Water Neutral Gardens

Water Neutral Gardens (WNG) Components:

Design and Build Water Neutral Landscape Presentation

1. Plants: Selecting plants that require little water or none at all is an easy way to build a water neutral garden. California native plants are accustomed to being sustained with little rainfall. I have gardens that have irrigation systems that were used only for plant establishment. It is essential to understand your site. Where do you live? By the ocean, inland, in the mountains? There are multiple plant communities in California and the starting place is to know what was originally growing in your area. For example, I live in an area that is near the coast and was once grassland so there are the Coastal Scrub and Bluff Communities. My plant selections, therefore, could be from these groups.

Choose plants that are appropriate for your landscape

There has been much written on this topic and I would encourage you to read and browse these wonderful resources: California Native Garden FoundationCalifornia Native Plant Society, and a Yahoo Group: Gardening with Natives.

We could also select plants that are accustomed to growing in the climate zones we live in. I live in a Mediterranean climate and have selected plants that do well in rainy winters and dry summer (northern hemisphere).

Fruit trees can be water neutral and part of your edible garden

Fruit and nut trees as well as vegetables can be an integral part of a Water Neutral Garden and rainwater can be used for these edible portions of your property.

Soil is an integral part of your garden

2. Soils and Soil Structure and Texture: Soil plays an integral part in the success of a WNG. Do you know what type of soil you have? Time to get out a shovel and dig a hole. The deeper you go, the more information you will find. Were you even able to get your shovel into the soil, or did it bounce off? Need a pick? Sometimes soil that is uncovered will develop a hard crust and you will need this tool. Once you dig about 12 inches, you should be able to make some on-site discoveries. For example, what color is the soil? Usually, the darker the soil, the higher the organic content and this is good news. Lighter colored soils like beige, yellow, or red indicate a soil with less organic material and more mineral. Organic materials are important for plant nutrition and health. Now put some soil in your hand and roll it around. Does it fall apart easily? If so, it is more of a loam or sand variety. If it is sticking to your fingers and holds together when you squeeze it, that means you probably have a clay or clayey loam soil. The soil texture is important information. In most cases, a sandy soil drains quickly, a sandy loam soil, less quickly, in gradients all the way to clay which might drain a little or extremely little. Plants need air (gases) and water to survive and the type of soil texture and structure make a difference. With regard to WNGs, soils with some clay in them help hold water; and, of course, that is what we are looking for, contrary to many people’s opinions about clay.

Water table

Water Table: Some of this might seem fundamental. I am sure you will skip parts of this that you already know about. Having a high water table can be an advantage when developing at Water Neutral Garden and I recommend checking out this survey for information about your soils. There are simple instructions on how to zoom in on your property and discover what is really making your garden tick. So when you know your water table, you can understand that “impermeable surface at 80” will have a positive effect on your plants, if managed correctly. During a dry season, trees, shrubs, and even grasses can tap into this subsurface source to maintain optimal plant growth. Many older trees and shrubs have already done this and need little water. So find out about your soils and save a lot of money and time.

3. Greywater (manual, gravity, and pumping) My municipal water department sends 2.8 million gallons of potential greywater to the sewage treatment plant each day (39% of total “waste water).. This water could be used in our gardens that currently use between 30% and 50% of our total purified drinking water supply for their needs. Using potable water for our lawns ornamentals, and vegetables is a practice we need to change when so much greywater water is available. Note: it does use a lot of energy (30% in CA) to pump and purify our drinking water. In addition to this, we have over-drafted our aquifers and have even considered building desalinization plants to remove the salt from water, with damage to the environment and even more energy use. You can start to use greywater in your home right now.

Your house can be a goldmine for water.

Laundry to landscape water system

Here are some options: put a bucket in your shower to receive the cold water needed to have a warm shower. If you are a vegan, like I am, you can use the wash water from your kitchen sink to water your plants. You can hook up your washing machine to a pipe to water your garden. I currently water about 1/3 of my garden with water from my washing machine.


Water system installation

This type of system is permit-exempt and we can help you DIY or install a complete system ($50 per hour for phone consultation, $100 for a site evaluation, and $500-$1,800 for a complete system installation).

I also have an outdoor shower (cold water from the garden spigot) that I cleanup in every morning after a soak in my hot tub. Of course, you can take it a step further, by installing a branched drain system from your shower, bath, and bathroom sinks (see www.oasisdesign,net for complete plans and instructions.

The Cadillac of greywater systems

The Cadillac of greywater systems is the Aqua2use system that can transform your entire garden (sans lawns) into a WNG. It has the capability to water entire gardens using your shower/bathtub. bathroom sink, and washing machine. Most houses with slab foundations have their plumbing encased in concrete, making it difficult to plumb this type of system. This system can cost between $3,500 – $4,000 depending on the size of your garden. It is a permitted system that requires a complete design submitted for approval to the Environmental Health and Building Departments. Permit fees are included in the prices stated. See here for more information.

Capture water from your roof

4. Rainwater (passive and active): One of the most reasonable ways to water your garden is with the free water from your roof. Running the downspouts into areas of your garden can reduce the need for summer watering for at least 30 days and possibly more depending on the amount of recent rainfall. There are a few ways to do this. One is creating infiltration basins for the water to collect in. This is a basin up to 18” in depth made around trees and shrubs to collect water during the rainy season. Rainwater harvesting systems utilizing rain barrels or large tanks are also common and effective.

Mulching is king

Cardboard slows evaporation

5. Mulching: This is probably one of the easiest ways to reduce water use and do some other very important things in your garden like weed control and biological nourishment of your plants. I like to sheet mulch with cardboard from bike and appliance stores (larger sheets) or even from your grocery store (smaller pieces for around plants).

Laying the cardboard around your plants and covering it with 2 – 4” of wood chips from your local tree company, slows evaporation of soil moisture and keeps the soil evenly moist.

It is also one of the best ways to eliminate existing and future weeds. Earthworms and billions of micro-organisms love this environment and help develop humus as the cardboard and wood chips break down and they gobble any of the weeds and weed seeds. It is wonderful to know that this natural process is taking place instead of herbicides that actually kill micro-organisms and create what I call “dead” soil–soil lacking the abundant life of these organisms. These organisms also are key players in the transfer of nutrients from the soil. Carbohydrates developed by the plant through photosynthesis are exchanged for nutrients from the soil that have been transformed by micro-organisms to be more readily available for absorption. Scientists have discovered that this is one of the most efficient ways to nourish plants. And in this process you are  building plants that can withstand drought stresses.

Mulch slows water evaporation and looks nice!

There are other ways you can mulch your garden. Spreading a 2-3” layer of mushroom compost over all your planter beds will surprise you. This compost, that is available at most landscape supply centers, is reasonably priced (about $25 per cubic yard) and will provide your plants with nitrogen and other important nutrients. Most importantly, it is inoculated with beneficial mycellium that again will biologically activate your plant and the soil surrounding it. It also looks good around your plants by creating a uniform color and texture. Note: it smells like a farm for a few days. Firbark, redwood mulch, and cedar wood chips are other options that can be expensive. Avoid “Gorilla Bark” (redwood bark shavings), because it is hydrophobic (repels water). This will prevent the penetration of water by rain or sprinklers. It does a good job of keeping the soil dry around the plants, something we want to avoid.

6. Water Management techniques (monitoring individual situations)

7. Understanding shade and sun (different zone)

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