Climate and water requirements

Hemp is a rather robust and resilient plant that can cope well with challenging situations (Desanlis et al., 2013). Worldwide, hemp varieties are categorised into three main groups: European, American, and Asian varieties. Some cultivars are adaptable across multiple continents. In Europe, specific varieties have been developed in three regions: North-West Europe, Mediterranean Europe, and Central-East Europe. Certain varieties are adapted to continental climates with harsh winters and humid summers, while others are suited for Mediterranean conditions marked by dry summers. Some varieties exhibit adaptability across multiple regions. It is crucial to assess a cultivars suitability for the local environment in terms of climate, soil, and cultivation practices before selection (van de et al., 2023). The optimal temperature for hemp vegetation is around 19 and 25 degrees and should not fall under -5 degrees. (Desanlis et al., 2013)

In general, hemp varieties are classified into early and late flowering types, which determines cultivation and harvesting methods. Flowering timing is influenced by the cultivar, altitude, and climate rather than the sowing time. Early harvests are preferred for textiles and flower contents, while late harvests are optimal for seed extraction and high fibre yield (van den Oever et al., 2023).

Water supply is key for the success of the crop throughout the vegetation period. Especially in the period of rapid longitudinal growth, hemp has a high-water requirement. Hemp for fibre requires at least 200 to 300 mm of precipitation during the growing season (TFZ, 2020) and this plant mobilizes between 300 and 500 l of water for 1 kg of dry matter (Desanlis et al., 2013).