The cornerstone of landscape design, boulders are large landscape rocks that are at least a foot across and can weigh 165 lbs per cubic foot. The two basic types of boulder, round (surface boulders) and angular (quarried boulders), come in a wide variety of colors. Boulders serve as focal points to anchor a landscape, and can also be used as natural seating. Use an odd number of boulders for an organic look. Some of our best-selling boulders are the angular Gray Cresta and the round, smooth Sierra.