I've seen one tom that was listed as setting fruit at 90f but can't remember what it was. All the rest are not going to set fruit above 85. You can try cooling the soil w/ a mulch, but likely won't get any fruit until you have cooler temps.

I have seen one product that was a clay coating applied as a spray. It said it kept temps 10-15 degrees cooler allowing for a longer growing season. I didn't book mark it since I do alot of foliar feeding w/ AVCT and it seemed to be counter productive to my needs. I don't expect toms all of Jul and part of Aug. I'll be happy if I get a few earlies before the heat sets in.

It's probably environmental factors. Sounds like yours is related to wildly-fluctuating temperatures.
Poor tomato fruit set takes place for many reasons. Prime among them are the occurence of extreme temperatures. When tomato plants experience extreme temperatures, either below 55° or above 90° F, for an extended period of time it may cause developing tomato blossoms to drop off. These blossoms drop off before the tomato fruits can set and therefore the tomato fruits do not develop. Another cause of poor fruit set in tomato plants is excessive nitrogen composition in the surrounding soil of the tomato garden. When the soil around tomato plants has a high nitrogen concentration, this promotes lush leaf growth to the detriment of tomato blossom and tomato fruit formation. Excessive nitrogen is the most common cause of lush foliage with no tomato fruits in the garden. Shading may also account for poor tomato fruit set. Be sure to locate your tomato garden where it will receive no less than six hours of sunlight per day. If the number of hours your tomato plants receive direct sunlight drops below six, it could be the cause of poor fruit set. The last, and often overlooked, cause of poor fruit set in tomato plants is very simply, dry soil. If your tomato plants are not receiving adequate water for their nourishment needs, tomato blossoms will dry and fall off plants.

Have you read through the FAQ here on Blossom Drop (that is what your condition is called ;) and the many reasons that can contribute to it? Linked it below. You might also want to Goggle 'blossom drop' fro even more info.

As already mentioned, air temps - actually it is the humidity more than the actual temp - is one factor. But inconsistent soil moisture levels, wind, and excess nitrogen fertilizer are others and while TomatoTone isn't especially high in N, you say you use it "regularly"? Maybe cut back on it because big lush well growing plants with no fruit is often a sign of over-fertilization.

Dave

Here is a link that might be useful: Blossom Drop FAQ

thanks for the info - great link digdirt

so much to learn about tomatoes

I plant in mid-March to try to obtain fruit before our high temps hit but I am also running out right now with an electric toothbrush to pollinate the few plants that have blossoms:))

The temps have moderated throughout this whole week, ranging from 60 in the a.m to 88 in the p.m. When temps subside like that, will plants automatically want to set fruit, or does it need to stay "cool" for an extended length of time? Given the fact that my plants are growing vigorously with many blooms, should I just keep doing what I'm doing or what? Thanks again for the help.

I am having similar problems. My plants are beautiful, with some tomatoes, but not a lot of blooms. We planted mid March, and had terrible wind for the next 6 weeks, then very high temp and this last week, it has moderated again. I had been feeding every week, but I think I am going to cut back to every other week. I have a drip system, is it OK to leave it on?

JGR

The temperature effects on pollination are nearly immediate if you have fresh blossoms, low humidity, and enough plant movement to encourage the pollen movement (usually the wind or a gentle human shaking of the plants) -- pollination of a single blossom doesn't require extended optimal temperatures for more than 1-3 days. You'll see when a tiny tomato appears at the base of the blossom. Blossoms that continue opening during those optimal conditions will continue to pollinate.

IOW, if you have fresh blossoms during the weather you describe as well as plant movement and low humidity, they should pollinate and set fruit while those conditions exist. Once the tomato blossoms have pollinated and you have tiny tomatoes, those will continue to develop, though if the temps extend beyond the optimal ranges or it's extremely humid or it's utterly becalmed, you aren't likely to get new tomatoes forming because they can't pollinate.

Here is a link that might be useful: Tomato Pollination

Thanks anney, much appreciated. I have numerous blossoms already on the plants, so hopefully this week some pollination will occur.

I had been feeding every week

Alarm bells going off. ;)

Ronnie - as explained in detail in the FAQ linked above, over feeding, especially N, is one of the main causes of blossom drop.

So when someone says My plants are beautiful, with some tomatoes, but not a lot of blooms. I have been feeding every weekit jumps off the page like a fire alarm.

Tomatoes seldom require weekly feedings under any circumstances - even in containers and even then only a diluted feeding. Excess fertilization gets you huge lush plants with minimal production of fruit.

Your plan to cut back on the fertilizer - WAY back - is a very wise one if you want any fruit. ;)

And, per the FAQ excess soil moisture and inconsistent soil moisture levels is yet another cause of blossom drop. So, when you say I have a drip system, is it OK to leave it on? I assume you mean it is on some sort of an auto timer - plants get watered whether they need it or not??? You might want to re-evaluate that approach.

Dave