Hemp / Cannabis

Cannabis sativa

1. Identification and origin

Hemp or cannabis (Cannabis sativa L.) is an annual herbaceous species of the Cannabaceae family, originating from Central and South Asia. Throughout history, it has been cultivated for fibres, seeds, oil, medicinal purposes and, in some varieties, for the production of psychoactive compounds. In a European agricultural context, “hemp” refers exclusively to varieties with a very low content of tetrahydrocannabinol (THC), intended for industrial uses.

2. Economic importance

Industrial hemp has growing economic relevance due to its versatility: textile fibres, bioplastics, construction materials, paper, seeds for food and oil rich in essential fatty acids. In the European Union, the cultivation of cannabis for medicinal purposes is a regulated activity, requiring specific authorisations and production in a controlled environment, with full traceability and exclusive destination to authorised entities.

3. Botanical characterisation

An annual, fast-growing plant, which can reach 1–4 m in height. The stem is erect, fibrous and branched depending on the variety and the cultivation objective. The leaves are palmate, composed of 5–11 serrated leaflets. The plants are generally dioecious, with separate male and female individuals, although monoecious varieties exist. The female inflorescences produce achenes (seeds) rich in oil.

4. Soil and climate requirements

It prefers temperate climates, with good luminosity and temperatures between 15–27 °C. It needs deep, well-drained, fertile soils with a pH between 6.0 and 7.5. It is sensitive to waterlogging and benefits from good water availability in the early stages of growth. Planting density varies according to the objective (fibre, seed or biomass).

5. Main pests

• Aphids (Aphididae): sap sucking and transmission of viruses.
• Whitefly (Aleyrodidae): chlorosis and honeydew.
• Defoliating caterpillars (Noctuidae): leaf damage.
• Mites (Tetranychidae): chlorosis and reduced vigour.
• Nematodes (Meloidogyne spp.): root galls and decline.

6. Main diseases

• Powdery mildew (Golovinomyces cichoracearum, Podosphaera macularis): white mycelium on the leaves.
• Botrytis (Botrytis cinerea): grey mould on inflorescences.
• Fusarium wilt (Fusarium spp.): wilting and vascular necrosis.
• Damping-off (Pythium spp., Rhizoctonia spp.): death of seedlings.
• Hemp mosaic virus (HMV): mosaics and leaf deformations.

7. General crop management

Management includes crop rotation, the choice of certified and adapted varieties, planting density suited to the production objective, balanced fertilisation and weed control in the early stages. Regular monitoring allows early detection of pests such as aphids and mites. Adequate ventilation and the reduction of excessive humidity help to prevent powdery mildew and Botrytis.

Bibliographic references

• EPPO Global Database – Cannabis sativa.
• CABI Crop Compendium – Cannabis sativa.
• Amaducci, S., et al. (2015). Agronomic performance of industrial hemp. European Journal of Agronomy, 69, 1–9.
• McPartland, J. M. (1996). A review of cannabis diseases. Journal of the International Hemp Association, 3, 19–23.
• Salentijn, E. M. J., et al. (2015). The complex genetics of industrial hemp. Plant Breeding, 134, 1–12.