Just be sure there are planty of good green leaves - that's where the nourishment for the ripening fruit comes from. Sometimes in hot weather, the leaves on the bottom of the plant tend to yellow earlier than they would, so it's important to keep some growing points.

Good gardening! Enjoy those tomatoes :-)

Tomatoes and the squashes do not set fruit when the temp is above 90-95 for extended periods. The reason is the pollen becomes gooey/sticky and can not be transferred to the pistol. When the temp get below 90 fruit set will resume. Plants that tall suggests heavy use of fertilizers. Evaluate your use and adjust to reasonable rates.

Thanks for response . much appreciated.
CDGTXS

''Tomatoes and the squashes do not set fruit when the temp is above 90-95 for extended periods. ''

This is a commonly repeated generalization which is not accurate everywhere, because I get tomatoes all summer long even in temps of 105+, as I have written here for years. I WISH everyone would stop repeating it as if it were a scientific fact!!! (That, and the "fact" that lemmings commit suicide, LOL)

I believe the actual truth MAY be that they have a hard time setting fruit when there are both high temps AND high humidity, but that is just my theory based on seeing the generalization repeated over and over and over, and that most "gardening experts" come from the East Coast, where Heat = Humidity. I think it would be fantastic if someone conducted actual experiments about tomatoes setting fruit, and compared the results from high humidity places to low humidity places, with the same temps.

But for everyone who lives in low humidity areas:

DON'T believe that nobody can grow tomatoes in summer heat, because some areas can, and I have photos of my September harvests to prove it! (And the lemming thing was a fabrication by Walt Disney, BTW)

Carla in Sac

Here in Southern CA, we have very dry heat with 100+ degree weather through the summer. The tomatoes and squash will still produce if conditions are right. My mother lives about 30 miles inland of the San Diego area and when she was growing squash and tomatoes in the heat, she had so many of them, she didn't know what to do with them all.

My tomatoes are setting fruit and it's been really hot here (90-105) since I planted them. They did drop some blossoms when it got 105 for a few days though but that could have also been my fault. I don't know much of what I am doing yet and neglected fertilizing them.

My squash is only just starting to bloom.

Carla, mine are shutting down, even the reliable old standby Stupice. Except for a day or two here and there, it has been 95+ since May 7. Blossoms just shrivel up and die. I'm going to hold off pulling them for a little while longer, but the only thing still going strong is Gardener's Delight, and the birds have discovered that tasty treat. Even the Las Vegas desert tomato lady's Hawaiian Tropic (which were tasteless anyway) have quit.

AZRuss:

Have you tried misting them with the hose first thing in the morning? That often helps bring the temperature down. And are the plants suffering in general, or are just the blossoms doing badly? If they are getting too much sun, it helps to shade them, and keep them out of the midday sun with shadecloth or just planting them where they get morning sun.
Gardener's Delight is a wonderful cherry, I'm glad you're still getting those!

Carla in Sac

Thanks Carla. I will try misting them in the mornings. My set-up would be difficult to shade with shadecloth, unless I just toss it over the cages. Might be worth a try. To answer your questions, the blossoms dry up and about 25-30% of the leaves have turned brown. We have had single digit humidity and high afternoon winds all spring. Actually though, I'm more fatigued from fighting the birds than the desert climate this season. The birds love tomato seeds--they will actually hollow out a whole tomato and leave the skin!

sautesmom, your misting is washing the pollen off the stamen and some pollen is landing on the pistol so fruit set is happening. The fact that the pollen becomes gooey/sticky in temps above 90 for several days still applies and humidity is of little consequence. YOU are aiding MN and negating the natural responses of the plant. So you do the experiment and report back.

Hey sautesmom! I WANT to believe you, especially since I got my plants out late this year, but I have trouble with fruit set with high temps and low humidity, at least of some varieties. Not a problem for cherries, most hybrids. I'm pretty sure I've seen some data to support this in the UC Davis trials over the years. Would they be worth quoting? But I'm probably wrong.What mid and late season varieties do best for you? I'm a fan of shade cloth, which in low humidity DOES lower temps in my yard. Why mist if humidity is a problem?

Petzold:

Since I am a home gardener and I only live in one place, it's pretty much an impossibility for me to conduct an experiment contrasting growth in two different climates, on two different coasts.

