I am sorry for this delayed reply to your gardening question. The spring rush has brought a deluge of questions and we are working hard to catch up!
Tomatoes don't set well when the temperatures are too hot or too cold. You have not been having either weather extreme lately so I suspect it is either due to them not being moved by wind (the shaking causes the pollen to fall around in the flower and pollinate itself. Another possibility is very high nitrogen causing vine growth at the expense of fruit set.
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!
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