I live in Rosamond in the Antelope valley ..Aware of the hot dry conditions..Going to sound crazy..Last year i planted peppers inside a lrg brick i saw this on Pinterest and it grew amazing and i got quite a few peppers..

You should be able to find decent bagged products that contain peat, bark, perlite and maybe some compost. It looks like you could just add some perlite in with the stuff in your pic and you'd have a poor-man's 5-1-1.

Are you planning on nursing your tomato plants through summer into fall? Few if any types produce above 90 degree heat and can look really ragged.

THEEE most important thing for any container in a hot dry climate (note I'm from Vegas) is complete afternoon shade during summer. Even though a lot of plants say "Full Sun" or "6+ hours of sun", it doesn't apply to us. Two to four hours of morning sun then they have to be in complete shade from Noon or 1pm on no matter what kind of plant and no matter what kind of container. Else the soil in the pot just gets too warm and roots get cooked. People think watering more (2-3x/day) helps but it actually hastens the plant's demise.

Water from the top until some drains out.

Bark or straw mulch is a good idea.

Google "micronutients" and find a liquid fert like Foliage Pro that contains them all.

I think in hot and dry summer( no rain, low RH, like So. CA, in July) You have to water your plants more often and I don't think there is a shortcut for it. What you can do is try to pick a medium with more moisture retention and a location that limits direct sun to about 6 hours daily. Obviously bigger container is advantageous in storing more moisture , longer. I would also choose WHITE or light color plastic container ( as opposed to black) to reflect and radiate some of the heat away. I have the oposit situation here. So I choose black containers and I can get by with smaller containers.

Also try to mulch the top of your container with bark nuggets to minimize evaporation and getting the soil hot. In a plastic container, water/moisture is evaporated from the top surface and the foliage only.

I read about a method of gardening suite to hot, dry areas called keyhole gardening. Here is a website.

http://www.texascooppower.com/texas-stories/nature-outdoors/keyhole-gardening

Thanks very much. I used shade cloth to keep tomato plants alive through last summer in my raised bed, and one of the reasons I want to try containers is so I can move them to follow or avoid the sun as necessary. I also just discovered self-watering containers, so I'm looking into them now. Lots to think about!

I am a little south of you in north county San Diego. Last year was my first year with container vegetables. I have full sun and lots of drying wind all day long.

I had excellent results with summer squash. No matter what I do in the garden, squash wilts mid day. In the container garden there was no wilting and high production. Very good success with basil and broccoli. Bell peppers were good but some of the garden peppers did better. Same for tomatoes.

Bigger pots do better as they hold more water. i water about once a day.

The squash was in 20 gal pots which seems adequate. Some squash in #15 (12 gal) did ok. #15 for tomatoes seemed too small. 25 gal for tomatoes was ok but I want bigger. For smaller plants it is ok but I am trying 40 gal for bigger plants this year.

Basil did fine in 5 gal pots. However You can't leave for a day or two unwatered so bigger is better.

This year I am going to get saucers for watering if I have to leave them for a couple of days. Saucers for the 20 gal and up is more difficult I may try to make my own with concrete.

I like the Earth Gro ground cover bark at Home Depot. Batches vary a lot. Sometimes it is good, sometimes not so good.

My biggest mistake last year was not enough nitrogen. The bark eats it up.

I mix about eight parts bark, one peat, one Kellogs Amend (composted poultry manure, rice hulls, gypsum and etc.) and one part calcined clay (kitty litter) I add Vigoro citrus and avocado fert (has some micros and slow release nitrogen), gypsum,epsom salt and dolomite lime and a little Am nitrate to the upper half of the containers.

I use black nursery pots because they are the cheapest pots I can find. Twelve bucks for 25 gal and 22 bucks for a forty.

Zeuspaul

The best memories of gardening in Phoenix are of Armenian cucumbers. They seemed to thrive on the heat and sun. I should think they would thrive in containers.

I have alot of container plants and always use redwood bark mulch to keep them alive. I live near Sacramento and it is HOT in summers. With the bark, I can water just once a day.