Good questions. I'll start right out by saying that your first frost is probably in October, so you don't have enough time to get a tomato crop this year, unless you're considering protection. Tomatoes are completely frost intolerant. Your sun intensity is no different that that anywhere in the south, including the Central Valley, where tomato growing is widespread, so I can't imagine that you'll have a problem. Though seedlings will be more fragile in that regard. Also depends on the quality of the irrigation. If we're talking about low humidity, tomatoes actually kinda like that. Definitely an advantage with regard to fungal infections. But evaporation will be more of a threat, so good mulching is important.

Other people can comment with more experience, but tomatoes have a wide and shallow root system, so drip irrigation takes some effort to get right.

I'm in L.A. and would recommend some shade. 30% shade cloth should work well. If you checkout the big growers in like Fallbrook, they'll have shade cloth on their hoops in the summer. High temps are a problem for fruit set. I tend to start my tomatoes as early as possible and get them in by Feb. You'll have a harder time starting early because you get a lot colder. Short season toms started early can be pretty productive because you get your production done before the heat kicks in.

Be careful about too much amendments. Send a soils test off to UMass. You don't need more than 10% organic matter. Any more than. That and you are going to be polluting. Be careful about phosphorus. Manures have a lot of it and so do suburban soils, too much typically. Only add what you need.

Shade cloth isn't really going to affect flower temperature. The air temperature is what counts. Most tomato flowers are naturally shaded by some foliage anyway. Shadecloth is essential for reducing greenhouse temperatures, but it isn't used that much commercially in the field. But if tomatoes have enough water, they can stand high, hot, and full sun pretty well.

Nil13, my house does not have lawns so I don’t have enough compost to fill a raised bed. So my plan is build up the raised bed via the “lasagna method” using bale straws as brown and horse feed as green. I can get those from a local farm feed store. Then top it off with cow manure & use more straws as mulch.

The other part related to shade requirement is what materials do I build the bed with? I’ve thought about building it with cinder blocks but then how do I attach posts for shades? So maybe going back to untreated wood and I can just add 2X4s posts for shade.

Here in CA shade cloth is used to keep the skin thin and in the case of the hoops, as a wind break.

The lasagna method is way too much organic matter the layering is going to create perched water tables and uneven drainage. Raised beds should be filled with a sandy loan with between 5-10% organic matter.

Modern pressure treated wood is fine to build the raised beds. They don't use the chromium arsenic treatment anymore.

Do you have a hardpan layer or something that necessitates a raised bed? If it isn't necessary, I would skip the raised bed and plant in the ground.

We have found that when our daytime temperatures exceed 80℉ for a few hours the fruit will not set. We have not found any shade that will help.

No shade cloth doesn't help with temps and fruit set. You need the varieties that are heat tolerant to try to deal with that. But yeah, that's why even though we have a 11 month growing season I prefer shorter season toms so they are done by June.

Although I do want to try this stuff. White on one side black on the other.

http://www.teksupply.com/contractor/supplies/prod1;ts_shade_houses_material;pg111964.html

Look for guidance at your nearest branch office of the USDA Cooperative Extension Service. Or the Extension web site. Fruit and vegetable production is big in your State so CA Extension has lots of information including that which is intended for home gardeners.

Still wondering why you're assuming you need shadecloth. Too much shade will interfere with growth and production. I'd try it without shadecloth, and see if the plants are stressed. If they are, you can throw some shadecloth on top. I get violent amounts of sunlight here in Texas, and I've never needed shadecloth for tomatoes. Just a fact that more shaded beds produce less. But it is necessary to keep them well irrigated. Again, tomato foliage will prove shade to most of the fruit, so you have to establish why you need to shade the foliage.

I've been growing tomatoes for 25 years in SoCal and I don't need 100% of the light for maximum production and I get better tomatoes with shade cloth. Pretty straight forward plus there is supporting University research. And like I already said, the commercial growers here all use shade cloth.

Another concern in my area is strong winds. Sometimes the wind gust is so strong the windows rattle. I see some street trees tilted one way because of winds while they were young trees. So maybe I’ll need to put shade clothes on the raised bed, if nothing else it will act as wind breaks to protect my plants.

