Sweet Potato (Ipomoea batatas)

Edible Sweetpotato, Ornamental Sweetpotato, Sweet Potato

Growing sweet potato vines is something every gardener should consider. Grown and cared for like average houseplants, these attractive vines add a little something extra to the home or patio. Keep reading for more ornamental sweet potato info.

I. Appearance and Characteristics 

The sweet potato (Ipomoea batatas) is a dicotyledonous plant that belongs to the bindweed or morning glory family, Convolvulaceae. Its large, starchy, sweet-tasting tuberous roots are used as a root vegetable. The young shoots and leaves are sometimes eaten as greens. Cultivars of the sweet potato have been bred to bear tubers with flesh and skin of various colors. Sweet potato is only distantly related to the common potato (Solanum tuberosum), both being in the order Solanales. Although darker sweet potatoes are often referred to as “yams” in parts of North America, the species is not a true yam, which are monocots in the order Dioscoreales.

The sweet potato is native to the tropical regions of the Americas. Of the approximately 50 genera and more than 1,000 species of Convolvulaceae, I. batatas is the only crop plant of major importance—some others are used locally (e.g., I. aquatica “kangkong”), but many are poisonous. The genus Ipomoea that contains the sweet potato also includes several garden flowers called morning glories, though that term is not usually extended to I. batatas. Some cultivars of I. batatas are grown as ornamental plants under the name tuberous morning glory, and used in a horticultural context.

The plant is a herbaceous perennial vine, bearing alternate triangle-shaped or palmately lobed leaves and medium-sized sympetalous flowers. The stems are usually crawling on the ground and form adventitious roots at the nodes. The leaves are screwed along the stems. The leaf stalk is 13 to 51 centimetres (5 to 20 inches) long. The leaf blades are very variable, 5 to 13 cm (2 to 5 in) long, the shape is heart-, kidney- to egg-shaped, rounded or triangular and spear-shaped, the edge can be entire, toothed or often three to seven times lobed, cut or divided. Most of the leaf surfaces are bare, rarely hairy, and the tip is rounded to pointed. The leaves are mostly green in color, but due to the accumulation of anthocyanins, especially along the leaf veins, they can be purple in color. Depending on the variety, the total length of a stem can be between 0.5 and 4 metres (1+1⁄2 and 13 feet). Some cultivars also form shoots up to 16 m (52 ft) in length. However, these do not form underground storage organs.

The hermaphrodite, five-fold and short-stalked flowers are single or few in stalked, zymous inflorescences that arise from the leaf axils and stand upright. It produces flowers when the day is short. The small sepals are elongated and tapering to a point and spiky and (rarely only 7) 10 to 15 millimetres (3⁄8 to 5⁄8 in) long, usually finely haired or ciliate. The inner three are a little longer. The 4 to 7 cm (1+1⁄2 to 2+3⁄4 in) long, overgrown and funnel-shaped, folded crown, with a shorter hem, can be lavender to purple-lavender in color, the throat is usually darker in color, but white crowns can also appear. The enclosed stamens are of unequal length with glandular filaments. The two-chamber ovary is upper constant with a relatively short stylus. Seeds are only produced from cross-pollination.

The flowers open before sunrise and stay open for a few hours. They close again in the morning and begin to wither. The edible tuberous root is long and tapered, with a smooth skin whose color ranges between yellow, orange, red, brown, purple, and beige. Its flesh ranges from beige through white, red, pink, violet, yellow, orange, and purple. Sweet potato cultivars with white or pale yellow flesh are less sweet and moist than those with red, pink or orange flesh.

II. How to Grow and Care

Sunlight

Sweet potato vines can take little shade. Full sun is preferable. It’s prudent to give your plants less shade cover at the height of summer since, in scorching climates, they can get sunburned in temperatures of 110 degrees or more. The sweet potato plant thrives in moist, well-draining soil. These vines can develop root rot, which can destroy them if the ground is too wet for an extended period. You may want to apply an acid-forming fertilizer to your soil if the pH is above 8.0 and your soil is quite alkaline. If your soil is healthy and balanced, fertilization is not necessary. Occasionally using it can promote rapid development. It’s preferable to water moderately. The soil should be damp but not drenched.

Temperature and Humidity

Wait until the last frost passes before planting in the spring or early summer. Sweet potato vines require nighttime temperatures above 40°F to prevent damage. Extended periods of lower temperatures, around 55°F, can slow growth. Like other tropical plants, sweet potato vines thrive in warm, humid climates but don’t require high humidity levels to survive. During prolonged periods of heat, water more frequently so the plant does not dry.

