Annual vinca, occasionally called periwinkle, is not related to the perennial ground cover with the same common name. In fact, annual vinca is native to Madagascar and is prized for its nonstop flower show from early summer till fall. Annual vinca is drought tolerant and requires almost no maintenance to keep it looking terrific. Use it en masse in beds and borders or tuck it into mixed containers with other annual flowers. Annual vinca grows 12 to 18 inches tall and comes in pink, purple, red, white, magenta, and bi-colors. The flowers are also attractive to butterflies. Hardy in zone 10.