PREFERRED SOIL pH: Adaptable
PREFERRED SOIL TYPE: Moist loam
PREFERRED LIGHT: Sun to partial shade
ATTRIBUTES: Trailing stems with large, lime, purple, or variegated pink, green, and white leaves; for pots, baskets, groundcover
SEASON OF INTEREST: Summer
FAVORITES: 'Blackie' for burgundy leaves; 'Margarita' for lime leaves; Tricolor' for leaves variegated in pink, white, and green
QUIRKS: Craves warm weather, warm soil
GOOD NEIGHBORS: Coleus. grasses, licorice plant, verbena
WHERE IT GROWS BEST: Sun or partial shade
POTENTIAL PROBLEMS: Grows poorly in dry soil
CRITTER RESISTANCE: Good except for slugs, deer
SOURCE: Bedding plants, cuttings, tubers
DIMENSIONS: Vines trail 18-36 in (45.7-91.4 cm) in length
Sweet Potato Vine in the Landscape
Ornamental sweet potato vine is the same species as the root vegetable that we put on the table, but these ornamental versions are valued for their large, fancy leaves that may be deep burgundy, bright chartreuse, or variegated with pink, white, and green.The first variety to capture the gardener's eye was 'Blackie', with its maple-leaf shaped, deep purple leaves. Perfect for sending plentiful stems spilling over the edge of containers or adding a splash of burgundy to beds, 'Blackie' was an overnight sensation. Invariably handsome and care-free, the plant has only one drawback: It lacks flowers. But who cares when it has such other attributes?
Then along came 'Margarita', a variety with abundant, silky, heart-shaped, chartreuse leaves on thick, wandering stems. 'Margarita' makes a fast-growing groundcover, carpeting the soil with its plush, golden leaves.
A third variety, named 'Tricolor', has smaller, heart-shaped leaves variegated with rose pink, white, and green. Its growth tends to be less robust than that of the other two, making it more appropriate for containers, where it can be easily tended.
Growing Sweet Potato Vine
Few annuals fill as many job descriptions as the sweet potato vine. While all varieties can handle full sun, the leaves of 'Blackie' blanch to a wine color when light levels are low. 'Margarita' grows equally well in sun or light shade, but in full sun the leaves attain striking red edges. As shade increases, the leaves of 'Margarita' glow with more of a golden hue, and often become larger, reaching 4-5 in (10.2-12.7 cm) in width. Sweet potato vines thrive in hot summer weather but wilt when rain is scarce. Weekly watering is usually sufficient in beds, but sweet potato vines in containers usually need water daily to prevent wilt. Avoid leaf spotting from sunburn by watering early or late in the day, when die sun doesn't shine directly on the leaves.
As care-free as sweet potato vines are, their juicy, big leaves do attract slugs, especially in damp, shady environments. If you see numerous clean-edged holes in the leaves, set out slug traps in the evening. Use either commercial traps or shallow saucers of beer. The yeasty smell attracts slugs, which crawl in and drown. Entire leaves that disappear overnight are usually the work of foraging deer. Tucking a bar of deodorant bath soap into plantings is a good -deterrent.
Increasing the Bounty
Cuttings 4 in (10.2 cm) long taken from stem tips of any sweet potato vine will root in a week in a glass of water. As soon as roots appear, plant the cuttings in a pot of loose, fertile potting soil, set it in a shady place, and water it daily. You can transplant the young plants to the garden or a container outdoors 2 weeks later, in warm weather. Sweet potato vines prefer warm soil and are quickly killed in frosty conditions.
Because sweet potato vines do produce tubers, you can dig those swollen roots in fall, before soil temperatures drop below 55°F (13°C), and store them over the winter in a paper bag in a cool, dark location. To start growth in spring, replant the tubers, laying them on their sides 2 in (5.1 cm) below the soil surface, after the soil warms in late spring.