Do you have a lot of bees and pollinators always buzzing around the spot you put the plants out? If not they might not be getting found and pollinated in time.

Is it still too cold to leave them outside? You should have gads of time left for more flowers to fruit anyways right?

Tomatoes are self pollinating and do not need insects for pollination. They are fussy about temperatures, however, and will not set fruit if they are too high or too low. While temperatures are the most common reason tomatoes fal to set fruit there is also moisture, again too much or too little and soil nutrient levels.

I beg to differ - tomatoes are self-fertile, but all plants need some assistance with pollination, whether it be wind, birds, insects or just jostling by passing critters. Tomato pollen is held in the interior of the flower and needs movement to carry it to the stigma and achieve fertilization. Bees are the natural pollinators of tomatoes and in fact they are often introduced into greenhouse growing situations to accomplish this process. A number of manual operations can achieve the same effect.

Most effective fruit set is provided by a rather narrow temperature window - no colder than 50F and no warmer than 70F and improper or incomplete fertilization can result in aborted or malformed fruit.

Here is a link that might be useful: tomato pollination

oosul,
Try flicking the stems lightly so the flowers vibrate.
I wasn't getting any fruit to set either, until I started shaking the plants daily. Now I am finally seeing small fruit, but not much.
What types of heirlooms are you growing?

According to my books and my personal experience the upper range for tomatoes to set fruit is 85. If the range was 50-70 we Fl. gardners would be in big trouble!!! There are varieties that push these limits such as Heatwave VFFA Hybrid that is reported to yield best at 90-96. Solar Set VFF Hybrid is reported to set fruit even up to 92 during the day and 72 at night. Unless I'm dealing with an unusual variety I look for fruit set at 55 - 85. However, I do have a few tomatoes growing now that have mature fruit on them and we have had a freeze and many cold days. Go figure....Wonder how long the ideal temps must last for the fruit to set and not drop?

Peggy--that's interesting that you don't usually get fruit set at temperatures above 85. I've seen tomatoes set fruit in West Texas when temperatures were above 90 (and these weren't heat set varieties). I believe this has something to do with humidity and night time temps. West Texas has cool nights and low humidity, which apparently allows tomatoes to set fruit even when daytime highs are above 90. No fruit set seems to occur the high temperature is above 95, however, except for cherries which do well an any condition.

I've never paid much attention to night-time lows being to cold--but have heard the cutoff to be around 50 degrees.

Lack of wind to shake the blossoms could also be a problem, especially in urban areas. Excessive fertilizer could also be at fault.

Jason

Peggy, I agree it CAN'T be restricted to 50-70 deg, since my garden is ALWAYS well above 70 (except at night), and I currently have fruit setting on my Yellow Brandywine, Carbon, Cherokee Purple, and Druzba (but still waiting on Marianna's Peace).

I am growing brandywine, yellow perfection,
and cherokee purple. The flowers on these heirlooms are strange. I took a q-tip to try and get some pollen on it and then hand pollinate the other flowers or even the same one, and not even a speck of pollen was on the q-tip after I repeatedly swabbed around the entire flower. Is this normal for heirlooms?

I'm growing heirloom toms.inside under a 400w cmh light. To polliate, an oscillating fan set on low is quite sufficent...I'm in an un-heated space so I simply set a thermistatically controlled heater @ 67F. When light's on, the temps range between 72-79. I've had no problem setting fruit. Remember to that vegies will set fruit when they're ready. Having some blossum drop is normal...

Here is a link that might be useful: {{gwi:134681}}

oosul,
Try the link below to the tomato forum. I've learned lots there from very helpful experts.

Here is a link that might be useful: Tomato forum