Layering, division, and separation are all methods of __________ propagation.

Layering, division, and separation are all methods of asexual propagation, which involves reproducing plants without the need for seeds. In asexual propagation, a new plant is produced that is genetically identical to the parent plant, which is a key characteristic.

Layering involves encouraging roots to form on a stem while it is still attached to the parent plant, allowing it to establish itself before being separated. Division is the process of separating a plant into multiple sections, each with its own roots, allowing each section to grow independently. Separation, often used with bulbs or tubers, involves removing individual parts from a parent plant to produce new plants.

Other methods listed, such as seed propagation, involve sexual reproduction, where the genetic material from two parent plants combines. Grafting involves joining two different plant parts to grow as a single plant, which does not fall under the same category as layering, division, and separation.