Mexican oregano (Lippia graveolens), used in Tex-Mex and Central American cuisines, tastes like European oreganos but is not related to them. It is a member of the verbena family. Mexican oregano is a large shrub or small tree that is native to the southwestern US and Central America. It has small leaves and is covered with star-like white blossoms year round. Most gardeners keep it pruned to 4- to 5-feet tall but it can grow up to 8 feet in height.
Mexican oregano needs full sun and well-drained soil. Not surprisingly, it is drought tolerant. It is hardy in zones 10 and 11. In zone 9, it may or may not survive the winter depending on the temperature and amount of rain. Too much cold and wet will kill it. In northern zones, the plants are grown in containers and brought indoors in the winter or grown indoors year round.
Plants should be divided every two to three years to remain healthy. Division can be done in the early spring before the plants begin actively growing. Plant the divisions at least 12 inches apart. If growing Mexican oregano in a container, repot into a larger container, at least 2 inches wider, every two to three years or divide and replant the divisions into separate containers.
Propagation is most successful using cuttings of growing tips of the branches taken in the late summer. Once the cuttings have taken root, pinch back the plants to encourage branching.
Leaves can be harvested year round as needed for cooking. Rather than harvesting individual leaves, cut off branches as if pruning the plant. The leaves can be used to cook with while the stripped branches can be used as skewers or thrown into the barbecue to add flavor to your food.
Mexican oregano responds well to pruning and can even be pruned into topiaries or espaliers.