Potato vines include several species of climbing nightshades native to Central and South America. Varieties such as the Giant Potato Vine and the Chilean Potato Vine make attractive garden or greenhouse plants, flowering throughout spring and summer. They suit warmer southern states without prolonged cold winters. Gardeners will struggle to get a potato vine to flourish in USDA zones lower than zone 8, except if grown in a movable container.
Potato vines belong to the genus Solanum. Three main species are of interest to U.S. gardeners. The Chilean or Blue Potato Vine produces bright blue/purple flowers. The Giant Potato Vine grows well in conservatories, producing stunning purple flowers and pinnate foliage. Solanum jasminoides, known simply as potato vine by the Royal Horticultural Society, comes in two slightly different strains. The standard version blooms in light blue, while the Album variety has white flowers with a yellow centre.
All potato vines require full sun and grow best with a trellis or pole for support. The stems aren't vines in the true sense, but they do suit training and tying to trellis supports. Potato vines prefer fast-draining slightly alkaline soil of between pH 7.6 and 7.8. The plant doesn't need a large amount of watering and suits slightly dry soils. However, during the hot summer months, water weekly. The potato vine will die if temperatures drop lower than -6.67 degrees Celsius for too long, making it hardy from USDA zone 8 to 11.
S. jasminoides and the Giant Potato Vine grow to a height of 15 feet and spread to around 7 feet. The Chilean Potato Vine grows slightly smaller, to 12 feet tall and 5 feet wide. All varieties require support to reach maximum height or stems may break or become damaged. Potato vine plants require some pruning of damaged stems and any dying flowers. Take care not to break the curved spines on the Giant Potato Vine -- these help attach the plant to the trellis and are fragile.
The plant is tender and in cooler climates may drop flowers. However, they will grow in containers and can survive colder periods when brought into a conservatory or greenhouse until the weather warms up. In the right conditions, some potato vine varieties will become evergreen and produce flowers for long periods from spring to fall. Potato vines also produce bitter berries unsuitable for consumption. As relations to the nightshade, potato vines tend to be deer resistant.