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

Chrysanthemums

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Savina Nataliia/Shutterstock
Botanical Name
Chrysanthemum x morifolium, C. rubellum
Plant Type
Sun Exposure
Soil pH
Bloom Time
Flower Color
Hardiness Zone
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How to Care for Mums

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Chrysanthemums, aka “mums,” are the quintessential autumn flower. How do you care for your mums so that they come back year after year? How do you keep them blooming and what do you do to overwinter mums? See our complete guide on growing mums. 

Chrysanthemum x morifolium is the Queen of the Fall Flowers, celebrating the season in jewel colors: yellow, lavender, pink, purple, red, bronze, orange, and white. Each bloom consists of tiny flowers called florets. Bloom forms range in size from pincushion petite to giant spiders, and there are hundreds from which to choose.

Mums generally grow to a width and height of 3 feet tall if they are pinched regularly during the growing season. Bloom time is determined by day length (12 hours or less!), and buds start forming then. Mums spread quickly if properly planted and spaced.

Are Mums Perennial or Annual?

Mums are hardy perennials best planted in early spring. However, those pretty mums sold in garden centers as fall decorations as often best treated as annuals; do not try to overwinter them, as they weren’t bred to be hardy.

Do Mums Come Back Every Year?

Yes, if you plant a cold-hardy perennial that’s marked to withstand low temperatures, it will come back every year. Early spring is the best time to order and plant mums to give them time to grow strong roots, become well-established before winter, and grow into a more robust, full plant. 

Southerners can enjoy the colorful displays of blooming mums twice yearly because the equal days and nights of temperature weather that cause mums to bloom happen in both the spring and the fall. Northerners must be satisfied with one show in autumn. 

Pink Mums growing outdoors in Ohio.
Mums growing outdoors in Ohio. 
Credit: Catherine Boeckmann
Planting

Select a planting site in full sun, away from trees and big shrubs. Mums require rich, well-draining soil. They do not like standing water and will quickly rot if left too wet. Prepare by adding aged manure or compost to the soil (mums are heavy feeders).

Container Tip: Many folks will set their potted mums on or near their porches. Plants that receive light at night from security lights or street lights will be slow to bud! If you’re wondering why your mum isn’t blooming, it’s often due to this reason (as well as lack of sun or water).

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

  • Set mums 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 that it was grown at in the pot. Water can gather around the base and rot the stems if planted too low. 

a cluster of orange mums

  • Water and keep it evenly moist. 
  • If you are growing mums in pots, they will be dry in no time, and you must keep them moist; when you water, it should drain out the bottom. (If you buy mums in wrapped containers, make sure they have drainage holes!)
Growing
  • Watering mums is vital to success; too little water slows or stops their growth! Keep mums moist. Soak the soil deeply when watering. Avoid watering the leaves. 
  • Mums are heavy feeders. A monthly application of a balanced fertilizer (10-10-10) is good practice.
  • Spread mulch around the mum to conserve soil moisture and to keep weeds out.
  • Pinch back stems to create a bushier plant: When new shoots are 3 to 4 inches tall, pinch off the top, leaving 2 to 3 leaves on the shoot. Continue pinching every 2 to 3 weeks until mid-July, when buds develop. On the West Coast, stop pinching in early July. In the South, stop in early August.
  • Stop fertilizing when flower buds emerge. 
  • 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 the 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 the fall. The dead growth insulates the roots. Cut off the dead stems and leaves when you see the first green shoots in spring.

pink mums planted outside in a garden with mulch

Overwintering Mums

USDA Hardiness Zones 5 and warmer, perennial chrysanthemums can be kept outdoors (in the ground) through the winter. But in extremely cold areas, 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.

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.

Dividing Mums

Every 2 to 3 years, divide  mum when new growth appears in the spring. Use a knife to 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 arrangements when they are nearly or fully open. Remove lower leaves that would be in the water. Leaves submerged in water will rot. Change the water in the vase every couple of days. Vase life is 7 to 10 days.

pink chrysanthemums

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Wit and Wisdom
  • The chrysanthemum was a culinary flowering herb in the 15th century B.C. China. It was a healing herb said to have the power of life, healing headaches and other maladies. The earliest illustrations show mums as small, yellow daisy-like flowers.
  • 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.
  • It’s said that a single petal placed in the bottom of a glass of wine enhances longevity.
  • The mum is November’s birth flower!
Pests/Diseases

Diseases: Aster yellows, Ascochyta ray, crown gall, leaf spot, powdery mildew, Pythium root, and stem; Rhizoctonia root and stem, Fusarium wilt, Verticillium root
Pests:  Mums are susceptible to aphids, foliar nematodes, and spider mites.

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