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How to water waterwise or California native plants

Waterwise and most California native plants require deep, but infrequent watering to be successful in gardens and landscapes. This is very different than the frequent shallow watering that turf and many traditional landscape plants receive. Read below to understand how to provide this in your landscape and why it is important.

WHAT IS 1” OF WATER?

To achieve a “deep watering,” your goal will be to apply about 1” of water over the entire area of the landscape where plant roots are growing, not just watering at the base of the plant.

When watering your garden, one inch of water is equivalent to a one-inch rainfall. Imagine a one-inch blanket of water hovering over your yard, then soaking in. When 1” of water is applied, it will wet the soil much further down than 1.”

The exact depth will depend on the soil type, but around 12” deep can be considered an average, depending on soil type and conditions. This will apply water to a significant amount of the active root zone for most plant species.

Apply water to the entire root zone

Deep, infrequent irrigation keeps plants healthy while saving water.

Waterwise and low-water native plants tend to have wide root systems that go beyond the edge of the canopy of the plants. For most established plants, the root zone can be considered to go about 1/3 further out from the edge of the plants canopy. Roots gather the most water and nutrients near the edge of a plant’s canopy and around 1/3 further back in and further out from the edge of the canopy. They tend to gather very little water directly at their base after they begin to mature. This is why we recommend watering with high-efficiency rotating nozzle sprinklers, “drip grid” systems, or approaches to hand watering that apply water either over the entire planted area or near the edge of plant canopies. Read on to learn more about the types of irrigation we recommend and don’t. 

While we usually recommend applying 1” of water for a “deep soak,” some landscapes may benefit from an even deeper watering, up to applying about 1.5” of water. The best way to determine this would be to dig in the soil in a few spots after applying 1” of water. If the moisture did not penetrate down to at least about one foot, your landscape may benefit from this even deeper watering. If you find that you need to apply over 1” of water when irrigating, it is often because your soil will hold on to more water per foot of soil depth. If that is the case, you may be able to go more weeks between waterings than our baseline recommendations for the watering frequency if you would be applying 1” of water. This is most common in heavier clay-type soils.

Important Note: The soil acts somewhat like a “water battery.” As the plants use water, the soil dries, “draining the battery” though the root zone of the soil. Deep waterings replenish soil moisture though the root zone “recharging the battery.” If for some reason, the soil gets severely dry, going longer than intended between waterings, you may need to provide additional water in the form of an extra deep soak irrigation to help fully “recharge” the soil moisture before returning to your normal irrigation schedule.

How Long Do I Water To Provide One Inch Of Water?

Providing one inch of water depends on many things related to your irrigation system and layout or your chosen approach to hand watering. You can figure out how to apply one inch of water to your garden by reading below.

RUN A SIMPLE “JAR TEST” AND TIME HOW LONG IT TAKES TO ACCUMULATE 1” OF WATER.

Before watering, lay out several 16 oz wide-mouth jars— or empty cat food or tuna cans. Be sure to layout out jars or cans in different areas of the garden and have some further away from sprinklers and some closer to the base of sprinklers because they may fill at different rates.

16 ounce wide-mouth mason jars can be used as an inexpensive way to track how much water you have applied with sprinklers or how much rain you received. The four-ounce mark measures approximately 1” of applied irrigation. They are usually available to purchase from Target or Walmart.
Turn on your irrigation zone and keep an eye on how much water they collect—they’re inexpensive rain gauges for your sprinklers.

Water until there is about one inch in each. This will be at about the four-ounce mark on 16oz wide mouth mason jars. Standard size cat food and tuna cans are about 1.25” deep.

 If certain jars have far less water in them when the others are around one inch, check to see if the sprinklers are all functioning properly or if the spray is blocked by a plant or other obstruction. If not, you have uneven coverage in the area and may need to change your sprinkler nozzle, add a sprinkler head, move a sprinkler head, or make other adjustments.

If you are using a permanent “in ground” sprinkler system, the number of minutes it takes to reach 1” of water in most of your jars or cans will be the length of time to water each time you want to “deep water.” 

If it works with your landscape area and the heights of the plants, high-efficiency rotating spray nozzle irrigation systems, mounted on 2’ high risers are a highly efficient systems with minimal maintenance needs and leak issues. They do a good job of mimicking natural rain and are a preferred method for watering waterwise or California native landscape areas.

If you are watering with a hose-attached adjustable sprinkler, it is best to set up a few jars each time you water, because small adjustments may result in needing to run the sprinkler for a different amount of time. We recommend always setting an alarm to remind you to check back – this is the best way to avoid forgetting and accidentally letting the sprinkler run all day or night! 

While more time-consuming to set up and adjust each time you water, high-quality hose-attached sprinklers can be an effective way to water relatively large areas of California native landscape when you will only be watering occasionally after the plants are established. This approach works best in areas where the sprinkler pattern can be adjusted to avoid watering pavement or unplanted areas. While there is more evaporation and wind drift using these types of sprinklers compared to permanent systems, they are easier to set up to elevate the irrigation above shrubs that would block spray nozzles and will never develop a line break or leak that goes undetected.

RUN THIS TEST FOR EACH ZONE / STATION OF YOUR SITE’S IRRIGATION SYSTEM

If you have different types of sprinklers or different sprinkler layouts in different areas of your yard, the number of minutes will be different for different areas, so it is best to test this for each zone of your yard.

It is important to realize that typical lawn sprinkler systems will not work if the lawn is being replaced with shrubs, groundcovers, perennial plants, etc. because the short 2” or 4” pop up sprinklers will be blocked as soon as the new plants start to grow, creating overly wet and very dry areas.

Using mason jars with a hose-attached sprinkler to know how long to water a back yard California native meadow.

DO YOU NEED TO “CYCLE AND SOAK”?

Depending on your irrigation system, soil, and slope of your landscape, you may not be able to water for the full amount of time it takes to apply 1” of water without water beginning to puddle and runoff. If you notice that water is doing this before you can apply 1” of water, you will need to use a technique called “cycle and soak,” which applies a portion of the water, then pauses to allow the soil to absorb the water, usually for about an hour, before continuing to water more. If you are using one, many irrigation controllers / timers have built-in functions to assist with setting up this process.

For information about watering system options for waterwise or California native landscapes and how to install them, check out our Retrofitting Turf Irrigation YouTube playlist.

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