What to know about Calendula officinalis (pot marigold) before using it medicinally

Calendula officinalis, commonly known as pot marigold, is a herb renowned for its impressive array of health benefits, including its potent anti-inflammatory, antimicrobial, and antifungal properties, which make it an effective treatment for wounds, skin irritations, and infections.

This versatile herb is also a favorite among gardeners due to its ease of growth and adaptability to various environments, requiring minimal care and making it an excellent choice for beginners. Botanically, Calendula officinalis belongs to the Asteraceae family and is characterized by its bright orange and yellow flowers, which contain sesquiterpene lactones, a group of compounds responsible for its medicinal properties.

The ancient Greeks and Romans were among the first to utilize Calendula officinalis for its therapeutic purposes, and it has since been used in various forms throughout history, including in traditional Chinese medicine and in modern herbal remedies.

This article explains the medicinal, horticultural, botanical, and historical aspects of Calendula officinalis.

What are the medicinal properties of Calendula officinalis?

Calendula officinalis helps with wound healing, skin irritations, and inflammatory conditions due to its antimicrobial, anti-inflammatory, and antiseptic properties. Its extracts are used topically to promote tissue repair, reduce pain, and prevent infection. It also helps with skin conditions such as eczema and acne.

The medicinal properties of Calendula officinalis are attributed to its active constituents, including flavonoids, triterpenoids, and carotenoids. These compounds exhibit strong antioxidant, anti-inflammatory, and antimicrobial activities, which contribute to the plant's therapeutic effects. The exact composition and proportions of these constituents may vary depending on the plant's source and preparation method.

The parts of the Calendula officinalis plant most used for medicinal purposes are its flowers, leaves, and stalks. The flowers are rich in flavonoids and carotenoids, while the leaves and stalks contain more triterpenoids. These plant parts can be harvested fresh or dried for later use in infusions, tinctures, or salves.

When used improperly, Calendula officinalis may cause skin irritation or allergic reactions, particularly if used in high concentrations or on sensitive areas. Excessive use may also lead to gastrointestinal upset, nausea, or vomiting. Prolonged use without proper monitoring may interact with other medications or worsen underlying conditions.

To ensure safe use of Calendula officinalis medicinally, individuals should consult with a healthcare professional before using it, especially if they have allergies, underlying medical conditions, or are taking medications. Pregnant or breastfeeding women should also exercise caution and follow guidelines from a healthcare professional. Doses and preparation methods should be carefully followed to avoid adverse effects.

What are the horticulural aspects of Calendula officinalis?

Calendula officinalis grow in full sun to partial shade in well-drained soil with a pH between 6.0 and 7.0. Temperatures between 15°C and 30°C (59°F and 86°F) promote healthy growth. Average annual rainfall of 60-80 cm (24-32 in) is sufficient for the plant's needs.

For optimal growth, sow calendula seeds 1-2 cm (0.4-0.8 in) deep in the soil, 2-3 times thicker than a usual sowing depth. Space plants 30-40 cm (12-16 in) apart, and keep the soil moist during the first few weeks after sowing. Calendula is a warm-season crop, and it thrives in areas with moderate climates.

To harvest calendula flowers, wait until they are fully opened and bright yellow. Cut off the stems when the flowers are in full bloom, leaving about 2.5 cm (1 in) of stem attached. Harvest flowers regularly to encourage the plant to produce new blooms. Drying or pressing flowers helps preserve them for later use.

Common pests affecting calendula include aphids, whiteflies, and spider mites. Fungal diseases such as powdery mildew and leaf spot may also occur due to high humidity, overwatering, or poor air circulation. Regular monitoring and good garden hygiene practices can help prevent or minimize the impact of these issues.

What are the botanical aspects of Calendula officinalis?

Calendula officinalis is a perennial herbaceous plant belonging to the Asteraceae family. Its stem is erect, herbaceous, and hairy, growing up to 0.5-1.5 meters in height. The leaves are lanceolate and alternate, measuring 4-10 cm in length.

Calendula officinalis is classified within the Asteraceae family, with the subfamily Calenduloideae and the tribe Calenduleae. The genus Calendula is distinct from other related genera, characterized by the presence of ligulate florets and absence of disc florets. The plant's nomenclature is based on its botanical and historical significance.

The Calendula officinalis plant exhibits various variants, including 'Flore Pleno', 'Aurea', and 'Alba'. These variants differ in flower color, petal number, and leaf shape. Some variants, such as 'Flore Pleno', display double flowers, while others, like 'Aurea', have yellow-colored leaves.

Calendula officinalis is native to the Mediterranean region, but its cultivation and distribution have led to its presence in many parts of the world. The plant thrives in temperate and subtropical climates, with optimal growth conditions in dry to moist soils and full sun to partial shade.

The life cycle of Calendula officinalis begins with germination, which typically occurs within 2-4 weeks after sowing. The plant blooms within 60-70 days after sowing, with flowers opening in the morning and closing in the evening. Flowering continues until frost, after which the plant dies back, preparing for winter dormancy.

What are the historical aspects of Calendula officinalis?

Calendula officinalis is a plant with a long history of medicinal and culinary uses. In ancient Rome, it was used to make a dye for fabrics, while in medieval Europe, it was employed as a treatment for wounds and burns. It was also used as a food coloring and a flavoring agent.

In ancient Greek and Roman mythologies, Calendula officinalis was associated with the goddesses of fertility, Demeter and Ceres. The plant was also linked to the Roman goddess of the harvest, Flora. In some cultures, it was believed to have purifying properties, associated with the gods of water and purification.

Calendula officinalis has been imbued with symbolic meanings across various cultures. In ancient Greece, it represented the sun and the life-giving power of the sun god, Helios. In medieval Europe, it symbolized the Virgin Mary, representing purity and protection. It was also associated with love and loyalty.

Historical texts have documented the uses and properties of Calendula officinalis since ancient times. The Greek physician Dioscorides wrote about the plant's medicinal properties in his book "De Materia Medica". The Roman naturalist Pliny the Elder also mentioned the plant's use in his book "Naturalis Historia".

Historical artifacts featuring Calendula officinalis include ancient coins from ancient Greece and Rome, depicting the plant as a symbol of fertility and abundance. Medieval manuscripts and illuminated texts also feature illustrations of the plant, highlighting its medicinal and culinary uses.