Rosmarinus officinalis, also known as “Dew of the Sea,” boasts a profusion of deep blue flowers resembling a sprawling ocean, a shrub species from the Labiatae family of dicotyledonous plants. It is also a natural aromatic plant.
Rosemary, with its high ornamental appeal, also possesses significant industrial value. Extracts from its flowers and leaves yield antioxidants with excellent antioxidative properties, as well as rosemary essential oil. These antioxidants are broadly used in pharmaceuticals, fried foods, oily foods, and the preservation of various fats and oils.
Rosemary essential oil, on the other hand, finds application in fragrances, air fresheners, ant repellents, and daily-use chemicals for sterilization and insecticides.
Basic Introduction
Native to the Mediterranean coasts of Europe and Africa, rosemary has been introduced and cultivated in our country’s gardens. Its leaves carry a tea fragrance with a spicy, slightly bitter taste.
A small amount of dried or fresh leaves are used as food seasonings, particularly for lamb, duck, chicken, sausages, seafood, stuffing, stews, soups, potatoes, tomatoes, radishes, other vegetables, and beverages.
Due to their strong flavor, they are typically removed before eating. Historically, rosemary was believed to enhance memory, symbolizing remembrance and loyalty in literary works and folk tales. Mildly stimulating, it is a common aromatic ingredient in tonics and ointments in traditional medicine. Currently, its essential oil is an ingredient in many cosmetics.
Distribution Range of Rosemary
Rosemary is indigenous to the Mediterranean coasts of Europe and North Africa. It is primarily cultivated as an economic crop in southern Europe. China began to introduce it during the Cao Wei Dynasty and now predominantly cultivates it in most regions of southern China and in Shandong.
What Does Rosemary Look Like?
Rosemary is a shrub that can reach up to 2 meters in height. Its stems and old branches are cylindrical, with a dark grey bark that splits longitudinally and peels off in chunks. The young branches are quadrangular and densely covered with white, star-shaped down.
The leaves are often crowded on the branches, with very short stems or no stems, linear leaf blades measuring 1-2.5 cm in length and 1-2 mm in width.
The leaf tips are blunt, the base gradually narrows, and the edges are entire and curl towards the back. They are leathery, slightly glossy on top, nearly hairless, and densely covered with white, star-shaped down on the underside.
The flowers are almost stalkless, opposite, and a few are clustered at the tips of short branches to form terminal inflorescences. The bracts are small and stemmed.
The calyx is ovate-bell-shaped, about 4 mm long, densely covered with white star-shaped down and glands on the outside, hairless on the inside, with 11 veins.
It has a two-lipped form, the upper lip nearly round, entire or with very short 3-teeth, and the lower lip with 2-teeth, the teeth being ovate-triangular.
The corolla is blue-purple, less than 1 cm long, covered with sparse short soft hair on the outside, hairless on the inside, the tube slightly protruding, the limb two-lipped, the upper lip straight, 2 shallowly cleft, lobes ovate, lower lip large, 3 cleft, the middle lobe the largest, concave, tilting downwards, margin toothed, the base constricted into a handle, lateral lobes oblong.
Two stamens develop, attached below the lower lip of the corolla, the filament with a small tooth pointing downwards in the middle, anthers parallel, only one chamber fertile.
The style is slender, far exceeding the stamens, the tip unequally 2 shallowly cleft, lobes diamond-shaped, posterior lobes short. The disc is flat-topped, with equal lobes. The ovary lobes and disc lobes are alternate. It flowers in November.
Life Habits
Rosemary prefers warm climates. However, its growth slows during the high-temperature period in the plains of Taiwan, China. It thrives in the winter temperature without cold currents. As rosemary leaves are leathery, they are drought-tolerant.
Therefore, sandy soil rich in sand that drains well is more conducive to its growth and development. It’s worth noting that rosemary grows slowly, hence its regenerative capacity is not strong.
How to Care for Rosemary
Pot: Rosemary is a type of herb that enjoys a cold, dry environment. The pot is crucial for its growth, and unglazed pottery with good ventilation is a prime consideration. In terms of pot size, a diameter of about 20 cm is sufficient, as rosemary grows slowly and does not require too much space.
Soil: Ordinary garden soil is sufficient for planting rosemary. Add a small amount of fertilizer to the soil before planting.
Watering: In the summer when the temperature is high, water it once in the morning and once in the evening, avoiding watering at noon. In other seasons, water it once a week, and decide whether it needs water based on the condition of the pot soil.
Fertilization: Fertilize 2-3 times a year, putting well-rotted organic fertilizer in the soil at the edge of the pot, or you can apply thin but frequent doses of fertilizer. Rosemary needs enough fertilizer after flowering to ensure long-lasting blooms.
Temperature: Rosemary is a plant that tolerates cold well. In winter, it can be overwintered on a semi-enclosed balcony. It can tolerate temperatures around -5°C.
Therefore, it is not necessarily necessary to take warming measures in winter. If the winter temperature in your area is below -10°C, it is recommended to place it indoors. In the summer when temperatures are high, you should ventilate and cool down as early as possible to promote growth.
Precautions
Propagation Method
Usually, seedlings are raised in a greenhouse in early spring. Both traditional soil seedling raising and tray seedling raising can be used. If you choose soil seedling raising, prepare the seedbed first. The seedbed can be a flat bed or a small high bed, the bed soil should be finely raked, apply enough fermented base fertilizer, and water thoroughly.
