Why Are My Tomato Blooms Breaking Off at the Elbow?

Environment

• The environment around your tomato plants can cause your tomato blooms to break off without producing fruit. Air temperatures above 85 degrees Fahrenheit during the day or 70 F at night over a period of several days can cause tomato blooms to drop. Excessively high or low levels of humidity can prevent your tomato blooms from self-fertilizing and cause them to break off and drop. The ideal humidity range is 40 to 70 percent. If the humidity around your plants is too low, you can mist the plants with water to promote fertilization.

Pollination

• Tomato blooms are fertilized when pollen is transferred from the male reproductive organs of the flower to the female organs. Tomato plants are normally pollinated when wind or an insect knocks pollen loose inside each bloom. Indoor tomato plants often suffer from breaking blooms because they are protected from insects and the wind. These blooms can remain unfertilized, causing their blooms to fall off without producing fruit. If you are growing indoor tomatoes, you can gently shake the stems bearing newly opened blooms to fertilize them. This simulates the force of the wind and helps promote pollination.

Care

• Excessive amounts of nitrogen in the soil promote the growth of stems and leaves at the expense of blooms and fruit. Avoid applying fertilizer with a concentration of nitrogen above 5 percent while your tomatoes are blooming; higher levels can cause your plants to drop their blooms and start growing stems and leaves. Tomato plants also need regular watering when their blooming period coincides with warm weather. Your tomatoes should be watered deeply and evenly, as well as often enough to prevent the soil from drying out.

Fruiting

• Heavy crops of fruit strain the resources of a tomato plant. In many cases, tomato plants do not have access to enough nutrients to support all of the fruit and blooms that they produce. If your tomato plant is already producing a bountiful harvest of tomatoes, it is normal for some blooms to breaks off without bearing fruit. In most cases, this problem will go away once you begin harvesting some of the fruit from the vine.