My cucumbers have lots of flowers but they're not getting any fruit.
Cucumbers With Lots of Flowers but No Fruit
Sounds like a pollination problem. Cucumbers have male and female flowers, but only male blooms appear on young plants. As they grow, the female flowers will appear, and bees will carry the pollen from male blooms to female blooms. Bee activity can be low when it's cool or when pesticides have discouraged them from the area.
If there appears to be little pollinator activity, you can pollinate by touching a male bloom with a cotton swab or small paint brush, then touching a female bloom (with miniature fruit below its petals). If not fertilized, the fruit will not enlarge, and the flower will drop from the plant in a few days. The blossoms of both sexes are open and fertile only during the morning hours of one day.