Either sowing or row planting can be used. But the seeds should be sown as thinly as possible, or mixed with fine dry soil, sown on the seedbed, watered lightly, to ensure the seeds fully contact the soil.
The seeds have positive phototropism, sow the seeds directly on the medium without covering them, set up a small arch shed on the bed surface, which can both ensure the ground temperature and prevent the soil surface from crusting.
The seeds develop by the bottom water of the seedbed, but keep the soil surface moist all the time. Water again when the bud tip comes out of the soil, with the principle of frequent watering with small amounts of water.
The suitable germination temperature for seeds is 15-20 degrees Celsius. It takes about 2-3 weeks for germination. When the seedlings grow to about 10 cm, about 70 days, they can be transplanted.
For tray seedlings, mix grass charcoal and vermiculite at a ratio of 3:1 for sowing. Cover with a thin layer of vermiculite, water once thoroughly. Set up a small arch shed, and manage it the same way as traditional soil seedlings.
The difference is, after the rosemary seedlings emerge, you need to move the tray frequently to avoid the roots going through the holes at the bottom of the tray and into the ground, which would damage the roots when transplanting. The germination rate of rosemary is very low, usually only 10%-20%.
In the first year, the growth of rosemary is extremely slow. Even in the fall, the size of the plant is not much bigger than when it was first transplanted.
To produce a large number of yields, it takes 2-3 years, and the speed is very slow. Therefore, asexual propagation methods are generally used in production. But if you start cultivating from seeds, the scent is more fragrant, so which propagation method to use depends on your needs.
This is often done in winter to early spring. Choose fresh, healthy stems that have not yet fully lignified as cuttings, cut them from about 10-15 cm from the top, remove about 1/3 of the leaves below the branches, and insert them directly into the medium. Keep the medium moist, and they will root in about 3-4 weeks.
After 7 weeks, they can be planted in the open field. The minimum night temperature for cuttings is 13 degrees Celsius.
This takes advantage of the ability of rosemary stems to produce adventitious roots. Bend the branches of the plant near the ground and cover them with soil, leaving the top in the air. Wait for new roots to grow, cut them off from the parent plant to form new individuals, and plant them in the open field.
In a damp environment, root rot, gray mold, and other diseases are common in rosemary. If the rosemary plant wilts when the cultivation substrate is still damp, the plant needs to be immediately removed from the greenhouse. Common pests are red leaf mites and mealybugs. The ideal method is to use biological control.
Prevention is key. Start with good sanitation, appropriate moisture management, reasonable temperature and light, and regular observation and timely elimination of weak and diseased plants.
Industrial Value
Rosemary is a valuable natural aromatic plant that emits a refreshing aroma during the growing season and has a refreshing effect. Its stems, leaves, and flowers have a pleasant aroma, and the aromatic oil extracted from flowers and tender branches can be used as raw materials for formulating air purifiers, perfumes, soaps, and other cosmetics.
A well-known toner is made from rosemary, and it can also be used in beverages, skin oils, and laundry paste.
Medicinal Value
Rosemary has calming and brain-awakening effects and has a certain therapeutic effect on indigestion and stomach pain. It is often crushed and soaked in boiling water for drinking, 2-3 times a day, which can have a calming and diuretic effect. It can also be used to treat a variety of diseases such as insomnia, palpitations, headaches, indigestion, etc.
External use can treat trauma and arthritis. It also has the effects of strengthening the heart, promoting metabolism, and promoting blood circulation in peripheral vessels.
It also improves language, vision, and hearing impairments, enhances attention, treats rheumatic pain, strengthens liver function, lowers blood sugar, assists in the diagnosis and treatment of arteriosclerosis, and helps paralyzed limbs regain activity.
Edible Value
It has a strong astringent effect, adjusts greasy skin, promotes blood circulation, and stimulates hair regrowth. It improves hair loss (not recommended for pregnant women).
In Western cuisine, rosemary is a frequently used spice, especially often used in dishes such as steak, potatoes, and baked goods. Its taste is sweet with a pine aroma, rich in flavor, sweet with a bit of bitterness.
Flower Language of Rosemary
Memory: Rosemary is defined as a symbol of love, loyalty, and friendship, and its flower language is memory, wiping away the sorrow of memory “I will not forget the promises you gave me, please always keep your love for me, miss me, remember me.
Commemoration: Italians will throw small branches of rosemary into the graves of the deceased during funeral ceremonies, representing their respect and remembrance for the deceased. In Victorian England, the flower language of rosemary has the meaning of commemoration, symbolizing everlasting love, unwavering friendship, and eternal memory.
Legends of Rosemary
Rosemary has a rich aroma. It is said that the ancient Hungarian queen liked to bathe with rosemary, and ancient people believed that it could strengthen memory, so it is also known as the lighthouse at sea. When ships lost their way, the lost sailors could find the position of the land by this strong aroma.
Peggie was once a high school mathematics teacher, but she set aside her chalkboard and textbooks to follow her lifelong passion for flowers. After years of dedication and learning, she not only established a thriving flower shop but also founded this blog, “Flowers Library”. If you have any questions or wish to learn more about flowers, feel free to contact Peggie.
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