If you are concerned about losing flowers from your squash and zucchini, read on.
The male flowers bloom first and fall off the plant. Then a week or so later both male and female flowers will bloom. Male flowers are on long skinny stems called peduncles and at the base of the female flower is a swollen ovary or fruit. It is important to have insect activity during the bloom time. The blossoms stay open for about 4 hours and if they do not get pollinated in the time frame that they are open they will not produce a fruit, or it will be misshapen due to lack of pollination.
These plants can be hand pollinated with a small paint brush if there is a lack of pollinators.
Other conditions can cause a plant to not produce fruit. If it’s too hot only male flowers will be produced and female flowers will be delayed. Drought stress can cause female flowers to abort. Heat, drought and too much water can cause the flowers to wilt and die. In these instances, the pollinators are not able to transfer pollen from plant to plant.
High nitrogen levels can also delay female flower production causing fruits not to mature in time. Cucurbits can be pollinated by any insect pollinator, but they are most often pollinated by bumblebees and squash bees which forage in the morning while the flowers are open.
Source: Carrie Jagger, OSU Extension-Morrow County