The New California Landscape, part 3: Irrigation

Alas, irrigation is not the sexiest topic in this three-part series. It is, however, the most crucial element of any water efficient landscape (besides favoring drought-tolerant plants). An efficient irrigation system gets exactly the right amount of water exactly where it needs to be, with minimal losses to the street or gutter.

Taking steps to improve your irrigation requires you to pay attention rather than going into automatic mode. Here are things to look for when improving the efficiency of your system:

Stop overwatering!
Overwaterng is much too common. Lawns will be fine on two days a week in the heat of summer, and many established ornamental shrubs need less. The knee-jerk reaction to a limp plant is to grab a hose, but grab a moisture meter or a screwdriver instead and check the soil moisture several inches down.
Signs of overwatering resemble underwatering; ironically, both can lead to water uptake issues, the former because there is not enough water in the soil, the latter because root rot due to soggy, anaerobic soil reduces water-absorbing abilities.
If your lawn is dying on two days a week of water, there is most likely a cultural issue going on. It is better to water deeply but infrequently, rather than in short bursts several days a week. Shallow watering promotes shallow roots and drought intolerance. Check out the UC Integrated Pest Management Guide to Healthy Lawns for more information:

Proper maintenance
Do you know where your valve manifolds are? Do you know how to operate your sprinkler controller? Hopefully the answer is yes to both, because it will make testing and maintaining your irrigation system much easier!
Regularly check for leaks at all emitters and drip lines, and clean clogged heads and drip filters. Replace old, leaky hose spigots or hose washers that have become brittle and ineffective. Valve manifolds can also leak if sediment gets under the cap, leaking water even when turned off. This is tricky to spot and requires close inpection.
For information on irrigation:

Plants watered by the same valve need to have matching sun and water requirements, or someone is going to sulk (see overwatering section above). Do not water a sunny area and a shady area on the same valve, as the evaporation rates will be very different. It takes planning to do this properly, but will result in a healthier garden.
More information on hydrozoning can be found at:

Match emitter types
Avoid creating hodge-podge irrigation systems in which a broken emitter is replaced  with whatever is handy. Different emitters, whether drip or spray, have different water pressure requirements. Mixing things up often causes water to go everywhere (except where you want it).
Do not mix drip emitters with different flow rates on one valve. You can either place more emitters on plants that need more water, or divide two areas on the same valve using a barbed ball valve, available at irrigation specialty stores.

Run-off and puddling
We have all seen wet sidewalks and driveways when there was no rain, a sure sign that someone needs to adjust their timers! Concrete is not a living being, and so does not require hydration. Soils can only filtrate water so quickly, and run-off usually indicates too much water being applied all at once. Set your timer to water in cycles or switch to a type with a lower flow rate, such as drip or MP rotators for spray.
Puddling is caused by the same issue, and is exacerbated where there are low spots or the soil has been compacted after years of excess water and pedestrian traffic. Puddling can also occur at the base of a shrub that is blocking a sprayer. In the heat of summer, this water often evaporates before soaking into the ground.
Improving your soil can help with filtration:

For ornamental beds and vegetables, a 2-4 inch layer of organic mulch will help retain moisture, moderate soil temperatures, discourage weeds, and provide organic matter to improve soil aeration. Gravel is also good for moisture retention and temperature regulation in the winter. Avoid landscape fabric, which only works in the short-term to conrol weeds. Plastic inhibits rainwater filtration into the soil, looks unattractive, and creates a non-biodegradable mess as it wears down. Both make adding compost or other amendments difficult.

Re-thinking how we water our landscapes will be necessary for maintaining healthy gardens as the availability of cheap water becomes something of the past. Eliminating wasteful watering regimens and systems will be an important part of this transition, allowing us to retain the joy and beauty that plants bring to our lives.

If you have a gardening related question you can contact the UC Master Gardeners at 209-953-6112. More information can be found on our website.




This entry was posted in Uncategorized. Bookmark the permalink. Post a comment

Post a Comment

You must be logged in to post a comment.

We reserve the right to remove any content at any time from this Community, including without limitation if it violates the Community Rules. We ask that you report content that you in good faith believe violates the above rules by clicking the Flag link next to the offending comment or fill out this form.
  • Blog Author

    Nadia Zane

    Nadia Zane is a UC Master Gardener, a landscape designer and Stockton native. She has a fondness for California native plants and sustainable landscaping, which she utilizes in her work for Native Beauty Garden Design. She is a member of the CA ... Read Full
  • Categories

  • Archives