Horticulture/Rosmarinus officinalis

Rosemary (Rosmarinus officinalis) is a woody, perennial herb with fragrant evergreen needle-like leaves. It is native to the Mediterranean region and in Uruguay. It is a member of the mint family Lamiaceae, which also includes many other herbs. The name derives from the Latin name rosmarinus, meaning "dew of the sea".

Description
Forms range from upright to trailing; the upright forms can reach 1.5 m tall, rarely 2 m. The leaves are evergreen, 2-4 cm long and 2-5 mm broad, green above, and white below with dense short woolly hairs. The flowers are variable in color, being white, pink, purple, or blue.

Growing conditions
Well-drained soils in full sun. Grows well in containers.

Varieties

 * 'Albus': white flowers
 * 'Arp': leaves light green, lemon-scented
 * 'Aureus': leaves speckled yellow
 * 'Benenden Blue': leaves narrow, dark green
 * 'Blue Boy': dwarf, small leaves
 * 'Golden Rain': leaves green, with yellow streaks
 * 'Irene': lax, trailing
 * 'Lockwood de Forest': procumbent selection from 'Tuscan Blue'
 * 'Ken Taylor': shrubby
 * 'Majorica Pink': pink flowers
 * 'Miss Jessop's Upright': tall, erect
 * 'Pinkie': pink flowers
 * 'Prostratus'
 * 'Pyramidalis' (a.k.a 'Erectus'): pale blue flowers
 * 'Roseus': pink flowers
 * 'Severn Sea': spreading, with arching branches; flowers deep violet
 * 'Tuscan Blue': upright

Uses
The fresh and dried leaves are used frequently in traditional Mediterranean cuisine as an herb; they have a bitter, astringent taste, which complements oily foods, such as lamb and oily fish. A tisane can also be made from them. They are extensively used in cooking, and when burned gives off a distinct mustard smell, which can be used to flavor foods while barbecueing.

Since it is attractive and tolerates some degree of drought, it is also used in landscaping, especially in areas having a Mediterranean climate. It can in fact die in over-watered soil, but is otherwise quite easy to grow for beginner gardeners. It is very pest-resistant.

Rosemary is easily pruned into shapes and has been used for topiary. When grown in pots, it is best kept trimmed to stop it getting too straggly and unsightly, though when grown in a garden, rosemary can grow quite large and still be attractive. It can be propagated from an existing plant by clipping a shoot 10-15 cm long, stripping a few leaves from the bottom, and planting it directly into soil.

Rosemary is a useful food preservative, according to research published in 1987 by Rutgers University, New Jersey. Researchers at Rutgers patented a chemical derived from rosemary that compares favorably with BHA and BHT in its preservative properties.

Rosemary can be added as an unusual extra flavoring in lemonade.

Medicinal uses
Rosemary has been found to be a stimulant and mild analgesic, and has been used to treat headaches, poor circulation, and many ailments for which stimulants are prescribed.

It can be used as a disinfectant, as a mouth wash and to treat fever or rheumatism.

Externally it can be used in hair lotions; a few drops of Rosemary oil massaged into the scalp, then rinsed with an infusion of nettles can revitalize the hair. Used in this manner, it is supposed to prevent premature baldness. Rosemary is also reported to stop dandruff.

Hungary water was first invented for a Queen of Hungary to 'renovate vitality of paralysed limbs'. It was used externally and prepared by mixing 180g of fresh rosemary tops in full flower into a liter of fresh rosemary tops in full flower into a liter of spirits of wine. Leave to stand for four days then distill. It is also supposed to work as a remedy against gout if rubbed vigorously on hands and feet.

Rosemary has a very old reputation for improving memory, and has been used as a symbol for remembrance (during weddings, war commemorations and funerals) in Europe, probably as a result of this reputation. Students in ancient Greece are reported to have worn sprigs of rosemary in their hair while studying for exams to improve their memory, and mourners would throw it into graves as a symbol of remembrance for the dead. In Shakespeare's Hamlet, Ophelia says, "There's rosemary, that's for remembrance".

Rosemary and its constituents carnosol and ursolic acid have been shown to inhibit the growth of skin tumors and to provide a natural anti-oxidant protection against skin cancer and photodamage.

Health Precautions: In some cases, rosemary can cause autoimmune diseases. Rosemary in culinary or therapeutic doses is generally safe, however precaution is necessary for those displaying allergic reaction, or those prone to epileptic seizure. Rosemary essential oil is a powerful convulsant; if applied to the skin, it may cause seizures in otherwise healthy adults or children. Rosemary essential oil is potentially toxic if ingested. Large quantities of rosemary leaves can cause adverse reactions, such as coma, spasm, vomiting, and pulmonary edema (fluid in the lungs) that can be fatal. Avoid consuming large quantities of rosemary if pregnant or breastfeeding.

Maintenance
Cut flowers off to encourage more leaf production. In hardiness zones below 7, the plant should be brought indoors in winter.

Propagation
Most commonly propagated via stem cuttings.

Harvesting
Cut leafy stems (removing flowers, if present). Dry by hanging upside down in a dark area.