Watering

Sweet potato vines should receive at least an inch of water weekly through rainfall or watering. Keep the soil moist but well-draining even though these plants are relatively drought-tolerant once established. Proper water care helps sweet potato vines to produce vibrant foliage and prevents wilting. During the summer or extended periods of heat, water more frequently.

Soil

Well-draining soil is essential for sweet potato vines as it is prone to root rot. These plants will tolerate most soil pHs, but slightly acidic to neutral is preferred. Choose an all-purpose potting soil with nutrients or organic matter if growing in containers. Amend the soil outside with compost.

Fertilizing

Use a well-balanced and slow-release fertilizer during planting and throughout the growing season. To increase the foliage vibrancy, add a water-soluble monthly fertilizer, such as a 5-10-10. This fertilizer will increase sweet potato vines’ natural growth and vigorous nature.

Pruning

Prune sweet potato vines as necessary throughout the spring, summer, or fall. Remove dead, damaged, or diseased vines with sterilized pruning shears. Use pruning as a way to curtail vines from spreading beyond its boundaries. When grown in direct sunlight and with proper care, sweet potato vines need trimming to avoid overcrowding and potentially overtaking other species. Alternatively, pruning is one way to encourage more vines to emerge. Use garden shears to cut about one-fourth of an inch above the leaf node to stimulate new growth.

Propagation

Sweet potato vines are easy to grow from existing plants. Cutting is the best way to propagate, but you can also plant the plant’s tubers in the spring.

To propagate with cuttings:

  • If you live in a place that gets wintery weather, you’ll want to take a cutting from your outdoor sweet potato vines in the autumn before the first frost. The plant dies off when exposed to frost. You’ll need pruning shears or snips, a jar of water, and a sunny spot.
  • Using clean, sharp garden pruning shears, cut off a branch that has several leaf nodes. Remove the leaves off of the bottom few inches.
  • Submerge the stem in water. In a few days, the plant will grow roots. 
  • The plant can live indoors in water in a sunny spot throughout the winter. Keep the water level constant. Empty the water and refill the jar with clean water every week to discourage bacterial growth.
  • Come springtime after the last frost, you can replant it in the garden in moist, well-draining soil in a sunny spot outdoors. Harden off the plant before placing it in the garden to acclimate it to outdoor conditions.

To propagate using its tubers:

  • Sweet potato vines produce tuberous roots. You can save the tubers for the next season. You’ll need a box, peat, or vermiculite, and a cool, dry place, such as a basement, crawlspace, or root cellar.
  • Dig up the tubers before the first frost, and let them dry. Bury them in peat or vermiculite. Do not let them touch.
  • In spring, the tubers will sprout. Inspect the tuber for signs of disease or infection. You’ll need a clean, sharp, non-serrated knife. Cut off and discard any blackish areas, visible wounds, puckered spots, or discoloration.
  • Divide the tuber using the sterile knife, making sure each tuber has at least one eye and some shoots or roots.
  • Plant them after the last frost in moist, well-draining soil, 2 inches deep at least 2 feet apart in a sunny spot.

Grow from Seed

Sweet potato vines are rarely grown from seeds, since they can grow from cuttings and their tuberous roots. Also, since it doesn’t flower reliably, you can’t always get seeds. Many varieties are sterile. If you’d still like to try to grow the plant from seeds, take these steps:

  • Presoak seeds for 12 hours in warm water to help with germination.
  • Fill a seed-starting tray with a light, soil-less starting mix. Sprinkle the seeds over the tray, spacing them 3 inches apart. Cover them with a light dusting of starting mix.
  • Spray the mix with water from a spray bottle and cover the tray with plastic wrap or a humidity dome.
  • Store the tray in a warm place. Keep the starting mix evenly moist
  • Once you see seedlings, remove the plastic wrap and move it to a sunny window or under a grow light.
  • Sweet potato vines dislike root disturbance, so transplant immediately after sprouting or grow in biodegradable pots.
  • Harden off seedlings before transplanting them in the ground or outdoor container.

Pests and Diseases

Common Pests & Plant Diseases

The most common problem with sweet potato vines is discovering leaves riddled with holes. Holes are the handiwork of the sneaky golden tortoise beetle. To control this pest, plant a different selection or spray your plants according to label directions with neem oil or spinosad. Depending on your location, other potential pest infestations include aphids, caterpillars, whiteflies, and weevils. 

Fungi like verticillium wilt or fusarium can infect the soil surrounding sweet potato vines. These fungal infections, starting with yellowing leaves at the base, spread and cause crown rot. 

