Typically you get better results with smaller brushes to control where you want the foliage to show up. However, another option is to adjust the density of both the paint (top of the foliage mode) and the density within each individual mesh you are using. This affects how much of a specific mesh is placed within the area you have designated. Specifically if you alter the density and radius within the specific meshes, you are determining the amount of specific meshes and how much space must be between individual meshes. You can find a lot of information about our foliage system here: