Harvesting of flax and hemp fibres in normal time in autumn often meets with special problems in the Nordic circumstances. These are mainly due to the short growing period and the cold and rainy period in autumn. The risk of formation of mold spores inside the harvested fibre plant bales is obvious (1). Even though the bales are dried in bale driers there is enough time for the molds to destroy the quality of the raw material. This is caused by both the slow drying process and the high microbiological activity of the moist material (3). This is the reason why the new Dry-line-method (2) is under research. Briefly the dry-line-method means: harvesting the seeds in autumn which are at that time the driest parts of the plant harvesting the straw in spring which is the driest time of the year benefit from the good friction and processing properties of dry plant material The frost affects fibre plants in Northern circumstances. In springtime the temperature is changing daily above and below the zero. This leads to the enlarging movement which is resulted from the frozen water and which is varying in different plant cell structures. When this takes place repeatly several times the movement also loose the bast fibre from the stem. Also the fibre yield was measured after processing raw material with different methods. The demand for energy when processing of the plant material was being reduced drasticly when compared to unretted or dew retted material. For the second, the yield of the processed fibre from the plant raw material was higher compared to material which was not frozen. The latter is due to both the higher loss of shives before and during the processing as well as the better separation of fibre and shives during and after the processing.