Rue, or Ruta graveolens, is a perennial shrub historically valued as a medicinal and culinary herb, though its use has become primarily ornamental today. This aromatic plant belongs to the Rutaceae family, the same family that includes citrus fruits. Commonly known as Herb-of-Grace, rue has a long history of cultivation and symbolism. Understanding its native environment and growth habits is key to successfully incorporating this unique plant into a garden.
Native Origin and Global Spread
Rue is naturally found in the Mediterranean basin, including Southern Europe, North Africa, and the Balkan Peninsula. Its native environment is characterized by dry, rocky, and uncultivated land, establishing the plant’s preference for hot, dry sites and well-drained soils. Cultivation has spread Ruta graveolens throughout temperate regions worldwide, where it thrives across USDA hardiness zones 4 through 9. Its adaptability to dry soil makes it a popular choice for xeriscaping. In some areas, the plant has escaped cultivation and become naturalized along roadsides.
Identifying the Rue Plant
Ruta graveolens is a woody-based subshrub that generally grows in a rounded, bushy form, reaching an average height and spread of 2 to 3 feet. The most distinctive feature is its foliage, which is a unique glaucous, or bluish-green, color with a finely divided, fern-like appearance. When the leaves are bruised, they release a strong, pungent aroma.
The plant produces small, dull yellow flowers in clusters, called corymbs, typically blooming from mid-summer into late summer. These flowers are unusual because the first flower in the cluster often has five petals, while the others have four. New stems are soft green but become woody with age.
Caution must be observed when handling the plant, as its sap contains psoralens which can cause phytophotodermatitis. Contact with the foliage followed by exposure to sunlight can lead to burn-like lesions and blistering. Wear gloves and long sleeves when pruning or working closely with rue to prevent this phototoxic reaction.
Optimal Growing Conditions
Rue thrives best in full sun, requiring at least six hours of direct sunlight daily for dense growth and healthy flowering. It can tolerate partial shade, particularly in extremely hot climates where afternoon protection may be beneficial. Once established, the plant is highly drought-tolerant.
The most important soil requirement is excellent drainage, as rue is susceptible to root rot in wet conditions. It prefers poor, dry, or rocky soil and performs well in low-fertility environments. Avoid rich, moisture-retentive soils, opting instead for a well-drained mix with a pH range between 6.0 and 8.0.