coarse composts such as decomposed granite, can also be used as mulch. Artificial and inorganic mulches (DG, gravel, rubber chips) are mainly decorative. They do not contribute to soil life or plant health. They are best used in limited applications, such as creating natural pathways.

Use a soil probe to test how well irrigation dispenses into your landscape. Photo: Courtesy University of Florida/Creative Commons use soil probe

Take the Test: Use a Soil Probe

June 6, 2018/in Conservation Corner, Features /by Gayle Falkenthal

If you want to create a healthy, thriving landscape full of beautiful plants, you need to know how to use an important soil management tool: a soil probe.

Irrigation is essential to keep your landscaping green and growing. But to do so, you need to know as much as possible about your soils. One way is to use the Jar Test.

You should also use a soil probe. A soil probe lets you determine a lot more information about the soils in your landscaping. It helps you learn whether your irrigation water is successfully reaching the roots of your plants, or even if it soaks in too deep past the reach of plant roots.

Without a good picture of your soil profile, you can’t answer questions about effective irrigation. Variability across your landscape could result in different types of soils in different areas, or in soil layers extending different depths.

A good soil probe will help you figure out when irrigation water has reached the right depth for landscaping plants. It is a simple process with the right tools.

When your soil is moist, a soil probe should go into the ground easily. Your soil probe will stop when it hits hard, dry dirt and won’t go further.

How Low Should Your Irrigation Go?

If your probe stops, it could be hitting a rock, so you may want to reposition it a few inches away and try again. If you are confident you’ve just hit dry soil, put your fingers around the probe at the soil surface, and pull it out. Measure the depth in inches to learn how deep your irrigation penetrates the soil.

To properly irrigate your plants, understand the depth of their roots. Trees send their roots much deeper into the soil than shrubs, and shrubs have deeper roots than bedding plants like annual and perennial flowers or vegetables.

Most plants will do fine as long as the top foot of soil is filled with water when you irrigate. Shrubs should be irrigated to a depth of two feet, and trees irrigated to a depth of three feet.

You can purchase a soil probe at any general hardware story or gardening center. A basic soil probe costs between $30 and $80, but there are high-tech probes costing up to $300.

This article was inspired by the 71-page Sustainable Landscapes Program guidebook available at SustainableLandscapesSD.org. Hardcopies are available free of charge at the Water Authority’s headquarters, 4677 Overland Ave., Kearny Mesa. The Water Authority and its partners also offer other great resources for landscaping upgrades, including free WaterSmart classes at WaterSmartSD.org.

Three things are required for optimal garden soil: OWL, or oxygen, water, and life. Photo: SDCWA

Gardening Like A Wise Old OWL

May 30, 2018/in Conservation Corner, Features /by Gayle Falkenthalby Water News Network staff

Your landscaping soil needs three things to feed the billions of microbes within it that can transform brick-hard, lifeless dirt into healthy, living soil: Oxygen, Water, and Life. Or in shorthand: OWL.

Oxygen Lets Microbes Breathe Free

Oxygen is needed by plant roots and soil organisms. Healthy soil has lots of tiny pockets of air. When soils are eroded, graded, or disturbed, their structure becomes compacted and hard. Compaction takes place when air and water bubbles are squeezed out of the soil. This kills the healthy microbes that replenish soil. Microbes can be killed by fertilizers, pesticides, or even heavy traffic from people or vehicles.

Water For Your Microbes and Your Plants

Microbes and plants need water to live. But too much water in your soil will displace oxygen by saturating the soil. This creates an anaerobic condition — and unhealthy microbes like bacteria, viruses, or parasites prefer anaerobic soil. If this condition persists, diseases may develop that endanger the health of your garden.

Water is constantly moving through the soil. Water in the soil needs to be replenished as plants use it, as it evaporates from the soil surface, and as gravity pulls it down past the root zone of your plants.

Bring Your Soil To Life

Life in the soil includes all the bacteria, protozoa, nematodes, and fungi, the food they eat, the excretions they make, and the root systems they sustain. Living microbes are most quickly incorporated into your soil by adding high-quality compost.

Plants attract microbes to their roots by feeding them carbon. Bacteria and fungi hold the soil together with microscopic glues and binders. The microbes consume organic matter, and then they are consumed by bigger creatures (worms, ants, slugs, centipedes, larvae, etc.), which are consumed in turn by creatures further up the food chain.

Carbon and other nutrients cycle through these many life forms, creating healthy living soil, no matter what the soil type.

Without these three elements, landscaping will not thrive. Organic matter, planning and some labor may be involved, but creating healthy soil using the OWL method will pay off in reduced maintenance, reduced inputs, reduced pollution on land and in our waterways, and the beauty of your thriving, healthy landscape.

Get Your Free Sustainable Lanscapes Program Guidebook

This article was inspired by the 71-page Sustainable Landscapes Program guidebook available at SustainableLandscapesSD.org. Hardcopies are available free of charge at the Water Authority’s headquarters, 4677 Overland Ave., Kearny Mesa. The Water Authority and its partners also offer other great resources for landscaping upgrades, including free WaterSmart classes at WaterSmartSD.org.

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How Low Can Your Landscape Water Savings Go?