Moonflowers (Ipomoea alba) are relatives of morning glories and share their vining habit. The white or purple flowers are fragrant, and the vines can grow 12 to 18 feet in a year. Moonflowers perform well in poor soils and don't require applications of fertilizer. The plants thrive in dry conditions and generally are not bothered by pests or disease.
Time of Day
Those familiar with moonflowers know that they perform differently than most other flowers. The clue to their behavior is in their name. Moonflowers open in the evening and remain open at night. If you're looking for the blossoms during the day, you're likely to miss them. The flowers usually close by morning, but occasionally flowers will remain open well into the next day. Because they're open chiefly during the night, the plants rely on moths for pollination.
Time of Year
If you aren't seeing flowers yet, have patience. Moonflowers do not bloom until late in summer or early in the fall. You may have to wait several months after planting to see flowers appear. When the flower nears its bloom time, provide a light amount of supplemental water if rain is scarce, as the University of Arkansas Cooperative Extension warns that too dry conditions can cause failure to bloom.
Insufficient light levels are another reason moonflowers may fail to bloom. The flowers might open at night, but the plants need full to partial sun during the day to produce food. Moonflowers don't bloom well in the shade. If you find your flower in too shady a location, all is not lost. You can attempt to train the vine into a more sunny portion of the site. The plants perform well when transplanted from indoors, but morning glories do not like their roots to be disturbed. Established plants may not perform well if transplanted to a new location.
Moonflowers can be grown successfully in containers, which may allow you to bring them closer to outdoor sitting areas for greater enjoyment during their bloom time. You should allow container-grown moonflowers to become rootbound, as Texas A&M University's Aggie Horticulture department notes that crowded roots trigger an earlier bloom time.
You should nick the seed coat and soak the seeds before planting to help improve the rate of germination. For an ongoing supply of seed, leave the seed pods on the plant to dry naturally, then collect the pods, open them to remove the seeds and store the seeds in a dry area until the following spring.