Perennial morning glory (Ipomoea Acuminata ‘Blue Dawn’) is a tropical vine which can grow 25 feet in just one season. In zone 8, this plant dies back to the ground, but comes back strong in the spring. The flowers are electric blue in the morning and turn purple in the late afternoon. 'Blue Dawn' produces runners which can be very invasive, but are easily controlled with regular pruning. Planted in full sun on a trellis in a very dry part of my yard, 'Blue Dawn' made it through the summer with very little water. This vine's drought tolerance and reliability will continue to earn it a spot in my garden.