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The Impact of Microclimates...block walls in Phoenix and the last Peach orchards in Paris

Over the last 21 years that I've lived in Phoenix, I've realized we do some strange things here in the desert, mostly because we don't understand our climate.  And we don't understand climate because we have modern conveniences, like air-conditioning and as much water as we want right out of the tap.  This mitigates the effect of some of the design "Don'ts" that are so common here.

Like block walls surrounding our yards...

Like MY block wall.  The block wall that I spent thousands of dollars on.  Sure, it's pretty, but what I didn't realize is that I was that I was basically increasing the heat in my backyard by building it.


Block walls:

--block breezes and airflow

--trap warm air in the yard

--store heat in their thermal mass and release it during the night when temperatures drop, adding to the Urban Heat Island effect

--If the wall is a light color, it can bounce reflected light around in your yard and burn nearby plants.

Am I anti-fence or anti-wall?  Nope.  But if I had it to do all over again, knowing what I know now, I'd do things differently.

Like what?

I'd install an open fence - something in wood, or metal - even chain-link.  Then I'd plant thorny plants on the outside in the alley (natural burglar protection) and vining plants ON the fence.  Inside the fence, I'd plant some screening shrubs and some overstory trees that some of the taller vines could grow up into.  This would give me some natural AC as the plants would transpire and the breezes would flow through.

So a lot of people don't think that microclimates make all that much difference.  How much hotter could it be near a wall with a lot of thermal mass?  Well... it can get hot enough so they can grow peaches in Paris - not an area known for peach growing! 

Check out this beautiful blog post at Messy Nessy Chic.  She chronicles the history of peach growing within the city of Paris - a booming business back in the 17th century.  The peaches produced were coveted by royalty as far away as Russia.

How'd they do it?  They manipulated their microclimate.

All those things that make block walls a problem here in the hot desert, make them ideal for heating up a cool climate.  Here are a couple of quotes from the blog:

"The peculiar architecture, known as “Murs à pêches”, wall for peaches, served to protect peach trees planted near the walls and adapt them to a much colder environment than the fruit is typically used to."

"The 3 meter high walls were more than half a meter thick and coated in locally sourced limestone plaster, giving them a high thermal inertia and the ability to store heat. Their intentional north-south orientation allowed solar energy to be stored in the walls during the day and transmitted to the trees during the night, preventing them from freezing and accelerating the ripening process. Within these walled orchards, temperatures were typically 8 to 12 °C higher than outside." 

Let's revisit that last part "temperatures were typically 8 to 12 °C higher than outside".

That's 14 to 22° F higher!  And Paris is in a "gentle" climate zone.  They don't get up into the 100's for months on end like we do.  So I can only imagine what the temperatures are like on my south and west facing walls when it's 112° F. 

The upshot of all this?  Microclimates matter.  A lot. 

Visit the blog for more lovely shots of the Peach orchards of Paris.

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I wonder if I could use an Ocotillo  living fence covered in Grapes to protect my solar powered well setup. That would be pretty cool down there in vineyard country.

It's worth a shot - ultimately we are all just experimenting.  You might invent a new guild, even.

What came to mind when I thought about it is "I wonder how similar the water needs for ocotillo and grapes are?"  Grapes can take it pretty dry - I'm wondering if ocotillos would consider the amount of water grapes need as an overabundance, though?  Anyone have thoughts on this?

in vegas, oleanders seem to be the cheapest and most dense and reliable evergreen living barriers.One could simply walk by some neighbor's oleander wall and trim off hundreds of cuttings.

fences that actually grow. Has the advantage of needing little water, but has the disadvantage of needing too much upkeep as it grows way  too fast even with little water!

Here too.  A lot of people dislike oleanders but they perform quite a few functions.  And contrary to popular belief, you can compost them and the toxic qualities of the plant are broken down. 

See this study by UC-Davis:

oleanders are tough as nails. And  just realized--- there are currently only three evergreens i know capable of growing vigorously(unsheltered outdoors year round) in both   las vegas  and  tropical manila: the oleander, the calamondin, and the aloe vera. Some cacti and euphorbs do well too in manila, but grow way too slow, and/or may succumb to weeks of raining/high humidity typical of   the tropics.

btw,  most, or probably all, organic toxins are biodegradable.

 oleander toxicity also make it  an excellent and economical choice  when considering fencing off acreage in desert conditions. Sources for free cuttings are limitless, and is  a relatively fast grower, drought resistant, and unpalatable to wabbits, equine, ovids, and bovids.

Yep - it would make sense that the organic toxins are biodegradable otherwise nothing would be growing today! 

I had already thought of trying out grapes on the native Mesquite. They can handle different moisture levels + they're nitrogen fixers. There are acres & acres of overgrazed land down there full of the shrubby trees.

I think that would work out pretty well!  Please keep track of your experiments so we can all benefit from what worked and what didn't.  That way we don't all keep re-inventing the wheel over and over again.  =)

My mother's grape vine grows over her mesquite... looks like a grape tree!

Cool! Do you know how she takes care of it? I'm curious about fertilizing & stuff. I've never grown a grape vine.

I have a grape vine too. I just water it occasionally. Sometimes I sprinkle chicken manure at the base. It's pretty easy- needs sun. I believe she just uses compost. She has her's in a shadier spot than mine, but they do like sun.

We're going to try it out on a neighbors tree since our land has zero Mesquite. He's been fascinated with our efforts & wants to do something with the tree on his property. He just wanted to try to shape it, but he will love the grape idea.


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