Ipomoea batatas 'Blackie', also known as Sweet Potato Vine, this annual features stunning purple, almost black cascading foliage. Ipomoeas are great additions to combination planters, but they can sometimes overwhelm less vigorous plants. Ipomoeas also make great annual groundcovers in the landscape. They love the heat and humidity (growing up to 36" a week in the Deep South), cooler temperatures and low humidity cause them to stay more compact.