To locate your county's University of California Extension Service office, use this interactive map -

http://npic.orst.edu/pest/countyext.htm

Once there, click of California, then locate your county in the list for contact info.

The windbreak cloth would be on the side. And make sure you have strong supports, like 4x4s. I live on a hill at the mouth of a valley, so I am familiar with high winds. People underestimate wind load all the time.

I'm in a BSk climate with extra-hot/dry summers and cold to extra-cold winters at over 2k' elevation. The humidity has been particularly low in the summer, this year (between 10 to 20% most days, until recently), although it's usually fairly low (but it's been rising a bit, lately, as of a few days ago or so). Our hot period seems to have ended somewhere around today (the daily high was a cool 88° F. today, and the 10-day forecast is mostly not hotter than that). Before that it was about 100° F. for the daily high every day for a really long time (give or take about six degrees). I'm not sure how that compares to your area, but your 10-day forecast right now is warmer. It looks like you have somewhat higher elevation.

Anyway, I'd recommend checking out the following tomatoes (most of which I grew this year with black plastic—which seemed to be a disadvantage for many other varieties I grew, except early in the season, since it made the soil so hot that the leaves turned upside down on many kinds); the ones that follow among those I grew this year did pretty well in the black plastic, though:

* Brandy Boy (large; early; prolific; tasty; heat-tolerant)

* Burpee Gloriana (really good, zesty flavor; productive; vigorous; decent fruit-size; my favorite Earliana-type out of the ones I've tried; it does crack, though and it's not as early as Burpee Sunnybrook Earliana for me, but definitely one I want to grow next year)

* Frosty F. House (quite early; decent taste; keeps producing and growing; heat-tolerant)

* Matina (if you're really going to water it like that; it gets a huge plant, but I think it gets a lot more fruit if watered well; small to medium small fruits; tangy; early; potentially prolific; didn't grow this year)

* Coldset (if you don't mind the mild flavor; it begins as a compact plant; prolific; large fruit; heat-tolerant; the leaves really shade the fruit a lot)

* Sausage (if you don't mind the mild flavor; productive and very heat-tolerant, both air and soil heat)

* Mountain Princess (small-ish plant; decent all-around tomato; heat-tolerant; early-ish)

* New Yorker V (similar to Mountain Princess with a smaller plant; I've heard that this is related to Coldset, but they're very different tomatoes, in my garden)

* Sweet Orange Cherry (big plant; heat-tolerant; quite early; prolific; tasty; yellow; cherry; produces all season, and more so as the season progresses; didn't grow this year)

* Early Girl F1 (decent all-around plant; can be very prolific; it varies a lot depending on how or where it's grown; heat-tolerant; didn't grow this year)

* Celebrity F1 (didn't have much flavor for me; I'd recommend Brandy Boy over it for sure, though; didn't grow this year)

The ones I didn't grow this year were without black plastic when I grew them.

If tomatoes are anything like peppers in this way, I would also recommend mulching them for a desert-type area. We tried a bark mulch on some Sweet Banana peppers, this year, and it made an enormous difference! I think they might be doing better than the container peppers, even (whereas without the mulch, in the ground, our peppers have been kind of small, late and stunted, in recent years).

Anyway, mulch is probably better at moderating the temperature than something like black plastic (which might make it too hot in the hotter temperatures), and probably holds moisture in reasonably (especially if you have wind, which can blow under the plastic where the plant holes are). It probably lets more oxygen to the roots than black plastic, too (but that's just a guess).

But yeah, I haven't tried mulching tomatoes. I'm just guessing it'll help. I'd like to try it out on watermelon, and other melons, too.

If you can't mulch, you might try shading the soil/roots, without shading the foliage too much.

When the humidity is low, showering the plants (with the shower settings on a hose nozzle) seems to help the plants grow faster and healthier, with fewer pests. Some varieties like lots of water and some like drought, though. But if you're already using drip irrigation, showering the plants might be overkill.

I also suggest you save your own seeds. That seems to help the plants to do better.

