Lemon verbena is an herbaceous perennial that is also grown as an annual in cooler climates. The plant is native to South America and is the strongest of the lemon herbs. Lemon verbena can reach up to 6 feet in height, and produces small spikes of flowers in summer. These flowers, however, are often overlooked in favor of the highly valued leaves. Lemon verbena's leaves smell strongly of lemon and are used to flavor teas, desserts, salads and sweet beverages, such as lemonade. The plant is winter hardy in zones 8 through 10. Grow it indoors during the winter in all other zones.
Plant lemon verbena in the spring in loose, well-drained, alkaline soil. Choose a ting location that receives full sun or full sun with partial afternoon shade in hot climates. Grow lemon verbena in containers if temperatures drop below freezing in your area and bring it indoors during the winter. Use a well-drained potting mix for indoor or container-grown plants.
Water lemon verbena once every two weeks, allowing the soil to dry out in between watering. The plant is tolerant of dry conditions and should never be over-watered or root rot could occur. Do not provide supplemental watering on weeks that receive more than 1 inch of natural rainfall to prevent over watering.
Feed lemon verbena plants once every six weeks using an all-purpose garden fertilizer. Follow the instructions provided by the manufacturer for the correct application rate. Water the the soil before and after fertilizing to thoroughly distribute the nutrients and prevent the plant's roots from being injured by the high concentration of nitrogen.
Prune lemon verbena plants as necessary to control straggly growth. Use clean pruning shears to snip off any leaves or branches that begin to grow out of bounds. Overgrowth is less of a problem when the leaves are regularly harvested. Lemon verbena is easily trained as a topiary or into a formal shape if you have the skills.
Harvest lemon verbena leaves anytime during the growing season, although they will have the strongest scent and flavor if harvested just before the plant blooms. Hold large leaves at the base where they meet the stem with one hand, and then gently strip each side of the leaf from the vein with your other hand. Pinch off smaller leaves with your fingers.