Zucchini is often the big joke of the garden. This big producer is the butt of many garden pranks from neighbors leaving them on porches and running off, to finding the really BIG one tucked in the back of the plant. Sometimes, however, gardeners report no fruit at all on their squash plants. What could be the cause?
The most likely cause is lack of pollination. Squash, melons, and cucumbers belong to a family, called “cucurbits” and have a flowering habit which is unique among vegetable crops. Each plant produces two kinds of flowers, male and female, both on the same plant. In order for fruit set to occur, pollen from the male flower must be transferred to the female flower. The pollen is sticky; therefore, wind-blown pollination does not occur. Honeybees are the principal means by which pollen is transferred from the male to the female flower. If you don’t have bees in your garden, you don’t have cucurbits. When bees are absent, fruit set on cucurbits is very poor and often nonexistent. If only a few bees are present in the area, partial pollination may occur, resulting in misshapen fruit and low yield.
In big farm production, farmers rent hives of bees to be placed in their fields to pollinate the crops. Unless you as a home gardener who is lucky enough to either have your own bees or a neighbor with a hive, your will have to depend on native bees. It is very important to plant bee loving plants in or near your vegetable garden. The bees will be drawn to those plants and will also pollinate the squash. Careful use of pesticides is also important. Pesticides, (even the organic variety) are non selective and will kill bees as well as insect pests.
When no bees are in the garden the dedicated gardener can substitute for the bee by pollinating by hand. Here is a good article about how to identify male and female flowers and now to hand pollinate. http://bonnieplants.com/2012/07/pollination-problems-give-hand-pollination-a-try/