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desert-landscape

“How much water do my plants need?”

I am often asked this question by desert dwellers and my answer is always, “That depends.”

desert-landscape

There are several variables that determine how much water plants need, along with the frequency of watering.

Variables include:

  • Type of soil (clay, sand, combination)
  • What kind of plant (native plants, higher water use flowering shrubs and ground covers, succulents, etc.)
  • Recommended depth of water
  • Desert region (low-desert, mid-altitude, high desert)
  • Efficiency of irrigation system
  • Water pressure (can vary between neighborhoods)
As you can see, there is no universal watering guideline in regards to how long to water or how often.

Let’s look into the variables a little more closely to help you determine what yours are:

 

SoilClay soils hold onto water longer than sandy soil. They take longer for water to permeate to the recommended depth. The result? Clay soils need irrigation less often than sandy ones but need to be watered for a longer length of time. Phoenix area soil tends to have more clay in them while those in the Palm Springs area are sandy.

Plants – Native or desert-adapted plants need less frequent irrigation versus those that come from tropical climates. Cacti and other succulents do well with infrequent irrigation.

Water Depth – Trees need to be watered deeply while ground covers and succulents do fine at a more shallow depth – shrubs fall in between the two.

Desert Region – Where you live in the desert matters when it comes to water and your plants. The differences include rainfall amounts, when the rain falls, high and low temps, and more. Residents of low-desert cities like Palm Springs and Phoenix need to add water to their plants more often than those who live in higher elevation regions such as Tucson.

Irrigation System – The older your irrigation system, the less efficient it is. This is due to mineral build-up within the system, which affects the amount of water that comes out. Also, old drip irrigation systems tend to accumulate leaks. The average lifespan for a drip irrigation system is 10-15 years. 

Despite these differences, what is a shared characteristic is that the vast majority of desert residents water too often and not deeply enough. This is usually due to lack of knowledge and thinking the ‘more is better,’ especially in the desert.
Landscapers are generally not a reliable source when it comes to scheduling irrigation – most recommend irrigating far too often.
 
So what is a desert dweller to do?
Thankfully, there is very useful information available for homeowners to help them figure out when and how much water their landscape needs.
 
Major metropolitan areas throughout the Southwest have excellent watering guidelines available for residents. The guidelines include the regional variables we have discussed so far.
Here are helpful links based on major desert cities (click the link for the city closest to you):
Watering guidelines are just that – guidelines. Circumstances may mean that you need to water more or less often, but these guides are a useful baseline to work from.
*One final note – before you implement a new irrigation schedule, it’s important to gradually wean your plants to the new one over several weeks. The reason for this is that it allows plants to become accustomed to the new schedule.

Yes, it does take a little work to figure out how much and often to water your plants, but these guides are incredibly helpful and will guide you along the way.

What is wrong with the picture above?
 
A few days ago, I decided to start writing about some of the “landscape no-no’s” that I see when I am doing landscape consults.
From time to time, I will focus on a particular “landscape no-no” and its solution.
My hope is that it will help you to avoid or fix these problems.
My first “landscape no-no” post, featured the photo above.  Readers were invited to figure out what was wrong and leave a comment.
Quite a few of you left comments, correctly identifying the problem.
But, for those of you who aren’t sure what is wrong with the tree above – look closely at the drip emitter….
The problem is that the emitter is too close to the trunk of the tree.
Initially, when trees are first planted, it is a good place for the drip emitter to be.  The roots are primarily near the trunk.
However, as a tree grows, so do its roots.  The single emitter next to the trunk of a mature tree, isn’t doing it any good.
The roots grow outward and their ends are concentrated where the branches end.
The reason for this is that when rain falls, the majority of it drips off the ends of branches – so that is where roots tend to grow out to.
So, if your tree and emitter(s) look like the photo above; how can you ‘fix’ it?
As your tree grows, you need to add more emitters, equally spaced around your tree.  They should be located where the tree canopy (branches) end. (I do recommend burying your drip line – it looks better 🙂
Below, is a photo of a large tree and I have drawn in recommended emitter placement…
You can see the emitters are widely spaced around the tree and are located where the tree canopy ends.  As your tree grows, you need to continue to move the emitters outward.
The Arizona Municipal Water Users Association has a great, free publication that guides homeowners through landscape watering, including recommended watering schedules….
The diagram above, from “Landscape Watering By the Numbers” shows recommended emitter placement along with how deeply trees should be watered.
It’s important to note that trees do not need to be watered as often as your other plants.  But, they do need to be watered more deeply – 3 feet.  
(Here is a link for how often to water your trees and other plants if you live in the greater Phoenix metro area).
**If you don’t have a separate irrigation line for your trees, you can periodically deep water your tree by turning your hose onto a slow trickle and let it slowly soak into the soil.  Move the hose until the entire outer canopy of your tree has been watered.  
 So, do you have this “landscape no-no” in your garden?  Don’t worry – now you know how to fix it 🙂

**Stay tuned for our next “landscape no-no” soon!** 
To receive your own copy of “Landscape Watering By the Numbers”
simply click the link above.  You can also view it online.  Note – this publication is written for residents of the greater Phoenix area, but the information is very helpful to anyone who lives in a hot and dry climate.