Don't be alarmed chaz. Blossom drop occurs. High humidity I believe. They should keep setting..I will shake the plant gently or flick them every so often while they form.
The pollen clumps on the inside of the anther cones under certain conditions,then it's not loose enough to get to the stamen......

Most likely because they are over-crowded. Unless it is a huge container, something like 50+ gallons. What varieties are the plants? Indeterminates or determinates? How often do you water? What and how much have you fed them? What has the ambient air temps been lately - day and night?

The condition is called 'blossom drop' and I linked the FAQ on it below. Search will pull up lots of discussions about it too.

Dave

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

First off,thank you for the fallow ups. The container i am using is about 30 gallon tub,the type 4 kegs. it gets 80-100 degrees often,i water every day 1/2-3/4 gallons of watter and use a veggie fertilizer about every 4 weeks. about 1/2 of the flowers have fallen off. i have 12 tomatoes on the 3 plants now that are down low on the stalk but the upper ones are falling off. i don't know if this is normal? thank you

It will help to know your approximate location. You can add this to your page or your (zone(optional)) on all your postings. A 30 gallon container is big enough for 3 plants if properly spaced and deep enough with proper drainage. What did you use for soil? 80-100 degrees "often" means what? 80 at night and 100 day? 80-100 covers most of the mid to lower and east/western US in the summer months. Lack of pollination is most likely the problem and this could be due to high temps and/or humidity. Some shading around noon to 3pm might help if plants are in full sun.

Tomatoes drop blossoms when temps are extreme - say, if you have 90+ degrees for several days in a row. Other stress factors can be under-watering and over-fertilizing. It's hard for flowers to get pollinated when they're under stress. Sounds like you're doing great with the watering schedule. I'd probably fertilize a little more in containers -- every 10-14 days. Gentle shakes to the plant help pollination, too, as was suggested!

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