Tarragon is an herbaceous perennial that grows and overwinters in USDA Zones 4a to 8b. Russian tarragon is sometimes called estragon, which, as one of our female family members pointed out, is her spirit animal for a few days each month. A. dracunculus is a hardy plant with a milder flavor and aroma than French tarragon. Care It prefers a warm, dry climate. In more humid zones, give your plants plenty of breathing room. Tarragon requires well-drained, even sandy soil. Too rich a soil will cause your plants to become "leggy" and less dense. Amend the soil with aged compost upon planting, but don't go overboard fertilizing established plants. Full sun will produce the best plants. It tolerates light afternoon shade, but you'll likely lose out on flavor and plant vigor. Growth Habit Tarragon is an upright-growing plant that can reach heights of five feet tall and about 30" wide within a year, though generally it's more compact and, on average, grows to about two feet high. Sometimes, tarragon grows wider than tall, especially when the ends of the stems are regularly pinched to promote a shrubbier plant. Russian tarragon's spreading root system can cause the plant to crowd its neighbors; divide its roots every year or so to create new plants, or to keep them within your preferred growing area. Toxicity Tarragon oils are considered toxic to dogs, cats and horses. Ingesting the herb may result in mild digestive upset.