During April, and this year during May, I often get the question “Why are all the blossoms falling off my tomato plants?” There can be several reasons for blossom drop in tomatoes, lack of water, too much or too little nitrogen, insects or disease. But for us here on the coast, that’s not it. It’s the weather. When nighttime
temperatures drop below 55 degrees, tomato blossoms will drop off before fruit will set. For the past week our nighttime temperatures have been in the mid to upper 40’s and it looks like this will continue into next week as well. Tomatoes need nighttime temperatures above 55 degrees to set fruit. This is also why your neighbors may already have fruit on some of the plants they planted early (we often have a few warm weeks to kick of spring) and then you can’t seem to get anything to set. Don’t worry. Don’t overdue watering or feeding. Continue to give your tomato proper care and it will produce more flowers. Once it warms up at night, the fruit will set.
For more information, check out my post on How to Grow Tomatoes in Cool Coastal Climates