Nanelle:

I didn't say ALL tomatoes grow well no matter how high the temps, but rather that it's not true that "it's impossible to get fruit set in tomatoes when temps hit 95 degrees" as is often repeated. I think it WILL be true at a certain temperature, maybe above 105, maybe 110? But our longest stretch here above 105 was 9 days, I think, and that's not long enough to test, really. My hunch is it's a sliding scale of heat and humidity, but I'm not a scientist! And just like your experience, some of my tomatoes are happy campers when we're having a heat wave, and some just croak. That's why I grow so many kinds, they all have different strengths.

Misting tomatoes in early morning brings down temperatures to reduce heat stress, but still allows the moisture to dry as the day heats up, so diseases don't set in.

I've put a link to everyone's previous discussions/suggestions for varieties below.

Carla in Sac

Here is a link that might be useful: Hot weather tomatoes

Hi sautesmom,

There have been studies done on heat effects related to pollen sterility, and it can make it sterile so that it is difficlut to acheive fertilization. Tomato Pollination

There are many variables to setting fruit, so different people may get different results. In my experience in areas where it is dry and hot, the 95º and above temperatures can stop pollination.

I'd give you more quotes, but I have to leave to take my husband to a doctor's appointment in a few minutes, but the link below gives some of the specific effects of heat on pollen and the fertility of tomatoes.

Bets

Here is a link that might be useful: The Effect of Heat Stress on Tomato Pollen

Aaaaaa! You people are making me crazy!!!! It's like you only see what you want to see, or read the parts that support what you already "know", and skim over the parts which conflict with your "knowledge".

OK, this is the LAST time I am going to repeat this--

Yes, I KNOW there are studies that say pollen dries out at 95 degrees, but my REAL LIFE experience growing tomatoes in Sacramento for 10 years, where daytime temps in July and August and September are almost always consistently ABOVE 95 degrees, is that I get tomatoes all summer long from many of my plants (but not ALL of them!) Which I have repeated ad naseum. Real life experience vs. studying pollen in a lab. Believe what you will, I'll be the one with tomatoes in August and September!

--off my soapbox--

Carla in Sac

Carla,

Do you have a lot of pollinators in your garden? I'm thinking maybe my tomatoes setting fruit in the heat may have to do with the abundance of bees I have that visit my garden. I've never seen them on the tomatoes but will bees help in pollination when it is hot out?

I actually seem to get getting more blossom drop now that it has cooled down and the bees aren't out.

Hi Carla! Me again.... Don't mean to be exasperating, but you know how forums can be. I checked the links, but since we are practically neighbors, and I believe our conditions (nights vs. days) to be somewhat unique, do you mind sharing the heirlooms that work best for you?

NVM; Found it

Large varieties for hot weather (above 100 degrees):
Mexico, Giant Belgium, Stump of the World, Marianna's Peace, Big Beef, Brandy Boy, Boondocks

Medium varieties: Stupice, Jetsetter, Arkansas Traveler, Burgundy Traveler, Manalucie, Moskvich, Orange Russian 117 (altough these can grow to beefsteak size), Peron, Jubilee, Heidi

and

just about all cherry/grape tomatoes.

Carla, I'm with you on your hypothesis. I live 120 miles south of you in the San Joaquin Valley. Usually, summer temps routinely run over 100 degrees. I've seldom noticed any reduction in the setting of fruit. On a side note, Merced County grows over 80% of the processing tomatoes in the country. There is a 80 acre field less than a mile from my house, blooming their heads off. If high temperatures were the only contributing factor to pollenization and fertilization, I don't think we'd be pumping out the tons and tons of tomatoes that we do in the middle of summer. I'm with you that the combo of heat and humidity affects the fertilization more than just heat on its own.

Just my own observation and not scientific opinion,

Elaine

Nanelle,

I missed your post asking for what does good here. So far, this is what I've had great success with:

NAR
Heidi
Opalka
Ace 55
Nebraska Wedding
Early Girl (too bad tastes like cardboard!)
Sungold

I'm trying some new types this year to see what works good:

San Marzano Redorta
San Marzano Nano
Rutgers
Persimmon

Elaine

Hi, our wild Florida Everglades tomatoes are climbing up the 6 foot fence in the back. Cherry tomatoes (certain varieties) do well in Florida summer heat and pouring rain.

