Let me introduce you to a hardy native herb with bright fall color and good flavor. Texas tarragon (Tagetes lucida) is a tough perennial hardy to Zone 7. Its sturdy branches usually reach 2-3 feet although I've seen it as tall a four feet. The long, thin leaves are dark green with a slight serrated edge. Texas tarragon will be happy growing in well-drained soil but will also tolerate a wide range of soils and conditions. It prefers at least four hours of direct sun but will also bloom in shady areas.
Texas tarragon is also known as Mexican mint marigold. It originated in Central America and gradually migrated north to the U.S. Southwest. Instead Texas tarragon provides a slightly sweeter substitute for French tarragon. This is fortunate for Texas gardeners because French tarragon grows poorly in our hot, humid climate.
Late fall is when Texas tarragon really shines in the garden. Just before Thanksgiving this herb puts on a cheerful show of golden marigold-like flowers. In my area, these blooms are a signal that winter is just around the corner.
Texas tarragon is a low-maintenance plant with few pests or problems. Besides the occasional visit from the spittle bug or the four-line beetle in late spring not much attacks it. During the growing season keep an eye out for young plants springing up in difficult-to-reach spots. In late fall after the blooms begin to fade, prune stems down to the ground.