When you look at a sweet potato (Ipomoea batatas), what you see will be a enlarged underground root which has little indentations where new growth may begin. Should you maintain a sweet potato about for a long time, shoots will begin to emerge from these areas, and if you plant the sweet potato, then you’ll find a sweet potato vine. If you are lucky, you may get to see it blossom. The flowers look like small morning glories. Sweet potatoes do not usually flower often out the tropics.
Edible Sweet Potato
Christopher Columbus introduced sweet potatoes to Europeans on his fourth voyage from the West Indies. Early Spanish explorers took sweet potato to the Philippines and Portuguese explorers disperse it farther into Asia and Malaysia. They are in the morning glory family, Convolvulaceae, together with funnel-shaped flowers coloured white to lavender, depending on the cultivar. There are plenty of varieties which differ from the colour and moistness of the flesh. Flesh colors are white, orange, purple and red. Flesh consistency is either dry-fleshed or moist-fleshed. Sweet potatoes are an important crop in Asia, Africa, Malaysia, and South and Central America, and they rank as the sixth most important food crop in the world.
Sweet potato flowers are made of five fused petals. They have a deep, tubular throat topped by a sloping apartment rim known as the blossom’s limb. The limb is usually white, and the throat is pale to deep lavender. In some varieties, the blossom is entirely lavender. The five male flower parts, the pollen-bearing stamens, are fused to the inside of the blossom’s throat. The female flower part, the pistil, rises from the bottom of the blossom and is situated in the throat. The base of the blossom contains abundant nectar from yellow glands, a reward for pollinating bees. Cupping the blossom’s bottom on the exterior are the green sepals. The blossoms are 1 to 2 1/2 inches long and 1 to 2 inches broad.
You want to get up early to see sweet potato flowers at their very best. They start right after daybreak, and have usually disappeared by noon. They only stay open for a single morning. The chief pollinators are honeybees and bumblebees. Flowers occur in clusters of one to 22, sprouting from where leaves join the stem. Sweet potatoes blossom best when days are short during winter. Where freezing temperatures occur, this means putting the plant in a greenhouse or indoors for the winter. The breeds of creamy sweet potatoes most commonly grown in america do not produce flowers frequently. You can encourage flowering by putting the sweet potato in a container to limit root growth and by not fertilizing the plant using a high-nitrogen formula, which promotes vegetative growth at the expense of flowering.
Sweet potatoes are a tropical plant, growing in U.S. Department of Agriculture plant hardiness zones 9 through 11, with winter protection needed in USDA zone 9. It is a summer annual crop in USDA zones 8 and lower. Because flowering is uncommon, seeds for sweet potatoes aren’t accessible except for breeding purposes. The plants are grown from slips instead, which can be rooted stem-bearing pieces of sweet potato roots. Vegetative propagation ensures you get the cultivar you desire. Most sweet potatoes produce large, vining plants which require a large growing region. Several cultivars, known as bush varieties, have shorter vines for smaller gardens or containers. Sweet potatoes require a few months of warm weather for the best production of roots. Roots require a curing period following harvest.
Ornamental Sweet Potatoes
You can get varieties of sweet potatoes selected for attractive foliage instead of edible roots. Ornamental sweet potatoes have vibrant 3-inch leaves, mainly heart-shaped but a few deeply lobed. The eaves can be yellow-green, light green, red or deep purple to nearly black. They make great ground covers cascading plants for containers or for spilling over partitions. The vines produce big, white-fleshed roots which are edible, but not too delicious. If the plants produce flowers, then they are tucked among the leaves and pale pink. Ornamental sweet potatoes also grow in USDA zones 9 through 11, but are grown as annuals in cooler climates. Several cultivars are “Sweet Caroline” with a wide array of leaf colors, “Illusion Garnet Lace” with greatly cut burgundy leaves, and “Illusion Midnight” with nearly black leaves.