Calendula officinalis L.
Annual or perennial plant with striated stems covered with thin, tiny hairs. The leaves are alternate, without petiole, and whole or slightly toothed. The flowers are gathered in yellow-orange flower heads: the center ones are tubular, while the peripheral flowers are ligulate and longer than the bracts of the involucre. The fruit is an achene. The root is fusiform and provided with fibrous radicles. For ornamental purposes, varieties with ligulate or full flowers have been obtained by genetic selection. Furthermore, the genetic improvement has made it possible to obtain other varieties, such as: double-flowered varieties, varieties with various tones or shades from yellow to red, and varieties with dwarf to elongated stalks.
There are numerous species of the Calendula genus, even if, however, Calendula officinalis is the species that is used most for medicinal purposes. One must be careful not to confuse it with the genus Tagetes minuta, also called Mexican marigold, or with Tagetes erecta, called African marigold.
HERBAL TEA CUT
The freshly picked flower heads are dried in the shade or in dryers at a temperature no higher than 40°C. To optimize time, it is possible to do a drying at a higher temperature (80°C) for short periods. The conservation must happen in dry and dark places to avoid the loss of color in the flower and, therefore, the content of flavonoids and carotenoids.
The parts of the plant that are used are the fresh flower tops with about 15cm of stem. They are put to macerate in a 55-proof hydro alcoholic solution for about a month, mixing the solution daily. Caution: the drug/extract relationship is not 1:10 but 1:20 because of the higher content of water present inside the flowers.
Once the flower heads are dried they are put in a hermetic glass container and a vegetable oil is added (usually extra virgin olive oil) in a 1:10 ratio. Recall that in the home self-production it is not necessary to have the exact relationships. It’s important that the plant is submerged completely in the oil used. The flower heads are left to macerate in the sun for at least 3 weeks. The infusion is filtered and conserved in a small, dark, glass bottle away from light and sources of heat.
Climate and soil:
It is a quite rustic plant. It requires mild temperatures, fresh, well drained soils rich in organic substance and a good sun exposure, to facilitate the production of flavonoids and carotenoids.
Planting and propagation:
Propagation is usually carried out by seed, sowing in April/May or in Autumn in milder climates on a finely worked soil, using about 2-3 kg /hectare of seed.
It is also possible to transplant the seedlings, obtained in paper-pot a couple months before the sowing. But this technique is not always economically suitable.
A high density is not recommended because it is possible to obtain a greater amount of flower heads, but smaller and overall with a lower yield.
The final density should not exceed 6 plants/m².
A smaller amount of nitrogen is used to avoid an excessive development of the leaves, which would result in a reduction of the development of the flowers.
Irrigations can be necessary to help the seedlings take root and to ensure the vegetative restart.
Irrigations during the flowering are not recommended, to preserve the quality of the flowers.
Generally several hoeings are carried out in the inter-row, to control the growth of weeds.
The crop is very sensitive to fungal diseases such as oidium; in case of infestation the harvesting is stopped and no treatment is performed.
Marigolds flower gradually (scalar flowering): the flowering starts around late May and last until September. As a consequence the harvesting is prolonged too.
The harvesting is carried out manually in small plots, removing only the flower, without the stalk. Manually it is possible to harvest about 10-15 kg of flowers/hour.
The harvesting in large cultivations can be mechanized using the same machines used for chamomile.
The yield in fresh flower heads is of about 10-15 tons/hectare, which corresponds to 2-3 tons/hectare of dried product.
Parts of the plant used:
Fully bloomed flowering heads, without the stalk.
Properties and uses:
The flower heads are used as food or cosmetic coloring, to give an orange hue.
For internal use, thanks to its emollient, anti-inflammatory, antiseptic and antiviral (for example against flu and herpes virus) properties marigold is used to treat menstrual irregularities, colds and pharyngitis.
The herbal tea is recommended against abdominal swelling, stomach and liver conditions.
Many studies confirm the effectiveness of marigold-based extracts on bile secretion.
Herbal teas and tinctures are effective, when used for gargles, against mouth and throat inflammations.
To treat onychosis, the fingers are soaked in the herbal tea for 10 minutes.
For external use it is part of the formulation of creams and ointments for dry, chapped, and sensitive skin.
It has vasodilator properties on peripheral circulation and can be useful in case of reddened skin, heavy and tired legs, varicose veins and hemorrhoids (it reduces the inflammation of skin and mucous membranes and local tissues tension.)
Topical use improves skin elasticity and makes skin more resistant to mechanical damage.
It is also effective in case of erythema, dermatosis, acne, ulcer, and hyperkeratosis.
It is often recommended for skin injuries and burns thanks to its healing properties.
Marigold ointments are effective in preventing radiotherapy–induced dermatitis.
The plant also has antimicrobial and antiviral properties.