Grass species are an important part of vegetation all over the world and can be found in all climatic zones. Therefore, grass can be found in almost all outside scenarios. Until today, there are only few sophisticated algorithms for rendering grass in real time due to the high amount of geometrical complexity. As a result, most algorithms visualize grass as a collection of billboards or use other image-based methods, which have problems dealing with animation or physical interaction. Another disadvantage of image-based methods is that they often have artifacts when viewed from specific angles, because they are just two-dimensional images embedded in three-dimensional space. In this thesis we will introduce a fully geometric approach of grass rendering working at interactive framerates. The algorithm is very generic and is able to be adjusted and extended in various ways in order to be applicable to most scenarios of rendering grass or grass-like vegetation.