We also have grape tomatoes bearing so heavy the stems fall over, but we don't stake any of the wild tomatoes, we just let them go crazy.
In October, we will plant the tomatoes that need cooler months to grow well.
In the meantime, every day we are picking and eating our wild tomatoes.
LMK if you have any questions about growing tomatoes in zone 10. Carolyn
johnmillerz2003 (at) yahoo.com

I made a mistake and planted Early Girl this year since I got a late start. I live in Alabama and it is very hot and humid all summer, and I didn't realize that Early Girl doesn't do well in this weather. I have healthy plants but I'm getting major blossom drop. I misted them this morning and I will move them (they are in pots) to a shadier area later on....is there anything else I can do? I'm so disappointed.

Literaleigh,

I have an Early Girl that I planted April 23rd in a TT and it has 4 tomatoes on it right now with more blooms....I think you will be fine. It is way hot here and we have blooms all over our plants. Check out the pics below.

Here is a link that might be useful: my container garden

Literaleigh,

I'm in Metro Atlanta area, which some people now classify as zone 8, so I think our growing conditions are very similar. I have several Early Girls, some planted in self watering containers and some in our raised garden. All are full of fruit and I haven't noticed any decline in blossoms or new fruit. Our temps are beginning to hit 90's now. Still below 80 at night though.

You said you got a late start so maybe your plants are just getting settled. Our Co-op department here gives Early Girls an excellent rating for handling the heat/humidity with good disease resistance.

Perhaps your tomatoes will do best with as much sun as they can get. As long as you keep the containers well watered.

Carla in Sac., it is hot and humid here in summer. I have similar experience as you with tomatoes. The plants slow down, but don't stop setting fruit until the cold weather sets in. Just my personal experience.

I'm on the western edge of Central Texas where we are hot and dry. I put my tomatoes on the west side of my house to protect from the wind (was awful last year and tomatoes did not produce). It is very hot on this side of the house until late in the day so put up tarps (requested shade cloth but DH bought tarps) which I believe helped to lower temps some.

We have been 106 degrees for several days (forecast has us over 100 for a week or more) and over 90 for weeks but while I was watering this morning I was finding new fruit that is setting. I picked my first ever Black Krim which some said does very well in the heat. I'm watching closely for the first color on Yellow 1884 Pinkheart. I have a HUGE (ONE only) tomato on Thessaloniki Oxheart; could feed a crowd LOL!

I have had a battle with spider mites...have had to take out some tomatoes in that row.

DH brought home shade cloth today so will see if there is a difference.

Good luck!

Peggy

I'm in Dallas and we are over 95/75 now. :\

I have a couple of plants under a shade cloth and it does seem to keep the temp 5-10 degrees cooler (have a thermometer in there). The plants are growing & budding like crazy, but remains to be seen if they will fruit or not. >_Important thing I noticed about the shade cloth- it does not seem to lower hot temps once established, but does seem to prevent them. So once the cloth is in place, don't move it for love nor money in the heat of the day! Today at noon it was about 95 in the sun but 84 under the cloth.

It's about 102+ in the sun right now, and about 96 under the cloth, which is still too hot but... oh well. :\ We'll see.

When I was in SC, I always had fruit all summer, and our temps were often over 90. In fact, there was always so much green fruit in the fall, we would start making green tomato pickles.

Here in FL, I never get fruit above 90, so it has to be the humidity.

Lemmings don't kill themselves? That's a good thing to know.

All this is nice BUT: !!!Just wondering , when the temps get consistantly over 90 and there is not much chance of fruit set , some plants 6/7 feet tall and unruly ,any damage done if I keep them cropped to 6/7 feet tall??? Does everything keep working properly lower on the plant where tomatoes are formed and ripening????

Hi cdgtxs,

Assuming you haven't been pinching off every "sucker" on your plants, go ahead and pinch off the growing tips at 6-7'. Your tomato plants will then put more growth in the other growing tips that are lower.

I'm doing the same on my tomatoes now as I don't want to have to climb ladders to pick tomatoes.

Brian

Thanks , I do not pinch any suckers , and plants are full except for lower 9 to 12 inches to keep leaves off ground.
thanks again.
CDGTXS

Hallandalegal, are the wild glades plants available anywhere a little north of you? I live in Boynton Beach and getting ready to plant a few more plants this week.

I'm very new to this forum. I thought the issue with tomatoes and squash setting fruit in hot weather was the night time temps. I live in central Florida where the temperature remains above 80 degrees at night from late spring to early fall. I had never heard the theory about heat and humidity before but it�s an interesting thought. I garden in a vertical hydroponic growing system so the roots are cooled by recirculation of water and nutrients. My tomatoes and squash did set fruit all summer but I expect much better results now that the weather has turned a little cooler.