A truly rewarding aspect of landscape painting is to enjoy the finer details added to the canvas, once the "basic" painting is completed. By the term "basic" I mean that the composition is complete, pastel has been carpeted throughout the canvas, lighting is looking right, values and colors are accurately portraying the subject, and perhaps best of all, the artist can now part with his or her reference photograph!
Below is a portion of "Birch Ballet" focused on the foreground grassy area. A darker green pastel is used to add strokes of shade behind the grasses. The same dark pastel can be used horizontally to convey breaks in the grasses, such as a blade of grass that bends or an area to convey blotches of lighter foliage. Although I instruct my students to lay down the dark values first, there is still room to add dark for effect like this later on.
Be careful that you do not add a blade of grass (in this example) using the dark pastel, unless you have a grassy area that sits in the shade. As a shade tool, my dark pastel can also be used to break up areas that appear too clustered with the same foliage.
Here is the area of detail where I applied my "shade tool:" A tortillion or the edge of a hard pastel can be used to help smooth out the pastel grains.