Thymus vulgaris L.
Lamiaceae (sin. Labiatae)
History and origins
The name derives from Greek thymos (courage, audacity); Greek and Roman women embroidered thyme into their husbands’ clothes when they went off to war. This tradition continued into the following centuries and was still practiced in the Middle Ages.
The Romans used thyme to flavor food, wine, and cheese. Due to its antibiotic properties, thyme was also used in the conservation of foods and as a disinfectant.
The essential oil (1.0 – 2.5% of dry matter) has thymol (up to 55%) as the main active ingredient, also in lower quantities; geraniol, linalool, terpineol, carvacrol, borneol, and cymene.
The highest concentration of active ingredients is found in the basal leaves before flowering.
Thyme has antibacterial, anti-fungal, and antiseptic properties: its disinfectant abilities are 25 times greater than phenol and it is less toxic; it is used as a remedy for diseases of the digestive tract (stomatitis, gastritis, ulcers, colitis…), the respiratory system (as a balsam and an expectorant), urinary tract (cystitis, urethritis…), skin (dermatitis, psoriasis, boils…), central nervous system (antispasmodic, analgesic, sedative but invigorating…).
Thyme is widely used in cooking.
Diffusion and importance
In Italy the cultivation is spread over 20 hectares, mainly in Piedmont and Emilia-Romagna.
The main producers of thyme are France, Greece, Spain, Portugal and the United States of America.
Biologic type: Thyme is a perennial evergreen.
Stem: erect, quadrangular section, very branched, 10-60 cm tall, and tends to become woody after 4-5 years, forming dense compact bushes.
Leaves: opposite, laceolate, tomentose, and gray-green.
Inflorescence: spike-like situated at the leaf joints with white or pink flowers; in Italy, it blooms roughly from May to July.
Fruit: tetra-achene; 1000 achenes (“seeds”) weighing 0.2-0.3 g, germination ability: 2-3 years.
Climate and soil requirements
Thyme prefers warm and sunny climates. It is resistant to drought and frosts, but does not tolerate cold wet winters.
Thyme adapts to different types of soil but prefers loose calcareous soil.
Fundamentals of cultivation techniques
Thyme is propagated using seeds, herbaceous cuttings and plant division.
Sowing can be done directly in the field or in seedbeds for subsequent transplant. Direct sowing in the field (5-6 kg/ha of seed) is rarely done.
Transplantation, which is the most common planting technique, is done in the fall or in the spring (April-May).
Propagation by cuttings is done in spring or late summer.
The planting distance between the rows is 50-70 cm and between the plants within the row 25-35 cm, for a density of 5-8 plants per m2.
Thyme is grown for about a four-year period, after which the plant tends to become woody.
Thyme has low nutritional requirements, but adequate nitrogen fertilization (70-80 kg/ha per year) promotes vegetative growth; nitrogen fertilizers should be distributed gradually to vegetative growth and after the collection of cuttings. The application of a basal dressing of 50-60 kg/ha of phosphorus and 100-120 kg/ha of potassium is also recommended.
Irrigation in our areas is required after transplantation to promote the rooting of seedlings, and during the growing season to encourage vegetative growth and sprouting after cutting.
The crop benefits from hoeing between the rows for weed control and for the aeration of the soil, and from light hilling to promote the rapid re-growth of buds and to protect the basal part of the plant from freezing.
For herbal use, harvesting is done in early bloom, while for the extraction of essential oil, harvesting is done during full bloom.
During the first year of cultivation, only one cut is made at the end of summer, while in the years following, two cuts are made; one in May-June, and one in September-October.
The yield depends on many factors (climate, availability of water and nutrients…): thyme produces an average of 4.5 t/ha of fresh product which is equal to about 1-1.5 t/ha of dry leaves and flowers; the fresh product contains 0.5-0.8% of essential oil with an oil yield of about 20 kg per hectare.