Here is a bunch of previous heat-tolerant discussions.

And here are tomato recommendations/methods from over on the Arizona Gardening forum here. Looks like proper planting times is the crucial factor.

Hope this helps.

Dave

Here is a link that might be useful: Heat tolerant tomato discussions

Porter will outsurvive any tomato in the heat and produce but is a bit bland in taste. You can't have everything. It's also very prolific which is a bonus.

zander, where in Arizona are you? I'm in Phx and am trying one called Super Sioux that is said to like hot dry conditions.

But no tomatoes really are going to produce in the heat. Here at zero elevation, I am going for short dates to maturity and let the beds rest through summer.

I'm interested in others comments. And although the link digdirt provided has lots of good info, new conversations can bring new enthusiasms.

@marymcp I live near Florence, but not in the town, so it's a little higher in elevation and can be a little cooler. I found Super Sioux in a search too and it sounds like it would do good. I found a variety called Thessaloniki though and I would like to try that out. Also, I'm going to be planting within a week or two, so it shouldn't be too bad in terms of heat, but I wanted to find a heat tolerant variety, so that just in case it gets real hot one week I wanted to make sure they would survive, which occasionally happens.

I'm in Pueblo, CO. We have two months straight with highs over 95 and my tomatoes were in direct sunlight from sunup to sundown. It's nothing like AZ, but it is still very arid and during the most brutal spells of 100+ days Super Sioux really did take the heat along with direct sunlight better than the other two dozen varieties I planted that year. At your elevation, you might also want to look at Cold Set, if your nights still get cold in the spring. It's not as tasty as Super Sioux, but it is very tolerant of both cold and heat.

You can always try those varieties supposedly bred for heat-tolerance. They all seem to have "sun" or "heat" or some similar "hot" element to their name - Heatmaster, Solar Fire, Sun Set, Solar King, etc.

With the possible exception of Florida 91 that Jay mentioned, I have found most of them to be quite tasteless and not worth the space.

You all are fortunate to have 2 growing seasons and such early planting allowances that I'd think it would be much easier than for most of us to push the early-planting envelope. Even if some early protection is needed. That way you'd beat the worst of the heat as long as you stick with short and/or mid-season varieties.

Dave

I'm in the hottest part of the San Fernando Valley and certain varieties definitely do better than others here. Kelloggs Breakfast, Persimmon, San Marzano and Aussie all do great in the heat. So do Arkansas Traveler and Homestead and they both produce mid-season.

Last year I grew several grafted plants to see how they would hold up in the heat. I cannot stress how pleased I was! We had four weeks of 100 degrees plus and most of the conventional plants, in spite of mulch and shade cloth couldn't hold up to it. The grafts, on the other hand did beautifully and without being watered for four weeks! I encourage you to try some.

<...last year i grew several grafted plants to see how they would hold up in the heat....>

What does that mean exactly?....grafted plants. Could you provide more detail about that phrase? Thanks.

Here Mary - lots of discussions about grafted tomato plants. They are available from many different sources.

Dave

Here is a link that might be useful: grafted tomato plants discussions

Mary, grafted tomatoes are heirloom varieties (and some hybrids) grafted (attached) onto very strong tomato root stock. The root stock is incredibly resitant to disease and is less sensitive to cold and hot temperatures. It allows us to grow plants, including some varieties that are typically difficult to grow, without some of the usual problems. There's almost no soil borne disease and since the roots get much larger and stronger than conventional tomato plants, they grow into healthier plants that produce a higher yield of fruit and for a longer time. The grafted plants cost more than conventional tomato seedlings but are so worth it! Planting them is a little different, too. I'd be happy to tell you more about that if you decide to try some.
Laura

There are a few different ways to look at heat affect to tomato plants. Some varieties just have such a prolific vegetative growth (more respiratory water loss) that they will be naturally stressed more by heat; others drop blossoms at higher temps. Even though an improved root structure will help, the best thing you can do during hot weather is provide more water. Shade will also go a long way in helping. I haven't seen any benefit of using grafted plants in PA but I'll acknowledge those graft rootstocks (I used Maxifort) develop a massive root system.

Varieties that develop sticky stamens that will drop blossoms should be avoided. I know of very few heirloom varieties that handle heat well except the golf ball sized variety, Pusa Ruby, from India. If you google that variety you find that much tomato research in India includes it. Orange Blossom has always had a good reputation but it isn't a great eating tomato.

My suggestion would be to use any of the suggested varieties, but keep them well watered during hotter weather. I find that all will tolerate spikes in temperature and resume fruiting as soon as daytime high temps return to 80's (60's at night).

