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Chrysanthemums: How to Plant and Grow Mums | The Old Farmer's Almanac

Chrysanthemums

Botanical Name
Chrysanthemum x morifolium, C. rubellum
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Sun Exposure
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How to Grow Mums aka Chrysanthemums

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Chrysanthemums or “mums,” the quintessential autumn flower celebrate the season in jewel colors: Yellow, lavender pink, purple, red, bronze, orange, and white. Each bloom consists of tiny flowers called florets. The leaves are blue-green. Bloom forms range in size from pincushion petite to giant spiders, and there are hundreds from which to chose. Discover how to plant, grow, and care for these colorful members of the daisy family!

About Mums

The chrysanthemum was first cultivated in China as a flowering herb back in 15th century B.C. Based on early illustrations, it appeared as more of a daisy-like flower. Since then, the mum has been bred in so many shapes, sizes, showy styles and a multitude of colors that it doesn’t always resemble its humble beginnings.

mum-daisy_full_width.jpeg
Credit: Mums.org

According to the National Chrysanthemum Society, “the genus Chrysanthemum once included more species, but was split several decades ago into several genera, putting the economically important florist chrysanthemum in the genus Dendranthema.  The placement of the florist chrysanthemum in this genus was very contentious.  A ruling of the International Code of Botanical Nomenclature in 1999 changed the defining species of the genus Chrysanthemum to C. indicum, giving the florist mum back its prized generic name.” The National Chrysanthemum Society divides bloom forms into 13 classes.

Decorative Mums

Treat mums sold in garden centers in autumn as annuals. They are decorative gift plants, which are not bred to be hardy. It’s their color, size, and form that are prized in the fall garden. Do not try to overwinter them. They are not bred to be hardy. If put in the ground in late fall, many won’t make it through a cold winter.

Planting

Select a planting site in full sun with well-drained soil. Mums do not like standing water and will quickly rot if left too wet. Prepare the soil to improve drainage and nutrients by adding aged manure or compost to the soil. Mums are heavy feeders.

Plant mums away from trees and big shrubs, but dark at night. Or, shade the plants every night from light sources, such as street and security lights. Bloom time is determined by day length (12 hours or less), and buds start forming then. Plants that receive light at night will be slow to bud.

When to Plant Mums

  • Mums are hardy perennials best planted in early spring. 
  • Start mums indoors from seed 6 to 8 weeks before the last spring frost date.

How to Plant Mums

  • Mums generally grow to a width and height of 1 to 3 feet. Set them 18 to 36 inches apart, depending on their expected size at maturity.
  • Mums need good air circulation.
  • Plant mums in the ground at the same depth they were at in the pot. If planted too low, water can gather around the base and rot the stems. Watering keep evenly moist.

 

Growing

To create a busier mum plant, pinch back the stems. When new shoots reach 3 to 4 inches tall, pinch off the top, leaving 2 to 3 leaves on the shoot. This will create a bushier plant. Continue pinching every 2 to 3 weeks until mid July, when buds develop. On the West Coast, stop inching in early July. In the South, stop in early August. Stop fertilizing when flower buds emerge. 

Southerners enjoy the colorful displays of blooming mums twice yearly because the equal days and nights of temperate weather that spur mums to bloom arrive in spring and fall. Northerners must be satisfied with one show, in autumn.

  • Mums are heavy feeders. Fertilize monthly by sprinkling a balanced fertilizer (10-10-10) around the plant. 
  • Maintain good air circulation around plants.
  • Add mulch around the mum to conserve soil moisture and to keep weeds out.
  • Soak the soil deeply when watering. Avoid watering the leaves.
  • For big flowers, pinch off all buds except the largest and strongest on each stem. Remove secondary buds farther down the stem as they develop, too. Switch to a high-nitrogen fertilizer after buds have set.
  • If flower size does not matter, stop fertilizing in mid-August.
  • After the ground has frozen, spread 4 to 6 inches of mulch around the plant.
  • Do not cut back mums in fall. The dead growth insulates the roots. Cut off the dead stems and leaves when you see the first green shoots in spring.

 

pink chrysanthemums

Overwintering Mums

In particularly cold areas (Zones 4 and colder), it’s easiest to treat mums as annuals. However, you can overwinter plants in a basement or dark, cold closet. Pot up plants after the first frost in the fall, capturing as many of the roots as possible. Leave the foliage on the plants until spring. In USDA Hardiness Zones 5 and warmer, perennial chrysanthemums can be kept outdoors (in the ground) through the winter.

  • Water well and keep the roots damp. Check pots weekly.
  • In spring, gradually introduce the plants to light. Set them out after the last killing frost.
  • Add 4 to 6 inches of mulch around the plant after the ground has frozen in the fall.
  • Don’t cut back mums when tidying up flower beds in the fall. The dead growth insulates the roots.
  • Cut off the dead stems and leaves when you see the first green shoots emerging in the spring.

Dividing Mums

Every 2 to 3 years, divide the mum when new growth appears in the spring. Use a knife cut out the old central portion of the plant. Discard it. Cut the remaining portion into sections. Each section should have several shoots and good roots. Replant these sections.

Harvesting

Cut flowers for arrangement when they are nearly or fully open. Remove lower leaves that would be in water. Leaves submerged in water will rot. Change the water in the vase every couple of days. Vase life is 7 to 10 days.

Wit and Wisdom
  • The word “chrysanthemum” comes from the Greek words chrys, meaning “golden,” and anthemion, meaning “flower.” Its original color was golden, though mums now come in many colors.
  • Mums are considered an emblem of youth in Chinese and Japenese culture. The Chinese also believe that it prevents gray hair.
  • It’s said that a single petal placed in the bottom of a glass of wine enhances longevity.
  • In the language of flowers a red mum means “I love you” and a white mum means innocence, purity, and pure love.
  • The mum is November’s birth flower!
Pests/Diseases

Mums are susceptible to aphids, mites, and powdery mildew.

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