Gardens of the Cross Timbers: The Circadian Chrysanthemum

Becky Emerson Carlberg

Several state legislatures are kicking around the Sunshine Protection Act of 2021, designed to make daylight savings time permanent. This makes great sense. We won’t keep springing forward and falling back, messing up not only our circadian rhythms but those of my cats. For a week after each change, they are not into the new time regime and are either starving or…...just starving. Actually, my cats are quite adaptable to eating whenever, regardless the time!

Chrysanthemums are popping up everywhere. Big balls of color in front of houses, along walkways and throughout landscapes tell us it is fall, no matter the weather. Originating in eastern Asia and northeastern Europe, the bull’s eye for chrysanthemums is in China. Forty wild species have been identified, but varieties of the flower number over five thousand. Everybody now grows chrysanthemums it seems, and the mum is the most produced commercial flower in the US.

Have you wondered how they get the chrysanthemums to all bloom at the same time? Photoperiodism. That’s right. What is photoperiodism? Look around you. See the leaves beginning to change color? Increase in hours of darkness. Photoperiodism is the physical response of a plant to length of night darkness or dark periods. It stimulates flower production, growth of stems and roots and autumn colors followed by leaf drop.

Many flowering plants have photoreceptor proteins that sense changes in the length of darkness. Interestingly these proteins, created during daylight, combined with the circadian rhythm of the plant, somehow tells the plant how long is the darkness. Chrysanthemums, poinsettias, Christmas cacti and soy beans are “short-day” (long night) plants. If the plants are exposed to over twelve hours of light, they don’t bloom. Irises, potatoes and lettuce are “long-day” plants and bloom only when they receive over twelve hours of light.

Growers cover chrysanthemums for at least twelve hours for several weeks in late summer to stimulate autumn blooms. The mums are pinched back or sheared in spring and again late June to encourage more stem and leaf production while keeping the plants compact. As fall approaches, colder nights join in to aid bud production.

Exclude roses, tomatoes, corn, cucumbers and automatically flowering Cannabis. These plants are not thrown by periods of light and dark. They produce flowers after hitting a certain stage of development or stimulated by an environmental change, such as temperature or water availability.

Chrysanthemums were cultivated in China as far back as the 15th century BCE. The old Chinese word for the mum is ‘Chu” as in the Chinese city Chu-Hsien (Chrysanthemum City). Fifteen hundred years ago the mum appeared in Japan. They loved it. The chrysanthemum became the crest and seal of the emperor. The chrysanthemum in the seal is a 16-floret variety called “Ichimonjiginu”. Each chrysanthemum flower is composed of small flowers called florets (either disc or ray) arranged on a floral disc. The ray florets are the larger edge petals, while the disc florets dominate the center.

Many Japanese family seals have the chrysanthemum. The Imperial Order of the Chrysanthemum is the highest order of chivalry. National Chrysanthemum Day, or the Festival of Happiness, has been celebrated in Japan every September 9th since 910 AD. Oddly enough, the number 9 in Japan means “suffer”, but the double 9 (September is the 9th month + the 9th day) brings wisdom and experience.

Chrysanthemums, a member of the aster/sunflower family, came west in the 1600’s. Karl Linnaeus combined the word Chrysos (Greek for gold) with anthemon (flower). Earliest descriptions of chrysanthemums are small yellow daisy-like blooms. The chrysanthemum (annual or perennial), falls into seven main categories: exhibition, spray (multiple stems), charm (dwarf), cascade, pompon (up to 50 flowers per plant), rubellum (woody perennials) and garden (bushy with clusters of flowerheads).

Hybridizers have gone wild, developing flowers in red, yellow, orange, white, purple, green, brown and pink or even multiple colors on the same flower. Chrysanthemum flower heads currently come in twelve types: single, spider or quilled blooms, anemone types, pompons, spoon, and thistle-like. The Japanese cultivate as a bonsai the Nippon Daisy ‘Nipponanthemum nipponicum’, a perennial formerly classified as a chrysanthemum. This ‘mum’ can live beyond 70 years.

Mums are easy to grow. Moist, well-drained soil and sun. Flowers last 2 to 3 weeks. Plant centers die out so every few years divide and replant late fall or early spring. The plants are sources for pyrethrum, a natural insecticide. The stems of the leaves are sweet and crunchy. The leaves, steamed or boiled, can be eaten as greens or added to soups. The entire plant reduces indoor air pollution.

Autum mums.

Thank the Enomoto brothers in Redwood City, California for cultivating the first US chrysanthemums in 1884. Sadakasu Enomoto in 1913 shipped a carload of Turner chrysanthemums (perennials) to New Orleans for All Saints Day.

In New Orleans, the chrysanthemum is put on gravestones. Austria and other countries in Europe consider the chrysanthemum a death or grave flower. Never give a chrysanthemum as a hostess gift. On the first official Armistice Day in 1919, the president of France ordered flowers put on all French war memorial graves. Since the chrysanthemum was in full fall bloom, over 30,000 mums were distributed. They became known as the widow’s flower.

The eleventh hour of the eleventh day of the eleventh month was declared Armistice Day in 1919, signifying the end of World War I. In 1938 Armistice Day became a US national holiday. After the end of the Korean War, President Dwight D. Eisenhower officially changed the name from Armistice Day to Veterans Day in 1954. In 1971 Veterans Day was moved to the fourth Monday in October to join all the other Monday holidays. In 1975 President Gerald Ford returned Veterans Day back to November 11th because of its importance. This past November 11, 2021, tribute was paid to all American veterans living or dead. That day also marked the 100th anniversary of the Tomb of the Unknown Soldier, dedicated by the Army on Nov. 11, 1921.

Becky Emerson Carlberg, graduate of Oklahoma State (Plant Pathology) is a teacher, artist, writer as well as certified Oklahoma Master Gardener and Master Naturalist. Contact her at