Zucchini Flowers

• Female flowers remain attached to the fruits until naturally falling off.Tom Brakefield/Stockbyte/Getty Images
  
  Male flowers are the first to appear on zucchini plants, opening before female flowers. The anatomy of male and female flowers differs. The pollen-producing parts of the male flower are the anthers and filaments located on the stamen. These are often fused together. Male flowers often open, release the pollen and then fall off. Female flowers must remain on the plant until the zucchini starts to grow, and this can only happen when pollination is successful. Without pollination, female flowers fall off and plants won't produce any fruit.
  
  

Poor Pollination

• Insects take pollen from a male flower and place it on the stigma of a female flower.Jupiterimages/Photos.com/Getty Images
  
  The pollen on the flowers that will ultimately produce zucchini fruits is sticky and isn't spread by wind. It is necessary for a pollinating insect, such as a bee, to take pollen from the male flower and transfer it onto the stamen of the female flower. In cases where plants produce all male or all female flowers, pollination cannot occur. The use of chemical insecticides such as carbaryl, which is highly toxic to bees, can also contribute to poor pollination or a lack of pollinators.
  
  

Temperature Problems

• Temperature problems can cause flowers to wilt and fall off.Jupiterimages/Comstock/Getty Images
  
  Zucchini plants grow best when soil temperatures are above 60 degrees Fahrenheit. If seeds or plants are planted too early, or the temperature suddenly drops, that can contribute to a loss of flowers. Extreme heat is another potential reason for the loss of flowers. Although zucchini is a summer squash, if the temperatures are excessively hot during the day and don't get sufficiently cool at night, plants would be unable to set fruits and this could cause either male or female flowers to fall off the plants.
  
  

Hand Pollination

• Zucchini plants have male and female flowers on the same plant.Hemera Technologies/Photos.com/Getty Images
  
  Even if there are enough male and female flowers, the absence of pollinating insects can make it difficult for pollination to occur. Pollen must successfully unite with egg cells on female flowers. Without that connection, female flowers will also fall off. Hand pollination, though labor intensive, will transfer pollen from the stamen of the male flower to the stigma of the female flower. Remove pollen from the male flower with a small artist's paintbrush and gently brush it on the stigma of the female flower. Another method is to break a freshly opened male flower off the plant. Gently remove the petals so that the pollen-bearing part of the male flower is visible. Roll pollen from the freshly opened male flower onto the stigma of the female flower.