The industrial hemp plant "Cannabis sativa" is a source of plant fibres for both garment textile and bio-composites applications. After harvesting, the plant stems are laid out on the ground and colonised by microorganisms (bacteria and fungi) naturally present in the soil and on the stems. By producing hydrolytic enzymes that degrade the plant wall polymers, the natural cement that binds the fibre bundles together is removed, thus facilitating fibre extraction (retting process). Retting is then a key process in fibre extraction as it affects mechanical extraction performance and intrinsic fibre properties. In order to promote the production of high-quality fibres, it seems necessary to extend the production of these fibres to other areas where hemp is not currently grown, more specifically in Southern France (Occitanie Region). However, field retting is highly dependent on pedoclimatic conditions which can lead to inconsistent fibre quality. Therefore, the aim of this work is to investigate the biological mechanisms involved in the retting of hemp stems in order to carefully monitor this process in a dry and warm climate. The evolution of the plant cell wall and the biochemical composition of fibres was firstly investigated. For this purpose, the stems were subjected to different assessments during retting: colour, morphology (optical and scanning electron microscopy) and biochemical composition. This work reveals that field retting leads to a change in stem colour from light green to black. The removal of cementing compounds (pectic middle lamella) by microorganisms results in the separation of the fibres to obtain smaller fibres bundles. In parallel, the temporal dynamics of both microbial diversity and enzymatic activities are evaluated. The correlation between retting microbiology (bacterial and fungal communities) and intrinsic characteristics of fibres will be examined in order to identify key criteria for controlling retting and subsequently obtaining high value fibres with homogeneous properties.