Varieties like Mountain Princess and New Yorker V seemed to have smaller fruit with the black plastic than in previous years (just one year for New Yorker V) without. Although I still like and recommend these two, they didn't do the best with the soil heat (they didn't do terribly, though).

Different kinds of light seem to have vastly different effects on plants. I mean, it can seem super bright and hot one month, and the plants can be struggling in it, getting sunscald and burned leaves left and right, and another month they seem to love it with seemingly the same level of light and the same temperatures. Maybe it has more to do with air moisture than light, though (but it is the light that does the damage, whether or not the moisture has influence). The amounts of total light may not be terribly different, but something still seems different about the sun's effects. But yeah, I can tell something is different about the sun and the way it feels, even though the temperatures and brightness may be the same during both months.

I don't find it hard to imagine that what works in a certain area in Texas might not work in a certain area in California, and vice versa.

I'd recommend trying shade cloth on some plants and not others. Then you'll have a better idea.

Does the UV index affect plants? At higher altitudes the UV index may be higher.

Edit to add; Some PWS also report "solar radiation". Does this affect plants? Is solar radiation different at higher altitudes?

Not a direct experiment but I think it’s applicable. I put a container crepe Myrtle on east side of house so it gets sun *only* from 6am to noon. Now we all know Crepe Myrtle loves sun, but still some leaves were fried to a crisp. I now have a new found respect for the high desert sun.

I'm not sure how hot it gets where you live, but for me it's been 90s and 100s for the past few months. I live in very Northern California. The sunlight is very strong and my tomatoes get sun all day until around 5pm or so depending on month, then part of the raised bed gets shaded from an oak tree as the sun goes behind it to set in the west.

Provided they get enough water, I haven't had any problems. I have Burpee's Bushsteak tomatoes and I don't remember the other variety's name, San-something. Last year, I think it was hotter and we started the tomatoes late so I had a heck of a time keeping the seedlings alive, especially after transplanting to the ground. Then when they took off, the weather started cooling into fall. They lasted into November for me, actually, but none ripened outside and they'd gotten late blight I think. I did try to ripen the oldest and biggest ones inside, but it was hit-and-miss. I was so disappointed.

This year, I started the Burpee seedlings in February and kept them alive until I planted them in bigger pots while I waited for it to warm up enough outside. I kept the seedlings in my window. I planted the variety I got from Urban Farmer online in DIY self-watering water bottle containers in April, and transplanted the seedlings in May. Those ones are much further behind and have only recently started growing tomatoes due to the heat. The key for me is starting the seeds early enough that they have time to establish and grow enough to be able to withstand heat and strong sun, but not so early that it's too cold for them to survive outside. Likewise, don't start them so late that they don't have time to establish, strengthen, and eventually ripen before cold weather hits!

I actually have only had a few tomatoes ripen on the vine so far. I have tons that are still green; I've read it's likely due to the heat, as they don't really ripen in high temps like 90+.

I'm way too poor to afford a good watering system and shade cloths, so I can't give any advice besides that drip irrigation is awesome. I have one 20-foot, cheap $20 soaker hose that drips and it worked great last year. This year, I'm using the entire raised bed, so that hose isn't long enough, unfortunately. I just go in with a hose and nozzle on the shower setting and water what isn't reached. I did try to poke holes in an old regular hose that couldn't be used anymore as a DIY soaker hose, but...it's not ideal by any means. Perhaps if I had shade cloth, the tomatoes would ripen faster.

I don't think you'll have enough time to get a crop in, but I'm really not sure. Is it consistently in the 70s to 80s from now until to December or so where you are?

As far as wind: it was really windy last fall, so much so that in October, we had a wind storm that sparked a fire several miles away in the night and kept spreading it right over a mountain towards us and we were evacuated at 3am. When we finally returned about 3 days later, my tomatoes were wind-tattered, abused, and thirsty, but alive and fine. One of the tomato cages had been dislodged from the soil, so the cage and tomato plant were leaning forward/crooked, but it wasn't a problem. I removed most of the torn up leaves (there were plenty of leaves left after). I think that, provided you have a sturdy enough support, your tomatoes would be fine. Seedlings and young plants would certainly be a concern; if you notice the plants are struggling, then yeah, put up some sort of cover or protection.