Aromatic plants: everything about the holy thistle | Cultivation and Uses

The holy thistleknown by the scientific name of Centaurea benedictais a plant rich in history, imbued with cultural and botanical meaning. Belonging to the vast family of Asteraceaeone of the largest and most diversified in the plant kingdom, has in its common names, such as “holy thistle” or “blessed thistle”, a clear link with the religious world: the holy thistle was in fact very widespread in monasteries, where it was widely used due to its medicinal properties.

Botanical description of the holy thistle

The holy thistle is an annual plant that can reach variable heights, from 10 centimeters up to a meter, depending on environmental conditions. The variable growth is accompanied by a delicate, fistulous root, which provides the necessary support for the stems, which are angular and branched. The branches have reddish-grey tones and are covered with light glandular hair, a typical characteristic of many plants of the Asteraceae family.

The leaves are also notable: the basal ones, up to 30 cm long, have considerable dimensions, with shapes that can vary from lyrate to pinnate, adorned with triangular lobes and teeth that end in thorns, almost as if to suggest innate resistance. The shorter cauline leaves run along the stem, completing a complex but fascinating architecture.

The flowering of the holy thistle is a spectacle of shapes and colors: the flower heads, surrounded by the upper leaves, develop into yellow inflorescences veined with purple, surrounded by thorny bracts. The flowers themselves, hermaphroditic and fertile, reveal a well-orchestrated reproductive mechanism, which relies on entomogamous pollination, i.e. through insects such as butterflies, both diurnal and nocturnal.

Variety and distribution of the holy thistle

Centaurea benedicta is not a particularly demanding species in terms of habitat. It prefers Mediterranean areas, finding its ideal soil in the plains of Central and Southern Italy, especially in the Tyrrhenian areas, it can thrive up to around 800 meters above sea level, easily adapting to loose, deep and fertile soils.

What is striking about the holy thistle is that it belongs to a vast and varied group: the Centaurea genus in fact has over 700 species, of which around a hundred are spontaneous in Italy. Despite this diversity, the holy thistle stands out for its rigid bracts and pinnate spines, which contribute to a unique and distinctive morphology within the group.

The winter flowering of the holy thistle

One of the most intriguing aspects of the holy thistle lies in its ability to flower even during the winter. In a period in which many plants are preparing for vegetative rest, this species challenges the cold and adversity, demonstrating singular and unexpected vitality. The yellow flower heads, often stained with delicate purple veins, stand like small suns in an otherwise bare landscape, a characteristic that makes Centaurea benedicta a precious resource in winter gardens, especially for anyone who wishes to enrich the green space with a pinch of color during the grayer months.

The flowering of the holy thistle begins already in late autumn and can continue until early spring, depending on climatic conditions. This peculiarity increases its ornamental value, while also attracting numerous pollinating insects which, in mid-winter, when food is scarce, find the holy thistle a source of vital nourishment.

Cultivation of the holy thistle

Growing holy thistle is not particularly difficult, as long as you follow some fundamental rules. The plant requires good exposure to sunlight, therefore preferring well-lit and sunny positions, although it can tolerate some partial shade, especially in the hottest hours of the day.

As for the soil, it is important that it is well drained, since water stagnation can damage the delicate root of the plant: a loose and fertile soil, possibly enriched with organic substances, will guarantee optimal growth. Sowing can take place in autumn or spring, even better if carried out at the beginning of autumn, so as to be able to take full advantage of the excellent winter resistance of the plant.

Pot cultivation of holy thistle

If you don’t have a garden, you can still enjoy the beauty of the holy thistle by growing it in a pot. In this case, we recommend using containers of at least 16 cm in diameter, in order to offer the roots the space necessary to develop, while as regards the soil, this must be well drained, so add a layer to the bottom of the pot of expanded clay, or gravel, to avoid stagnation.

How to water the holy thistle

The irrigation phases must be moderate: during the winter it will be enough to water the plant once every 10-15 days, making sure that the soil dries completely between one watering and the next.

How to fertilize holy thistle

The holy thistle is a plant that does not require excessive fertilization. A slow release fertilizer, applied in early spring, will be sufficient to ensure lush flowering. Pay attention to attacks by parasites, especially aphids and mites, which can infest the plant, especially if grown indoors.

Diseases and parasites of the holy thistle

As mentioned, the holy thistle can be subject to infestations by insects, in particular aphids and mites, which attack the leaves and stems. To prevent such problems, it is advisable to regularly monitor the plant and, if necessary, resort to natural treatments based on neem oil or insecticidal soap.

Fungal diseases, such as powdery mildew, can also affect the holy thistle, especially in humid environments: in these cases, the use of specific antifungal products may prove necessary.

The holy thistle in cooking and herbal medicine

The holy thistle also boasts a long use in cooking and herbal medicine. The shoots and younger leaves can be eaten raw in salads, or cooked in stews and soups, giving dishes a slightly bitter flavour. In the past, a bitter liqueur was made from its leaves, appreciated for its digestive properties.

In the herbal field, holy thistle is known for its purifying and tonic virtues. It is used in herbal teas and infusions, especially to stimulate the appetite and facilitate digestion.