Wait until early morning, if possible. Pollination is best done in the morning when flowers are wide open and conditions are ideal.
Identify a male cucumber flower. The male flower will have a thin, plain stem at the base of the flower. A female flower will have a swollen stem in the shape of a cucumber. This is where the cucumber will eventually grow.
Cut the male flower at the base of the stem. Take care not to cut any of the connecting vine.
Remove the flower petals by peeling them back or cutting them off of the stem. This will reveal the anther in the center of the flower. The anther is where the pollen is located.
Touch the anther to the stigma in each female flower. The stigma is the center of the female flower.