Morning glories are twining vines that can completely cover a wall or arbor in flowers in a single summer. Large-leaved varieties provide quick shade, if given a trellis or screen to climb on. Morning glories open their flowers with the rising sun and close them in the afternoon. Native to the tropics, morning glories are easy to grow, but need a long season of heat before they begin to flower heavily. Several conditions can inhibit flowering.
Morning glories are members of the genus Ipomea. They have heart-shaped leaves and 4- to 6-inch-wide tubular flowers that last a single day. They are vines that climb up to 20 feet. They open their flowers in the morning to attract specific pollinators for seed production. Perennial in their native tropics, morning glories are annuals in temperate zones, either grown from seed or started indoors in pots. They take a long time to bloom from seed; some varieties won't start blooming until late summer. Morning glory seeds are poisonous if ingested. Ipomea nil, I. purpurea, I. lobata and I. tricolor are the most common varieties for home gardens.
Morning glories are slow starters in temperate climates. A cool, wet spring can set them back so they produce no flowers until mid-summer. Gardeners can get around this by sowing seeds indoors 6 to 8 weeks before the last frost is due, or when the soil has warmed to 65 degrees Fahrenheit. Morning glories do not transplant well, so seeding them in individual peat pots allows them to be planted without disturbing their delicate roots. Too little or too much water will retard flower production. Morning glories do not like drought and need regular moisture, but dislike wet roots. Gardeners must learn what amount their plants need to produce bountiful blooms.
Give morning glories full sun in a well-drained bed. A hot spot in your garden is perfect for these tropical heat-lovers. They need a trellis or fence to climb on to be free to produce flowers. Water regularly and do not let them dry out, or flowering will falter. Don't water during rainy periods; soggy soil damages their roots and decreases flower production. Soils that are too rich reduce flowering because the energy goes into producing leaves. Do not add fertilizer, compost or manure to nitrogen-rich soil.
Morning glories are well suited as container plants. Provide sturdy supports to climb on or set them in baskets on top of a wall or arbor and let the vines hang down. Maintain moist but not soggy soil for best flowering. Check the containers daily, particularly during hot weather, to make sure the water-loving morning glory's roots haven't dried out. If that happens, check the top of the vine. If foliage is healthy and new growth is vigorous, the plants will come back, but flowering will be drastically decreased for a period.