What is the primary purpose of division in plant propagation?

The primary purpose of division in plant propagation is to create more plants by separating crowns. This method specifically involves taking an existing plant and physically separating it into multiple sections, each with its own root system and shoots. This technique is particularly effective for plants that have a clumping growth habit, such as perennials, enabling gardeners to produce new plants that are genetically identical to the parent.

By dividing a plant, not only can you expand your garden or landscape with new plant material, but you also rejuvenate the parent plant, leading to stronger growth and better flowering or fruiting. Therefore, separation through division directly contributes to increasing plant numbers, which is the essence of propagation.

In contrast, the other options focus on aspects that do not directly relate to the propagation process itself. Enhancing soil fertility and reducing the need for fertilizers relate to soil management rather than plant propagation. Joining different plant parts together pertains to grafting or budding, which is a different method of plant propagation altogether.