Ruta graveolens aka Rue

Ruta graveolens is known as common rue or herb of grace. It belongs to the rue family, Rutaceae. Its native range runs from the northern Balkans to Crimea. In the wild, it grows on rocks and dry hills. It also grows on old walls, often on limestone. Rue forms a rounded shrub with a woody base. Garden plants reach about 2–3.3 feet [0.6–1 metre] tall and wide.

Its soft leaves range from blue-green to blue-grey. They divide twice into small, rounded lobes, giving a fern-like look. Small glands dot the leaves, which smell strong when bruised. Leaves grow in an alternate pattern along smooth stems. New stems start green and turn woody with age. Rue keeps its leaves where winters stay warm. Sources differ on its lifespan, calling it long-lived or short-lived. NC State gives about five years, with seedlings replacing older plants.

Small yellow flowers rise in clusters above the leaves. Each flower has four or five petals. Bloom dates vary with place, spanning May through August. NC State also lists blooms into fall. Brown seed capsules follow the flowers and mature in fall. Each capsule splits into five parts and releases dark seeds. The flowers draw pollinators, and the foliage feeds several swallowtail caterpillars. These include black, anise, and giant swallowtails. Tiny parasitic wasps also use the plant and help control whiteflies.

Grow rue in full sun or some shade. It suits soil with moderate fertility and good drainage. It accepts acid, neutral, or alkaline soil, including sandy or loamy ground. It tolerates drought, dry rocks, and hot sites. Wet soil can lead to root rot. Sources list USDA zones 4–9, with NC State extending to 10. The RHS rates it H5 for UK gardens. Rue has few major pest or disease problems. Deer tend to leave it alone. Use it in borders, rock gardens, herb beds, or low edging.

Rue has a history of use in herbal medicine. Its leaves have also served as a bitter seasoning or tea. These uses do not make it safe to eat freely. Large doses can cause severe poisoning and may be fatal. Pregnant people should not use it, as it can cause miscarriage. Sap on skin can cause blisters after sun exposure. The RHS also warns of this risk in dogs. Wear gloves and long sleeves when handling rue. Other uses include insect repellents, red dye, and scented oils.