NOVELTY - The method for anaerobic production and control of biogas from biomass, comprises supplying biomass to a fermenting container (2), removing the biogas under supply or effect of heat, continuously or quasi-continuously measuring the produced biogas quantity, and quantitatively introducing additionally phenol- and/or polyphenol containing- and/or anthraquinone containing plant material, as a function of the actual produced biogas quantity to the fermenting container in such a manner that the biogasification process is regularly equilibrated on a continuous gas production per time unit.    USE - Method for anaerobic production and control of biogas from biomass.    ADVANTAGE - The method provides continuous and cost-effective biogas production in a less-time consuming manner.    DETAILED DESCRIPTION - The method for anaerobic production and control of biogas from biomass, comprises supplying biomass to a fermenting container (2), removing the biogas under supply or effect of heat, continuously or quasi-continuously measuring the produced biogas quantity, and quantitatively introducing additionally phenol- and/or polyphenol containing- and/or anthraquinone containing plant material, as a function of the actual produced biogas quantity to the fermenting container in such a manner that the biogasification process is regularly equilibrated on a continuous gas production per time unit. The regular supply of phenol and/or polyphenol-containing plant material takes place via conveyor (30) of a depot, in which the plant material is brought with pre-determined granulation in advance, and then actual gas production value determined in the fermenting container is fed via the conveyer system regularly to the fermenting chamber. The depots are intended with the plant material of different granulation size in such a manner that a fast or slower effect on the fermentation process is controlled via the selection of the granulation size. The required quantity is produced by a granulation/grinding device (31) and is regularly conveyed to the fermenting container. The variance of the granulation size lies between a grinding material particle size of 0.1-5 mm. The plant material consists of sorts of knotgrass or large knotgrass (Polygonum). The sort is Igniscum (RTM: Fast growing, perennial, herbaceous plant) or Candy. An INDEPENDENT CLAIM is included for a device for the anaerobic production of biogas from biomass.    DESCRIPTION OF DRAWING(S) - The diagram shows a device for the anaerobic production of biogas from biomass.    Biomass supply line (1)    Fermenting container (2)    Controller (4)    Conveyer (30)    Granulation/grinding device. (31)