Purple Horsemint, Lemon-Mint. Native to the Midwest and Southern US. This easy to grow herb reaches up to 4 feet tall and produces whorls of purple blooms all summer. Very attractive to butterflies, bees and beneficial insects and the aerial parts make a delicious lemon flavored tea. Makes an excellent back border or screen when planted densely. Prefers full sun and well drained soil. Hardy annual self sows readily. Hardy to Zone 9.