Chrysanthemums, commonly known as mums, are flowering plants celebrated for their vibrant, late-season blooms that signal the arrival of autumn. These popular garden plants are botanically capable of producing seeds, as seed production is the natural reproductive method for most flowering species. However, obtaining viable seeds from a typical garden mum and expecting a plant identical to the parent is challenging. The specific varieties widely available in the commercial market present significant hurdles to successful seed collection and cultivation.
Why Seed Collection is Uncommon
Seed collection from garden mums is generally discouraged due to plant genetics and commercial breeding practices. Most showy, uniform mums purchased commercially are complex hybrids, often sterile cultivars, resulting from cross-pollination between distinct parent plants. When seeds are collected from a hybrid, the resulting offspring will not be a genetic copy of the parent flower. This is known as “not breeding true,” meaning the seeds revert to the characteristics of one of the original parents or display new, less desirable traits. This genetic variability makes seed saving unreliable for gardeners hoping to clone their favorite varieties, and some heavily hybridized cultivars may produce sterile seeds or a minimal number of viable seeds due to their modified floral structure.
Identifying and Collecting Mature Seeds
For the few open-pollinated or heirloom mum varieties that produce stable offspring, collecting seeds requires careful timing. Wait until late fall or early winter, after the flowers have faded and the petals have completely dried out. The seed is located in the dried central disk of the flower head, not the petals. A mature seed head will appear brown, dry, and brittle, indicating the small seeds within are fully developed and ready to drop.
To harvest, carefully clip the entire dried flower head from the plant. Ensure the heads are completely dry before separating the seeds, as moisture can cause mold and ruin viability. Gently crush the dried flower heads over a sheet of paper to release the tiny, often black or brown seeds from the surrounding chaff. Allow the separated seeds to air-dry for two to three days in a warm, dry place away from direct sunlight to reduce moisture content. For long-term storage, place the seeds in a labeled, airtight container, such as a paper envelope or small jar, and store them in a cool, dark, and dry environment, where they can remain viable for two to three years.
Alternative Propagation: Cuttings and Division
Since seed starting is unpredictable, the most reliable methods for propagating chrysanthemums involve vegetative propagation, which guarantees a genetically identical clone of the parent plant.
Cuttings
Taking soft-wood cuttings is an effective technique used by commercial growers and home gardeners. This involves clipping a non-flowering, non-woody shoot, typically two to four inches long, from the plant in late spring or early summer. The base of the cutting is dipped into a rooting hormone to stimulate root growth before being inserted into a sterile, well-draining medium. These cuttings usually root within four to five weeks, producing a new plant that will have the exact flower color and growth habit of the original mother plant.
Division
Clump division is another simple and effective method, especially for rejuvenating mature plants that have become woody or less vigorous in the center. This is best performed in the early spring when new growth is just beginning to emerge. The entire root ball is dug up and split into three to five smaller sections, each containing healthy roots and several new shoots. Replanting these divisions immediately creates new plants and helps to reinvigorate the parent clump, ensuring a consistent and robust display for the upcoming fall season.