There is such a thing as a "microclimate". The presence of plants in a yard and moderate shading provided by trees can significantly alter the temperature and humidity of a yard space. The presence of a pond will no doubt increase general humidity, if the yard is not all open and there's wind-break of some sort.

Many Japanese plants will indeed be challenging to thrive in the hot dry climate and temperature extremes of Arizona.
(bamboo will have no problem growing though, provided it is well watered)

I really do not think Bougainvillea would make a substitute for Azalea. My favorite part of a Japanese garden is the moss, that will be hard. Maybe in the shade. Your garden is probably going to take a large amount of care in that hot dry climate.

What are the parts of a Japanese garden which make you most attracted to it?

Microclimates are very important here. Much more so than any place I've lived, NY, FL, TX, AK, CA. Unfortunately a pond by itself doesn't really do enough to create a meaningful microclimate. Right next to a water fall does though. Mostly we use shade as the biggest microclimate tool.

Unfortunately many kinds of bamboo struggle. They normally survive given enough water but leaves turn brown. Oldhamii does OK in good conditions. Bamboo Ranch in Tucson grows over a 100 kinds but they're a lot cooler, 99-101F avg high in summer while we're 104-107F.

If not Bougainvillea then what? It's not a perfect substitute, just as close as I've been able to think of. Pruning will be key though and of course it can't be close to viewers.

Moss is a curious plant here. It actually does grow in surprising abundance. Also algae. It's not a great moss, very small, thin layer. It does need shade and overhead watering. Here is some growing on stack of clay brick, horizontal. This was last Sept so still pretty hot. West facing so full sun from say 12-4pm. This grew after some rain but this gets no irrigation. Surprised me.
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The big difference may be humidity, we get more, 20-40% range, in the fall than spring. Maybe pH? Don't know.

The hillside slopes away from the sun but isn't steep enough to shade the soil. But plants and rocks will cast a longer shadow on the soil.

I think the key for any moss hope will be overhead watering and not disturbing the soil when weeding, pruning and walking. I've buried wood steps in the hillside for staying off most of the soil. Beyond that I'll just have to try whatever I can.

The parts of Japanese, and Chinese for that matter gardens, that interest me in order:

1. Pruned pine trees. I grew up on a fruit farm and learned tree pruning early, but I never learned about pines. I want to see how they react and how they can be controlled.

2. The concept of controlling different views. I've always looked at gardens as art, controlling the view though is new to me and interesting.

3. Using fewer kinds of plants. I've always been a plant collector, trying to jam as many kinds as I could into a space. That was fun, but creating a garden with only a few kinds of plants seems more of a challenge which I like. However the concept of jamming different kinds of gardens, forest, mountain, plains, etc., is kind of the same thing. So still trying to put a lot in a small space. Living in the desert helps me here. The Japanese garden will be almost surrounded by desert garden. The transition I think is interesting. Also, the contrast I hope will help the Japanese areas look more lush. Next a garden in Portland OR it isn't, but next to desert maybe relatively lush.

4. Spend more time in the garden. The current garden I made is desert. It's nice but almost nothing to do. I like working in a garden more than just sitting in a garden. I like weeding, pruning, etc.

5. The challenge of having such a garden in Phoenix. Finding plants that work, creating microclimates for that to happen is fun for me. Like a puzzle. Lots to learn about.

6. How rocks are used. I've built many ponds using lots of rocks but never really thought much about it. Looking at rocks differently now.

7. Use of roof tiles for paths, etc. I'd been doing that for awhile when I found out Japanese had been doing the same thing for a long time. Made me feel like I had a connection to gardeners of hundreds of years ago. Like the way I've come to create gardens is the same way they did. Reuse of what's available.

I probably won't be using any lanterns. No raked stone areas, basins, arched bridge, Japanese style fence or other structures or red paint.

Thanks for your time.

hello waterwise_guy,

I have experience with designing and building asian style gardens in Phoenix, but now live in northern Arizona where it is much easier to accomplish. Since you don't want a raked sand (Karisansui) style garden, you absolutely must create some shade either by using the canopy of existing trees or getting some mature ones planted. It would be nice to see a picture of your site to see what conditions you are dealing with.

With no asian "accessories" such as lantern, statuary, bridge, raked sand, etc. you will have to rely on plant material and boulder placement. Bamboo is an icon and so is a must. Giant timber may be too tall for your garden, golden bamboo does well with sufficient water and can be contained with rhizome barriers if needed. A pond should be included, especially to counter the hot climate and give humidity if in the right spot. Since Japanese Maples are out of the question (they will burn up with the first hot dry wind) trees that evoke the asian feeling will be difficult so I would use what they have a the Friendship Garden.

For boulders, I have found that surface select native boulders that have character and sometimes lichens are the best. Choose some that mimic an animals head if you can find one. Also, moss rock is great for flagstones pathways.

For plants, instead of using Japanese Garden Juniper which wont tolerate the heat, consider using Dwarf Myoporum. To mimic moss, use Angelita Daisy or Dalea capitata.

Water can be symbolized using river rock or pea gravel as was done at the Friendship Garden where they used it to simulate a beach effect surrounding the water.

Bamboo fencing can be purchased for a background screen or to contain the garden.

Once you have the right elements to work with, then its just your own creativity and design skills to put it together.

I have written a few blog posts about asian style gardens you may want to check out.

http://sedonalandscapedesign.com/asian-gardens/

Thanks. I've having trouble posting pictures with the new software and also having posts disappear. I've lost interest in trying to figure it out.

The garden has already been planted with the plants listed in my first post. My moss solution has been Dichondra micrantha.. The pond is also in, although water hasn't been added yet. Needed the dirt to create a hillside.

I also originally assumed lots of shade would be needed. Now that I've nailed down the plant selection it turns out even full sun would be OK. However there will be increasing shade as the years pass from adjacent existing trees, the new pines and the bamboo. Shade is still desirable for people, but most of the plants are OK with sun. I do have at least one part that has more shade. So this will fit a stroll garden, some sunny parts, some shaded parts.

I stayed as far away from ubiquitous surface select rocks as possible. The shape is wrong imo for a Japanese garden. They are soooo common here in desert landscapes I think they would counter my goals.

you can send them directly to my email rather than trying to "post" something via Houzz. John@jsllandscape.com

I watched part of your video. Very nice. But I'm trying to avoid standard western Japanese garden tropes. For example, I don't think all bamboo fences make a garden a Japanese garden. It's not the material, it's how the material is used. The craftsmanship. Buying a fence panel nail gunned together in China is more of a western thing. Perfectly fine, but not what I'm trying for.