Perhaps you could move the containers to dappled shade under a tree. Really not sure the heat would do too much harm, but then I do not live in Texas.

I agree that giving them some shade could be helpful as well as watering well. My only real concern with those temps would be possibly fruit set trouble, BUT, they may be fine. It would probably be more helpful if a native Texan chipped in here, experienced with all of you guys' extreme heat.

Unfortunately, the containers are really big and heavy, so they are not very movable. Around 4:30, they are shaded from the afternoon sun by a tree's shadow. I hope that may help the plants.

I agree with Daninthedirt, the plants will be fine as long as they are watered. I've never had heat issues with growing in large containers and the high temps are pretty normal for this time of year. They will appreciate the afternoon shading. My tomatoes (pretty much all of my herbaceous plants) look wilty when the sun is beating on them but as soon as they get some shade they'll perk back up. That's normal in my garden anyway.

Insulating and shading the containers as already mentioned and mulching the very well helps too. If you have any access to some organic mulches - shredded leaves, hay bales, straw, etc. you can pile them up around the containers as well as topping the soil with mulch.

This is where drip irrigation systems on automatic timers come in real handy.

Dave

I'm pretty sure I remember that above 90* the blossoms drop. I would take a guess that if the maters were already formed, you might be OK keeping them shaded and watered

My tomatoes still set fruit when it hits 90, but the plants just get really wilted.

It is the nighttime temps that get tomatoes to stop setting. Once they get above 75 at night then close up shop. WE are supposed to get to 104 next week. SHEESH!. To early for me.

I've never been entirely clear on that, wantonomara. Clearly, when it gets hot, tomatoes stop fruiting.

Is the deal that temperatures below 75F are required for fruiting, such that after a hot day, they just fertilize at night if it's cool enough? I've heard of tomatoes stopping fruiting for desert area folks, where daytime temps are high, but nighttime temps are low. In that case, I guess high daytime temps simply incapacitate the pollen permanently.

It would be nice to get some good research references on this. Never seen them.

plants need a rest. That's the unscientific version. lol. I am a dilettante when it comes to the actual botanical processes and how they differ from night to day.

I think the question is whether tomato fruiting is a matter of whether it ever gets cool enough, or rather that it doesn't ever get too hot. Those are two very different situations. Where I am, when it gets hot in the daytime, it stays warm at night. But other locations may be different. Especially dryer locations, where it might get burning hot in the daytime, but might still get cool at night.

I can imagine that there are ways to cool off tomato blossoms for a few hours. Is that all it takes?

Hey desert folks, when your daytime temp is 100F, but at night it drops well below 75F, do your tomatoes fruit?

My friend in Tucson is having 108 weather right now and still has tomatoes going great. His lows are 65,... well yesterday his high 107 and low was 64. just checked. That nightly cool down must be great for a plant.

Well, in July, I still have tomatoes going great. I'm just not getting any new ones. The ones that fertilized in June are ripening great.

The question is a simple one. Do high daytime temps damage the pollen
and make it completely useless? Or do high daytime temps just prevent
pollination DURING THE HEAT, such that when it gets cool, the pollination can happen?

But if your Tucson friend is still getting pollination with daytime temps of 108F, then yes, it's the low temps at night that matter.

If I had a cluster of tomato flowers, I could mount a baggie around them with an ice cube at the bottom. It'll be nice and cool in that baggie for a whole night. Tomatoes in the morning. But humidity prevents pollination as well, and I suspect it would be pretty humid in that baggie. Am I forced to push an HVAC a/c duct up to my flowers if I want fertilization?

A little late to this party, but agree fruit set will slow in the heat, and humidity. Also, this year I pruned some of my interior leaves to keep the plants open where air can circulate. We get lots of heat, humidity, and rain here, and thick, dense, wet plants are a breeding ground for disease, and bugs. Also preventitive spraying with a fungicide will help too. We've been picking tomatoes here for three weeks. Septoria hit me early, but we're past that, and all looks good. 8" of rain in tha past 2 weeks.

Dan, I know you're just laying out a scenario, but if you really wanted to cool flower clusters with ice, use dry ice. The CO2 would not cause humidity (unless it affected the dew point in a VERY localized 6" radius lol,) and the plant would even appreciate the breath of fresh CO2. But... the cost would be... well you get the idea.

Yes, good point. Dry ice would be the way to go, I guess, though I'd worry about freezing the foliage. Not that I'm planning to do this, but sometimes understanding a problem is helped by coming up with a solution to it, no matter how wild and weird. If high daytime temps prevented pollination, even dry ice at night wouldn't work.

BTW, in my parts, fruit set on tomatoes doesn't "slow in the heat". It stops. BLAM. We're going to get 100+F temps next week, and the lows will be high 70Fs, when the RH will be 85%. No tomatoes gonna happen next week.

Glad you read my post and corrected me. I should have said, "It stops, BLAM." hahaha lol. My bad.

I googled this question of heat and tomato fruit setting yesterday and found an article by the University of Delaware coop ext. (Haven't been able to figure out how to post a link) Informative read.

Yea, in Central Texas we get the heat AND the humidity withOUT the RAIN. It really is a bum deal.

I corrected above post. We are getting the heat & humidity WITHOUT the rain.

In fact, I don't remember Central Texas temps topping 100F in May. Cool spring, and early summer inferno. That makes for a low quality tomato season, which usually can scrape by through June. The idea here is to have the plants mature long before the heat prevents fertilization.

Same in North Texas. Very cold April, maybe two weeks of decent temperatures, then an abnormally hot May. This is my first year growing tomatoes, so I never really payed attention to the temperature that much. Is it usually this way in terms of temperature each year?

I plant out in late February, and my plants are usually maturing in mid-April. This year, that maturation didn't happen until early May. Then you get new tomatoes late April through May and maybe June, and things shut off entirely in July.

In terms of productive tomato months, no big advantage down here compared to up north. Peppers and eggplants are another thing entirely.

We had 112º on May 27 (7 years ago today) in 2011. I was making a movie on an absolutely hideous day up Cisco Texas. You could not drink enough water. Thank god there was no humidity. In Austin , there was a high of 100º that day. It only got worse that year.

we had 96 today. don't ever remember that in may. it could be a portent of a dry summer here, and the corn and beans are barely up ...

Well they have come down a little on their projections. 101 is not 105 but still bad. We won't hit the triple digits till June. LOL. Did all you guys forget the misery of 2011? ... linda like forgetting the pain of childbirth. It was seared into my memory. May ended with a series of 100's in the Austin area. We were already having brush fires around us.

Yep. 2011 gave us in Central Texas NINETY days over 100F. That's about five times more then normal for the year. As I said, the art for tomatoes in these parts is to have a warm spring allowing early plantout that lets the plants mature, to give time for pollination and fruiting before the heat sets in. Worst possibility is a cool spring immediately followed by killer heat. In that situation, the plants are barely mature by the time they are prevented from pollinating.

Up north, the race is against frost. Down here, the race is against heat.