Water Harvesting - The Arboretum
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Using topography, wood debris and mulch, we can actually save water and capture the rain that normally runs-off our landscapes.  Infiltrating water in the garden saves resources and can assist in recharging the water supply below ground.  This is what we call ‘water-harvesting’.

Using mulch as surfaces across the landscape also adds to the availability of water, as the beneficial microbes actually help release the volume of water available in wood debris, by breaking it down for food.  Read below about the techniques incorporated into our landscape that have resulted in a reduction of almost 70% irrigation use over time - from thirsty-lawn to the thriving, robust Crescent.

Lasagna Mulching

This technique is used to resuscitate a depleted landscape and also serves to destroy ornery weed problems. Sheet mulching is a quick way to add a lot of organic matter to the soil, improving its ability to hold water and enriching it with microbial diversity and mineral nutrients. It is the process of layering cardboard, mulch, and compost onto the soil surface. Learn more about how lasagna mulching works and how to do it yourself..


This is a passive water-harvesting technique pioneered in Europe.  It involves creating a mound of soil over wood debris which includes logs and branches, and green waste.  This results in increased moisture, as well as moisture retention.  It creates rich soil, adding valuable nutrients to the surrounding landscape. It can be planted, especially with food-bearing trees, saving resources and guaranteeing proper health. The Hugels at the Crescent are built using wood collected at the Arboretum - including from trees felled by the 2011 windstorm. We also have demonstration hugels inoculated with wood vinegar and biochar.  Come see our hugels and bring your questions.


Swales capture large amounts of water running off from slopes, rooftops, or streets, and they infiltrate that water into the soil, recharging groundwater. A swale is a trench or ditch dug into the soil surface along the contour of the land. It can be filled with rocks, logs, or mulch to facilitate water infiltration. Learn more about how swales work at the Crescent Farm and how to create your own.

Gravel Trenches

A simple and efficient way to drain standing water down a slope. A trench about 24” deep is filled with gravel and a perforated pipe to drain water away from an area and infiltrate it into the soil. This method is also known as a French drain. Learn more about how gravel trenches work and how to create your own.

Infiltration Basins

Water is channeled into a shallow basin where it will pool and infiltrate into the soil. The basin can be filled with rocks or planted with hardy species. Learn more about how infiltration basins work and how to create your own.


Terracing slows the rate of water running down a slope, and is a method of gardening on a steep slope. Soil erosion is controlled by shortening a long slope into a series of smaller steps. Slowing the rate of water gives it an opportunity to infiltrate into the soil. Learn more about how terracing works and how to install a terrace in your own garden.

Permeable Hardscape

Leaving space between pavers and using permeable material underneath, such as gravelly sand or loamy sand, allows water to sink in while providing a pleasing hardscaped surface. Vegetation can also be planted between pavers to enhance water infiltration and capture. Learn more about how permeable hardscapes work to infiltrate water and how to install your own.


An efficient irrigation system is one of the most significant components of a moisture-challenged garden. High-efficiency sprinkler heads along with spot-on watering techniques provide a strong base for a water-saving landscape. Check out this drought irrigation how-to guide.

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© 2024 Los Angeles County Arboretum and Botanic Garden • 626.821.3222 • 301 North Baldwin Ave, Arcadia, CA 91007

© 2023 Los Angeles County Arboretum and Botanic Gardens

Phone: 626.821.3222

301 N. Baldwin Ave, Arcadia, CA, 91007