Eupatoria or water hemp is an evergreen, roundish water shrub, native to Europe, northern Africa and Asia. In Italy the Eupatorium cannabinum is found quite easily in many areas throughout the country, in wet areas with plenty of water and shade with riparian areas and deciduous forests, from sea level up to 1000-1200 meters of altitude. It produces erect stems, 100-150 cm tall, reddish, densely branched, which bear large leaves consisting of 3-5 serrated leaflets, dark green in color.
In summer at the apex of the stems large umbrella-shaped inflorescences bloom, bright pink, consisting of small flowers. Specifically, it is an inflorescence composed of several flower heads grouped in corymbs with very dense flowers, reaching 10 cm in width. The flowers, slightly perfumed, produce an oval-shaped fruit with achene, large 3-4 mm, very light, which can be transported by the wind even very far.
It is a plant that has fairly rapid and vigorous growth and tends to colonize the soil by means of very branched rhizomes.
From the underground rhizome branch up different stems, which have a height varying from 50 cm to 2 meters, a woody consistency and which can occupy a width of up to 1.2 meters. The eupatoria is used in the water gardens, although it is also present spontaneously along the water courses and in the wet areas. Among the different uses that can be made of this plant, it is noted that the dried leaves are used in herbal medicine.
The eupatorium cannabinum prefer sunny positions, but they grow without problems even in partial shade; in completely shaded places they produce a small number of inflorescences. This shrub can be planted even away from watercourses or in pots, provided you water it abundantly and regularly, keeping the soil moist.
As for the cultivation soil, the fleshy rhizomes are buried in moist, rich and loose soils, where they can have the land necessary to spread; Eupatorium cannabinum has been shown to be able to develop harmoniously in any type of soil, as long as it is humid, so it should be placed near small lakes or shallow streams, so that the soil surrounding the plant is wet or also submerged by a few centimeters of water.
Speaking of water hemp and reproduction, the eupatoria does not produce fertile seeds, therefore propagation occurs by cuttings, or by division of the rhizomes; the portions should be placed to root directly in the dwelling taking care to choose the right soil and prepare the correct mixture for the area in which the species will be planted.
Eupatoria - Eupatorium cannabinum: Pests and diseases
Speaking of Eupatorium cannabinum and diseases, aphids often attack inflorescences, covering them completely; as a result of aphid bites, attacks of fumaggine can often occur as a result of the production of honeydew by insects.