How to Grow and Care for Morning Glories
Morning glories belong to several different genera in the family Convolvulaceae, but the most numerous and familiar one is Ipomoea. Some are shrubs, but the majority are vines. They have funnel-shaped flowers that come in many colors. You are probably familiar with conventional morning glories, such as Ipomoea purpurea and Ipomoea nil, but there are hundreds of morning glory species. They are close relatives of the sweet potato, and are also related to bindweed. Morning glories are not as invasive as bindweed - they do reseed vigorously but can be kept in check by cutting off the spent flower heads. Most species are annual but some are perennial. In most morning glories, the flower is only open during the morning, after which it starts to fade, hence the name.
Plant morning glories in spring, after all danger of frost. If you live in a cold climate, you might want to start the seeds indoors a few weeks before bringing them outside. Most annual varieties (and some perennial types as well) are sensitive to frost and should be sown as early as possible after the danger of frost is over.
Most morning glories, especially the annual varieties, are propagated by seed. Abrade the seed gently, then soak in water for 24 hours. After that, plant in soil. The seedlings usually come up within a week, but some may be stubborn and may take a few weeks to sprout.
Some tuber-forming and perennial varieties may take a few years to flower from seed, but the annual varieties usually bloom within a few months of germination.
When it is time to plant, transplant the morning glories into a spot that receives full sun. Do not plant near other plants as most morning glories are very vigorous climbers. You may want to use a trellis for support. Make sure that the morning glory receives good irrigation. Morning glories do not require much fertilizer, and in fact, too much fertilizer (especially nitrogen-rich fertilizer) may cause excess leaf growth and few to no flowers at all.
In order to stop them from becoming weeds, morning glories should be deadheaded. This means that their spent flowers should be removed to prevent excess seed production. If you wish to save a few seeds for next year, leave only a couple of seed pods on the vine; however, morning glories often hybridize with each other, creating new varieties if two related varieties are in close proximity, so they do not always come true to seed and you often don't know what you are going to get!
Always check the legality of morning glories in your area before growing them. Some species of morning glory, such as Ipomoea aquatica and Ipomoea hederacea, are classified as noxious weeds in several states. Also, in Arizona, most Ipomoea species are technically illegal to possess, although nobody has been arrested yet for this.