Rue (Ruta graveolens) was once a common herb. It has fallen out of favor since many of the medicinal qualities it was believed to have were found to be inaccurate and even dangerous. However, rue deserves to be grown for its foliage and flowers in a contemporary garden. The foliage is a bright blueish-green and fern like. The flowers are sprays of small yellow blossoms with green centers. Rue is native to the Mediterranean and Southern Europe.
Rue has a strong smell that repels pests such as dogs, cats, and Japanese beetles. It works well as a companion plant to more vulnerable plants, such as vegetable plants. Rue is a semi-woody, perennial, herbaceous plant, so can be pruned into hedges or topiaries. It is attractive to butterflies and deer do not like it, always a plus. Finally, rue makes a very attractive cut flower when in bloom.
Care should be taken when handling rue. Its sap is caustic and contains a substance called rutin. Not only will it irritate the skin but can cause chemical burns. It also makes the area where the sap touched sensitive to the sun, so you are more likely to get sun burned there than is usual.
Rue grows to about two and a half feet high. It is hardy in zones four to nine. It prefers hot, dry, rocky soil in the full sun, although it will grow in more fertile soil. Once established, it rarely needs attention or watering.
Rue is propagated by seed. The small seeds need light to germinate. They should be strewn on the surface of a tray of potting soil. Press the seeds into the soil gently so there is good contact between the seed and soil. Place in a warm, well lit area. In one to four weeks, the rue seeds will sprout. If you prefer to sow the seeds outside, they can be sown once the temperature reaches 68 degrees F and all danger of frost is past.
Rue should be mulched in the winter to protect it from the low temperatures. As a perennial, rue will come back every year if protected from the elements in the winter.
Do not plant rue near basil, sage, or mint. The rue will retard the growth of these plants.
To keep rue blooming, deadhead the flowers once they begin to fade. If you want to allow rue to self-seed, leave the fading blooms on the plant. They will turn into pods of seeds. Once the pods are dry, harvest them and place them in a paper sack until the pods pop open and the seeds fall out. These seeds can then be used next year to seed more rue plants.
It is illegal to use rue in food in the United States, but in Europe it is used as a flavoring agent in salads, sausages, cheeses and a few other foods. The herb is very bitter so is used in very small quantities in these foods.