Cucumber flowers are small and yellow with five wrinkled petals per blossom. They are found on the vines of the cucumber plant. The flowers grow under large green leaves that help to provide shade and protection from the environment. Most plants produce male and female flowers, although some genetically modified cucumber plants only produce female blossoms.
The cucumber plant produces male flowers before the female flowers grow. A plant that grows both male and female flowers is called monoecious. Immature cucumber vines create smaller flowers than the older plants. The cucumbers grown from the flowers that appear first on a new vine are often incorrectly shaped and contain fewer seeds.
Female cucumber flowers grow individually on a long thick stem. Below the petals on each flower is a bulbous ovary. The cucumber fruit is found in miniature on the stem behind the immature female flower. After the flower is pollinated by insects or bees, the cucumber fruit begins to grow. Inadequately pollinated plants will produce cucumbers that are green and misshapen.
Male flowers are a very bright yellow and grow close to the stalk of the vine. The stem of the male flower is much thinner and shorter than the female flower stem. Visible within the flower are three stamens. Many male flowers grow in clusters on the cucumber vine.
The male cucumber flower begins to open nearly ten days earlier than the female flower bud. For each female flower that blooms on the cucumber plant, there will be ten to twenty male flowers present. A few indoor varieties of cucumbers require the removal of the male flowers to prevent the fertilization of the female flower. If fertilization occurs, the mature cucumber fruit will taste very bitter.
When gardening, a person must be careful not to disturb or damage the delicate yellow cucumber flowers. Once damage occurs, the cucumber vine may be trellised to protect it until another growing season. If the cucumber flowers are falling off the vine before producing any fruit, there may be a pollination problem. Hand pollinating the female blooms with grains of pollen from the male flowers may help to avoid any further loss of the female flowers.
For large crops of cucumbers, bees may be imported to pollinate the flowers. The standard number of bees necessary for the proper pollination of the cucumber flowers is one bee for every 100 flowers. Some farmers choose to delay pollination until the vines have matured longer; this allows time for larger female flowers to grow, resulting in better tasting cucumber fruit after harvest.