It's been humid here in the Northeast.... The pollen in your flowers may be getting "stuck" and not able to pollinate properly. Have you tried gently shaking each of the plants to help the pollen out? I do this every day and it does help.

And on the subject of the tomatoes setting little fruit, I am having the same problem, it's the weather we had in June.

Its probably the weather. I am also in zone 7a, and had an unusually soggy spring too. Things are finally looking better lately. I agree with jerseygardengirl about the pollen ~my tomatoes are in containers, and I gently tap the edge of the container every day to dislodge any pollen. I am lucky to have lots of bumble bees and honey bees around too. Summer's not over yet ~it should get better from here on out! :-)

I dont know what your daytime/nighttime temps and humidity have been like where you are. First, if the nighttime temps are too cool, below say 55*, or too warm, say over 65* or the daytime temps are too warm, say over 95* or too cool, say below 70*, tomatoes may not set fruit. Also, high humidity can make the pollen sticky and clumpy which can inhibit pollination. Or if it is too dry the pollen dries up and blows away making it difficult for the flower to get enough pollen to set fruit. The flowers do not have an unlimited shelf life. If a truss of flower does not pollinate within a certain time the plant simply cuts it loose and starts again with new flowers that hopefully will find temps/humidity more conducive. That is my dilema when it comes time to plant, Here it can be very cool at night up into mid June. That means I can have nice size plants with few flowers, or the flowers I do get do not set fruit. It is frustrating because all that energy and expectaion seems to get the better of us. Like a kid who says that it take forever for Christmas to come.

One additional comment. You can try watering your plants with 2 tablespoons of epsom salt in a gallon of water every couplee of weeks. Epsom salt helps the tomato plant set fruit by providing magnesium. Magnesium is one of the critical nutrients for proper flower development and setting fruit. You can even foliar feed with epsom salt at a rate of 1T per gallon of water when flowers begin to appear in an effort to give them a greater boost.

I know it is too late now but next season when you plant put a cup of epsom salt, not just right under the transplant but spread it in a wide circle - where you expect the tomato plant's roots to go during the growing season. This can be 18-20 inches away from the stem. This is good because as the plant's roots grow they will have access to the magnesium when the flowers begin to develop.

There are several reasons why tomato plants do not set fruit, but the most common are: too much nitgrgen (this causes lots of green growth with little flowers), temps/humidity not being right, or insufficient nutirients. Magnesium and sulphur are often deficient in the soil and epsom salt is a good source of those things. We get focused on the N-P-K and forget about all the other ingredients that are necessary for healthy plant growth.

People talk a lot about soil PH. No matter what kind of ph your soil currnetly is, compost has a neutralizing effect. So compost is the best way to make any soil more neutral.

Analyze the environmental factors along with adding some epsom salt and see what happens. Keep a journal so you can documant any progress, or lack of it.

Hope this helps,

Tom