keri, does it get cool at night in your location?

I live near the coast and our nights are always cool. Some large fruited tomatoes will not set at my location, I have never managed to get Delicious to set as an example. My Early Girl plants will be covered with fruit while my Delicious and Porterhouse will be bare. I get good sized fruit from Supersteak at my more inland community garden, but no fruit set here at the coast.

If your heirloom is large fruited and listed as a long maturity type, this could be your problem.

Flowers will fall off if nighttime temps are too low and the pollenation/fertilization process is not completed quickly.

Here is some garden voodoo you can try. To assist pollenation, buzz the flowers during the warm part of the day by holding the backside of a electric toothbrush against the stem of the flower. You should be able to see a small stream of pollen fall from the flower, ensuring complete pollenization.

Or you can just shake the plants a couple of times a day. But toothebrushes and shaking won't work if conditions are not right for pollenization, meaning, the pollen has to be viable.

Please go to the FAQ link at the top of this first page and read about Blossom Drop. Temperatures, both high and low determine when self pollenization can and can't occur and sustained high humidity can clump the pollen and also make it non effective.Details are in that FAQ article.

Carolyn

wow, so the flowers are breaking off b/c they are not polinated?
Its not cold over night here. It never gets below 60* in the summer.
I had two flowers turn to a very small fruit tho, and it broke off too.
It happens at the stem of the flowers and small fruit, just below the base of the flower.

keri, it doesn't get below 60F here as far as I can tell, but still some tomatoes just won't set.

At my community garden that is more inland, Gogosha still won't set. It is listed as 85 days (late) maturity and large over 1 lb.

The tomatoes that have not set for me have been:
Mortgage Lifter - 2.5 lb
Delicious - 1 to 2 lb
Gogosha - 1+ lb
Hughs - 1 to 2 lb
Porterhouse - 2 to 4 lb

All the smaller fruited varities I have tried have set and I have tried quite a few.

One tomato's cozy warm night may be a bit chilly for another variety, I surmise.

So, do you know what variety heirloom you are growing, or what size fruit you are expecting?

There are other contributing factors to blossom drop besides temps - tho that is the most common one. Excess nitrogen fertilizer is another and it is easier to control. Winds, high humidity, etc. all contribute as well.

Dave

Here is a link that might be useful: Blossom Drop

Hello coolbythecoast, i am not sure the variety of heirloom but they were supposed to be medium sized fruit.

Given all of these excellent well informed answers, my guess would be polinization. (or lack there of!)

I dont see any new flowers on the plant or any hope of them at this point. I will keep an eye on things and try the brush/shake/vibrate techniques suggested.

Thanks so much for all of your help!
-Keri