Your Questions

I’ve heard of a “rain switch”, do they work and where can I get one if they are effective?

I don’t have a lot of time to fiddle with my irrigation system.  It seems to work ok, but I need to save money where I can on my utilities.  Is there something quick and easy I can do?

Every time the sprinklers come on water runs down the gutter at the bottom of the hill. Our neighbors said we should rip out the sprinklers and put in drip irrigation, do we have to do that?

I want to plant some spreading groundcovers on the slope behind my house, what is the best way to irrigate them?

We moved into a house with a Toro ECx timer. The book that comes with it is confusing… can you help me set it up?

I have an automatic irrigation system and the irrigation is coming on every day.  Is this right, how do I know how often to irrigate?

Our gardener “fixed” our irrigation system last week, and now there is a different kind of pop-up sprayer in the lawn.  Is this right; does this make a difference?

How do I know when I have the right amount of sprinklers?

John's Answers

Jayne D., from Houston writes:

”We just moved into a new house, and the landscape has an automatic irrigation system.  The irrigation is coming on every day.  Is this right, how do I know how often to irrigate?“

Irrigation Essential's Response:

Jayne,
Lets start with the idea of irrigating roots.  Healthy roots make for healthy plants!

Shallow rooted crops (flowers and lawn for example) are likely to have roots in the top 2”— 8” of soil.  Shrubs are likely to have roots from 2” – 14”, or more, and trees as you might expect have roots that can extend far out from the tree and reach down several feet.

The “root zone” -- the area where the most roots are, is like a reservoir.  For your lawn for example, the reservoir is the entire area just under the soil surface, down 8” or so.  There is no point to irrigating so much that water percolates below the root zone.  Also, you never want to let a root zone become completely dry.  And, ideally you irrigate in such a way as to promote deeper roots, creating a bigger reservoir to enhance drought tolerance.

Inspect the root depth

I recommend examining the root depth with a soil probe, or shovel. (You can mail order for a soil probe at: http://www.gemplers.com or http://www.benmeadows.com.  A soil probe is inexpensive and enables you to inspect and verify what is happening in the soil.) Take a core before you irrigate, and turn the system on for 10 minutes.  Wait 20 minutes, and take another core sample.  How far did the water sink in?  Set an initial goal of filling the reservoir up.  This may entail another irrigation “start” (or cycle), after the initial water has soaked in.

A reasonable guideline for how long to wait before you schedule to irrigate again, is for half of the water in the root zone to be depleted.  (Remember – rainfall is part of the equation – turn off the system when you know it is going to rain!)

Plant Water need changes throughout the year

How often to irrigate will change throughout the year, but even in Houston, in peak summer turf can thrive on irrigation of 4 days per week, assuming even coverage, normal weather, and a deep soil reservoir.   Start in early spring with a reduced schedule, and gradually add start times and days on as you get to peak use in summer.  After July, gradually but steadily reduce your water applied – your landscape will continue to thrive, and over the course of a year you will save money on water!

To fully answer your question, we need some more specifics from you.  Email us back with the following information, and we can fine-tune an answer for you that will further save you money on your utilities, without any sacrifice in the look of your landscape.

1. What type of hardware:  spray pop-ups, or rotors?  Manufacturer?  Their programmed run times?
2. Controller:  Manufacturer & model and is it mounted indoors or outdoors?
3. Do you see any “runoff” or puddles after normal irrigation?
4. Your zip code (I can obtain your weather and soil data)?
5. Do you fertilize your landscape?  How often, with what?
6. Who do you buy water from—the name of your local water utility?

Saving Water is not just about irrigation hardware…

Soil Biology and Horticultural Practices–Easy Steps to a Beautiful Landscape!

You can use less water, and have a healthier landscape by building your soil.  Please see our article “Living Soil” for more detail on soil building.  Also, key horticulture basics:

• Use mulch over bare soil areas
• Cutting your lawn -- shorter in Spring & Fall, longer in the Summer
• Use a mulching mower, or simply make two passes and leave the clippings on the lawn (mow when the turf is dry) – this builds nitrogen in the soil!
• Use organic fertilizers, and eliminate the use of pesticides!  The water that migrates off your landscape takes trace elements of whatever you have applied with it!
   

System Management • Posted on 02/22/2009 •   Permalink

Many times, seemingly simple questions have answers that span several disciplines (design theory, installation practices, horticulture and soil science issues), and can become burdensome for someone to try to take in all at once.

To facilitate understanding, we group our information in three broad categories: 

System Management — Irrigation scheduling.  Hitting the “moving target” of plant water need as it changes throughout the growing season.

Delivery System — Spray heads, rotors, emitters, etc.  We try to explain the principles behind how they function, and make sense out of the many look-alike products on the market.

Soil Biology — Living soils and horticultural practices play a very significant role in how effective irrigation can be, and the viability of the landscape.  Think of growing roots, not plants!  Healthy roots will ensure a beautiful garden!