A method and an apparatus for producing biogas from organic matter including a container (1) which is charged with fermentation substrate by a delivery system (13). At least one stirring mechanism (2) is arranged in the container. The feedback value of at least one measurable variable is detected and transmitted to a control unit (4). A reference variable is also provided to the control unit. The control unit calculates the deviation of the feedback value from the reference value, and actuating variables which modify the power input of the stirring mechanism and/or the composition of the container contents and/or the flow behavior of the container contents are adjusted as a function of the deviation.