You’ve set the stage – planted healthy vegetable plants, then watered, weeded and waited. And now your vegetables are blooming, but not producing fruit.
Situations where vegetable plants are flowering, but not setting fruit may indicate a problem with flower pollination, according to Kansas State University horticulturist Ward Upham.
“There may be several reasons for pollination problems, which usually vary by species,” Upham said. “One condition that can affect several species at the same time is over fertilization. Too much nitrogen causes the plant to emphasize vegetative growth, often to the detriment of fruit production.”
Over fertilization can lead to a delay in flower production and a decrease in fruit set among the flowers produced, Upham said.
Squash, cucumbers, watermelon, and muskmelon can have a couple of other problems, he added. The early flowers on these plants are usually all male. The production of both male and female flowers becomes more balanced as time passes.
You can easily tell the difference between the two because only the female flower has a tiny fruit behind the blossom, he said. If you have both, have not over-fertilized, and still have a problem, make sure you have pollinators. Look for the presence of bees visiting the plants. If you don’t see any, try hand-pollinating several flowers by using a painter’s brush to transfer pollen from the anther of the male flower to the stigma of the female flower.
“If you get fruit on only those flowers you pollinated, you need more pollinators. Make sure you aren’t killing them with overuse or misuse of insecticides,” Upham said.
Tomatoes are wind pollinated and therefore not dependent on pollinators. But they have another possible problem, which is temperature. Tomatoes normally won’t set if the night temperature is below 50 degrees Fahrenheit due to sparse pollen production. They also won’t set when nighttime temperatures are above 75 degrees F and daytime temperatures are above 95 degrees F with dry, hot winds.