What are sticky stamens, and how are they related to blossom drop?

i stick with juliet, yellow pear and early girl i grow german queen and black prince for flavor too but by 4th of july they're done the juliets and pears slow down in the heat i prune them back and they fire right back up in september and produce till january frost had on plant go 2 years then it dies of in april

I'm curious about shading tomato plants in the heat. When I first started gardening it was in Tucson. I remember back then that some people had good results using shade cloth over their veggie beds. Here in GA there is a farm not far from us where they grow some tomatoes under the outdoor eaves of their barn, in the shade. They say the tomatoes do really well there in the heat. I haven't tried shading yet, but if you can afford it or have a good location, it might be worth trying with a plant or two.

Sorry, Missingtheob.., that I didn't explain more but I should have probably put "Sticky stamen" in quotes because it is a generic term for a theory that the male flower parts get sticky in hotter temperatures and do not release pollen. Naturally, if the flower ovary isn't polinated there is no initiation of fruit and the flower just wilts and drops. But what should be emphasized is that there are many varieties, mostly hybrids, that are more reliable in setting fruit at both higher and lower temperatures. Some heirloom varieties seem to stop setting fruit when high temperatures even reach to mid 80's F.

Thank you for the answer, bmoser. Interesting theory. I suppose it has to be either the stamens or the female parts to blame for not setting in hot weather. (Unless, as all-too-often here, it's Late Blight.)

mto

Like so much of the US, we got unusually hot (many 90 & several 100 degree temps.) and dry weather last summer. Of 20 or so varieties, Porter was the only one that kept producing right through the heat waves, so was my most productive (by total fruit weight) by far. I agree with everything else that grow4free mentioned above as well, including the flavor.

I also grew Sioux, which has a more zippy flavor, but did have slow-downs in production.

I have been growing (or attempting to grow) tomatoes in Tucson for many years now. My philosophy with tomatoes is grow sandwich sized tomatoes of good taste and heavy production on disease/heat resistant plants. I have tried Super Souix, Porter, and others with minimal success. The problem tends to be that the plants get very big without much fruit set before or after the main heat of the season.

My experience has been that the bulk of my food production from tomatoes has been from varieties that are referred to as semi-determinate (tomato varieties that are determinate in size, but indeterminate in fruit production). The best tomato I have grown in this class has been the F1 Celebrity. It is very easy to come by and does very well with only a little west-side shade after the month of May. 6-12 of these plants will feed a family of 4-6 with tomato sandwiches all through the summer. (As a note I do not use shade cloth and plant my tomatoes FAR from structures such as houses or walls that radiate heat at night).

Many heirloom and other open pollinated varieties of tomatoes can produce very nice foliage here in the desert but they often fail to produce any significant amount of fruit. After trialing multiple open-pollinated tomato varieties each year, the best open-pollinated variety I have ever grown that tolerates the heat has been Siletz (see the link below). This variety is parthenocarpic, so it will produce virgin fruit through the summer, then, from my experience, you will be lucky if you can get some seeds from the plant in the fall. (= Neptune is also another good variety but it is a classic determinate, meaning it produces only one crop before its demise.

No matter what tomato I grow, the biggest key to growing tomatoes in a desert climate is to put them in the ground or have some kind of insulated container with a water reservoir. Once the plants are established you must wean yourself from the tendency to water every day. Gardeners who water (at most) once every 3 days have much more success than those who water every day. Though this is initially counter-intuitive, flood irrigating or watering for 2+ hours on a drip hose every 3 days enables the roots of the tomatoes to develop 18-24 inches below the surface of the ground where they are well insulated from the scorching summer heat. The main benefit from watering occasionally comes in less plant stress and consequently, much less disease and pest problems. If you are new to this area you might also note some of the considerations to growing tomatoes in the following blog post: http://scientificgardener.blogspot.com/2012/01/few-tips-for-growing-tomatoes-tucson.html

Here is a link that might be useful: Siletz tomato trial

I've had a lot of the same issues as Tuscon. Lots of growth and few tomatoes. I'm trying yet again this year. I put the Epsom salt, aspirin, and humic acid in a raised bed with good soil. I have the shade cloth ready when it gets time. We will see.

Any other heat Advice is welcome or any other innovations to share. How about hand pollinating somehow during the summer months. I was thinking of keeping one plant in the house so it's cooler and using its pollen for outside tomatoes. Would that work and how to do it?

What other parthenocarpic and tasty varieties are out there?

What other parthenocarpic and tasty varieties are out there?

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LEGEND: It is also developed by The Oregon State University, as Siletz.

Google it.