For darker block shading, use the side of the pencil with pressure. Build up shades from light to dark, so start with minimal pressure and slowly add until you achieve the desired shade.
Or if you wanted to shade using texture, you could try cross-hatching; a bigger number of closer lines = darker area. Using less lines, spread further apart will make the shading lighter.
This works also when you shade using horizontal lines or using your pencil in a circular motion.
Use a test piece of paper to try out each of the techniques individually and using different amounts of applied pressure to make a scale like so:
Then, once you've tried out the different motions, apply to the background. Generally, the closer background will be more in focus, so here it will be more detailed, where in the distant background, details needn't be exact.