Many cultivars of Japanese maples are quite heat tolerant and should do well in your zone 9. However, what they don't like is a combination of high heat and strong afternoon sun. If you can provide some sort of filtered or partial shade during the afternoons, that would be ideal. Strong sun can scorch the foliage and place unnecessary stress on the plant, especially those grown in containers.

As to selections, there's a lot to choose from :-) You are not really very limited by container growing except to match the size of the container to the size of the tree appropriately. And avoid those with variegated or very pale, light colored foliage (all the 'reticulated' types) which really require a shaded position all the time. A few varieties you could consider are:
'Fireglow'
'Kamagata'
'Shaina'
'Seiryu'
'Glowing Embers'
'Trompenburg'

I wouldn't recommend the cactus mix. JM's prefer acidic, well draining yet moisture retentive soils and you will need to replicate that with potting soil, keeping in mind the special requirements presented by container growth. A potting soil recommended for acid lovers like rhodies and azaleas is ideal. Look for Gardner & Bloome Acid Planting mix - it should be available at better nurseries in your area. I use it exclusively on all my containerized maples and it holds up well.

And you might want to check out the websites for Pacific Coast Maples, Mendocino Maples and Essence of the Tree. All are Japanese Maple specialty nurseries located in California and have some excellent info on growing them in your climate as well as growing them in containers.

Thank you for the valuable information.I have strong afternoon sun.I will need to build some sort of shade, possibly a pergola with a sunscreen.Jaime.

Having lived (and commerically grown japanese Maples) in Sanata Clara, I can tell you that we by far the best luck with acer palmatum 'Bloodgood' and if you want a smaller one, acer palmatum dissectum `Tamukeyama' would be a good choice.
I would suggest some FoxFarm japanese maple food. In our nursery we have great luck with it. Stay away from Garden&Bloom potting soil, it is a very bad mix for Maples. We graft about 200 Japanese maples each winter and we lost an entire crop to garden and never bloom.
Steven

Steven, I'd have to disagree - Gardner & Bloome acid planting mix is ideally formulated for containerized maples. It is sufficiently but not overly acidic, it has proper texture, is fast draining and it retains adequate moisture. If your crop failed, it was not because of the potting mix. I grow ALL my container maples in it and I've never lost a plant - they are healthy and grow well. And I've been using it for more than 10 years.

But it is not the only product available that will work. For maples in containers, one wants a coarse textured, freely draining mix with a high proportion of bark fines. And something that provides a proper pH. You can certainly mix up your own if you like and have the knowledge to do so. But the Gardner & Bloome product is a readily available and perfectly reasonable alternative - there is nothing inherent to the mix that would cause any problems for maples.

Actually, we (Graden&NeverBloom and I) DID have it tested.
It was the mix. I was not the only nursery that suffered as a result of it. It was not available at retail centers, it was only sold to nurseries. It came in a very large cardboard box on a wooden pallet. It was totaly worthless. Had the highest content of sawdust of any planting mix I have ever encountered.
Scared me away from ALL of the products from Kellog (the owner and manufacture of Garden&NeverBloom).
Steven

I don't know what you got but it wasn't G&B Acid Planting Mix. First, according to my Kellogg sales rep, this product is available only through retail nurseries - they do not wholesale it. Second, there isn't any sawdust in it. It is comprised of fir bark fines, humus, peat moss, sand, worm castings, bat guano and oyster shells. It offers nearly ideal soil characteristics for containerized maples, conifers and any acid lovers and comes highly recommended by scores of retail nurseries and container gardeners.

While you may have had a bad experience with a Kellogg product, I am skeptical it is the one I referred to and that I have used for dozens of containerized plants - conifers, maples and broadleaf evergreens - for many years without a single problem.