The Morning Glory and Moon flower are both members of the family Ipomoea and are close relatives of the sweet potato. Morning glories are great vines to plant wherever you need some quick, temporary color on a fence, lamppost, mailbox, or the post that holds the clothesline.
The morning glory can also grow on the vegetable garden fence, but need to keep an eye on them lest they twine around vegetables and thwart their growth. They can be supported by a very light trellis, and are also good vines to grow in containers. The common morning glory (Ipomoea prupurea) is a hardy annual.
Modern cultivars are derived from this and from other species which are tender perennials, including I. tricolor and I. nil. Most are bright blue, but some are pink, red white, or one color striped or edged with another. All are twining vines with soft stems and heart-shaped leaves. The Morning Glory’s name comes from the fact that it closes up its trumpet-shaped flowers against the afternoon sun, though it stays open on cloudy days. Morning glories are twiners they reach out, pirouetting in their predetermined, typically clockwise direction, seeking something to grab hold of.
Moonflowers, also called moon vines, are closely related and look like large white morning glories. Some botanists call them ‘Ipomoea alba’ or ‘I. bona-nox’, others ‘Calonyction aculeatum’. They are vigorous tender perennials that can be rather rampant in warm climates but are prized for their fragrant, night-blooming flowers. Which are lovely in moon gardens, the garden planted to be admired at night from midsummer to fall? Grow them as an annual north of Zone 8.
Because of their similar cultural needs, these two flowers are regularly grown together. When paired, the night-blooming moonflower and the day-blooming Morning Glory combine to put on quite a show. Due to their fast-growing habit, these tender, short-lived perennials create a living screen in no time. Moreover, if you want to grow these plants, then both morning glories and moon flowers need full sun and moist, well-drained soil.
But too much water, as well as too much nitrogen-rich fertilizer, can lead to rampant stem and leaf growth but few flowers. Hence, plant them 8 to 12 inches apart, and ½ inch deep in a moistened furrow. In short-season climates give moon flowers humusy soil, and mulch and give them regular feedings with a balanced liquid fertilizer all of which will speed up growth.
In long-season areas give it strong support. The seeds of both vines germinate slowly; it helps to nick them with a file or soak them overnight before planting. I saw morning glories directly in the garden. But moon vines need a very long season to bloom and should be started indoors in peat pots about four weeks before you expect to plant them. Also neither transplants easily unless peat pots are used.