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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.

Have you ever had a ‘substitute’ teacher?  As most of you know, a substitute teacher doesn’t do things the same way our regular teacher does.

A few years ago, I was asked to step in as a ‘substitute’ for my father-in-law’s landscape.

Meticulously pruned desert ruellia (Ruellia peninsularis)
 
My father-in-law had always been a meticulous gardener and took a lot of pride in his landscape.
Have you ever seen rounder shrubs?
 
A few years earlier, I had designed the landscape around his new home and tried to convince him to allow his plants to grow into their natural shapes.  But as you can see from the photo above, he didn’t follow my advice.
 
He eventually took out his backyard grass and replaced it with artificial turf and whenever flowers or leaves would fall on the grass, he would vacuum them up – I’m not kidding.
 
We would often joke with each other about our very different styles of gardening – especially when he would come over to my house for a visit and see my plants growing “wild and free” as he would say.  
 
But despite our differences, we shared the same love for plants and the garden.
 
Unfortunately, his gardening days were numbered and he asked me to come over and help him with the gardening tasks that he could no longer do.
 
My father-in-law was diagnosed with ALS (Lou Gehrig’s disease) in October 2010 and it progressed very rapidly.
 
So, I became his ‘substitute gardener’ and I was happy to be able to help out so that he could still enjoy the beauty of his garden, even if he could not care for it himself.
 
 
In early August of 2011, I lightly pruned back his gold lantana.  At this point, my father-in-law spent most of his time indoors sitting down. But, as I was pruning, I saw him slowly make his way out, with his walker, so he could watch me prune his plants.
 
At this point, he could no longer talk due to ALS and I’m certain that if he could have spoken, he might have asked me to make the lantana ’rounder’.
 
After this light pruning, the lantana would grow back to its original size before stopping during winter.  If they had not been pruned, they would have look quite overgrown for my father-in-law’s taste.
Light pruning involves removing 1/3 or less.  The timing of this light pruning is crucial – prune too late and your plants will be extra susceptible to damage from frost.  Don’t prune after early August in zone 9 (July in zone 8) gardens. Pruning in fall should not be done for this very reason. 
 
 
Another part of the garden that my father-in-law took a lot of pride in was his flowering annuals.  Every year, he would plant the same red geraniums and white-flowering bacopa in winter.  Once spring rolled around, he would plant red and white vinca. He never deviated by trying out newer colors or varieties.
 
I found myself taking over this job as well and when I came home and see all there was to do in my neglected garden – I didn’t mind.  It felt so good to be able to control how his garden looked because ALS had taken control of everything else.
 
My father-in-law died in September 2011, just 11 months after being diagnosed with ALS.  
 
It’s been almost 3 years since he passed away, but whenever August comes around and I find myself lightly pruning back my gold lantana – I enjoy the memory of one our last moments together in the garden as I pruned his lantana.

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