Learning how to propagate carnations involves discovering the three most common methods of propagation for all perennials. There are many different species of carnations, and you will find that these methods will work with all of them. Layering, seed and division are the three methods most used.
Layering a carnation involves laying the flowering stem over until it is in contact with the ground, and pinning it in place until roots form. At this point, it may be removed from the parent plant. Make certain there is a node in contact with the ground, and remove any flowers from the stem you are cultivating. The resulting child plant will be a clone of the progenitor.
Starting from Seed
Starting a carnation from seed will result in a hybrid of both parents, allowing selective breeding for desirable traits. Sow the seeds into moist potting soil indoors 4-6 weeks before the last frost date, covering with about 1/4 inch of soil. Keep seeds moist and they will begin germination in 2-3 weeks. Once danger of frost has passed, the starts may be moved outdoors and hardened off before planting into the garden.
Division of Carnations
Division of mature carnations again results in a cloned plant. Carnations will begin to overgrow themselves and produce fewer blooms after three to four years of growth. Both to propagate the plant and to continue optimal growth in an existing plant, divide in the late fall. Using a sharp garden spade, cut the matted roots cleanly into three to four sections. Leave one in place, and remove the divisions.