Common Problems 

Sweet potato vines are prone to pests and fungal infections, but proper care and early detection can help eliminate and treat many of its issues. Here are a few problems that impact sweet potato vines:

Curling Leaves 

Underwatering causes sweet potato vines’ leaves to curl. Keep the foliage vibrant by watering deeply every time, making the soil consistently moist but not waterlogged. Also, if the leaves appear filled with holes, a tortoise beetle or other pest might be present. Use soapy water or neem oil to restore the leaves.

Leaves Turning Black/Brown

Sweet potato vines’ foliage will turn black if experiencing frostbite or fungal infection. If the weather isn’t the cause, root rot likely caused the black leaves. Starting with yellowing or browning leaves, sweet potato vines will start by wilting, usually from overwatering. Treat fungi by always using proper water drainage and spraying with fungicides. Maintain good airflow between the vines and plenty of sun exposure.

Potting and Repotting 

Choose a taller pot or basket (hanging or otherwise) of any material so the vines have ample room to spill and trail over the edge of the container. These plants look lovely in window boxes, as well. Make sure that the container you choose has ample holes for drainage. Fill the pot with good-quality potting soil mixed with compost. Water the container once a week until the water begins leaking from the drainage holes. Plants will thrive if the container is kept in full sun rather than shade.

Overwintering

Depending on your climate, cold-hardy sweet potato vine tubers can go dormant in frost-free areas, sprouting new vines to replace the dead vines in the spring. If your area experiences temperatures below 40°F, moving sweet potato vine cuttings indoors or storing tubers helps to start plants the following spring. Leave cuttings in water until the spring, or transplant them into a container to grow throughout the winter.

III. Uses and Benefits 

  • Nutrition

Cooked sweet potato (baked in skin) is 76% water, 21% carbohydrates, 2% protein, and contains negligible fat (table). In a 100 gram reference amount, baked sweet potato provides 90 calories, and rich contents (20% or more of the Daily Value, DV) of vitamin A (120% DV), vitamin C (24% DV), manganese (24% DV), and vitamin B6 (20% DV). It is a moderate source (10-19% DV) of some B vitamins and potassium.

Sweet potato cultivars with dark orange flesh have more beta-carotene (converted to a higher vitamin A content once digested) than those with light-colored flesh, and their increased cultivation is being encouraged in Africa where vitamin A deficiency is a serious health problem. Sweet potato leaves are edible and can be prepared like spinach or turnip greens.

  • Culinary 

The starchy tuberous roots of the sweet potato are by far the most important product of the plant. In some tropical areas, the tubers are a staple food crop. The tuber is often cooked before consumption as this increases its nutrition and digestibility, although the American colonists in the Southeast ate raw sweet potatoes as a staple food.

The vines’ tips and young leaves are edible as a green vegetable with a characteristic flavor. Older growths may be used as animal fodder.

Molecular gastronomy

Freezing a sweet potato until solid, baking at a low temperature, then increasing to a high temperature brings out the sweetness by caramelizing converted sugars.

  • Dyes

In South America, the juice of red sweet potatoes is combined with lime juice to make a dye for cloth. By varying the proportions of the juices, every shade from pink to black can be obtained. Purple sweet potato color is also used as a natural food coloring.

  • Aquariums

Cuttings of sweet potato vine, either edible or ornamental cultivars, will rapidly form roots in water and will grow in it, indefinitely, in good lighting with a steady supply of nutrients. For this reason, sweet potato vine is ideal for use in home aquariums, trailing out of the water with its roots submerged, as its rapid growth is fueled by toxic ammonia and nitrates, a waste product of aquatic life, which it removes from the water. This improves the living conditions for fish, which also find refuge in the extensive root systems.

  • Ornamentals

Ornamental sweet potatoes are popular landscape, container, and bedding plants. Grown as an annual in zones up to USDA hardiness Zone 9, they grow rapidly and spread quickly. Cultivars are available in many colors, such as green, yellow, and purple. Some ornamental varieties, like ‘Blackie’, flower more than others. These ornamental cultivars are not poisonous, and although the leaves are edible, the tubers do not have a good taste.

Sweet Potato (Ipomoea batatas) Details

Common name Edible Sweetpotato, Ornamental Sweetpotato, Sweet Potato
Botanical name Ipomoea batatas
Plant type Annual
Hardiness zone 9a, 9b, 10a, 10b, 11a, 11b
Growth rate Fast
Height 6 ft. 0 in. - 10 ft. 0 in.
Width 6 ft. 0 in. - 10 ft. 0 in.
Sunlight Full sun (6 or more hours of direct sunlight a day)
Soil condition High Organic Matter
Flower color Pink
Leaf color Gray/Silver