How to Care for Mums So They'll Thrive All Season
By Erin Lindholm
Identifiable by its shrub-like shape blanketed in flowers often in fiery orange, golden, or burgundy hues, no perennial is more symbolic of the fall season than chrysanthemums, also simply known as mums. With proper care, mums bloom continuously for around eight weeks between late September, October, and well into November, as long as they’re sheltered from early frosts.
Taking care of mums requires just a little know-how, as they are a fairly resilient, low-maintenance plant that thrives indoors or outdoors with the right amount of sunlight and water. This guide covers all of the basics of how to care for mums, including how to transplant mums, how to prune mums to keep the blooms coming, and how to winterize mums. With the right care, mums will liven up your front porch, front yard, window boxes, or even indoor living spaces until it’s time to pull out the holiday decor.
Photo via Joanna - Gingham Gardens
How to Choose Healthy Mums
When selecting a plant that will thrive for the full season, look for one that is full of closed buds, which is an indication that it hasn’t yet burst with blooms. Repotting a plant in this stage is easier on the plant than if it’s already fully flowering, and generally, the flowering period will last longer. Look out for and avoid plants that have yellowish-brown spots on leaves, which may be a sign of disease (which we’ll go into detail about below).
Mums come in a spectrum of colors and more than a dozen varieties, including pompon, cushion, spider, and anemone mums. All mums fall into one of two primary categories: florist mums (sometimes known as “cutting mums”) and hardy mums (also known as “garden mums”).
Florist mums are primarily decorative plants grown in greenhouses and do best as indoor plants or planted in decorative arrangements outdoors with the understanding that they will die off once temperatures dip. Florist mums are such an inexpensive and accessible plant that they’re mainly treated as a short-term annual and are re-bought and replanted each fall.
Hardy mums are much better suited to grow as perennials, weathering winter outdoors in climate zones 5-9 and returning with new growth in the spring. Even so, planting hardy mums outdoors in the fall doesn’t guarantee winter survival. Their roots need to be firmly established to survive the winter while dormant, especially in cooler climates. To give your hardy mums a better chance at survival as perennials, bring them indoors that first winter for care and then plant them in the spring.
How to Transplant Mums
All types of mums make great decorative and container plants; they also grow well in garden beds alone or in clusters with companion mums or other plants. Believe it or not, mums also keep well indoors! The key here is to repot your mums once you’re home from the nursery. After months of growing in a nursery, your mums have likely developed a compacted root ball that needs more room and nutrients than its current container allows. Skipping this crucial step truncates the plant’s flowering cycle and ultimately shortens its lifespan.
These planting tips apply to transplanting mums both in containers and in the ground outside:
Step 1: Prepare Planting Location
Prepare transplant location with fresh potting soil (if moving to a new container) or garden soil mix (if planting outdoors).
Step 2: Remove Mum from Container
Pull the mum plant from its nursery container by its base and gently break up the root ball by shaking soil loose and detangling roots lightly with your fingers.
Step 3: Bury Plant
For ground mums: Spread out the roots gently in the gardening soil; layer another one inch of soil on top of the roots and tamp down around the base of the mum. The plant should be buried about one inch deeper than it was in the original nursery pot.
For container mums: The new pot or container should be at least 1.5 times larger than the nursery container. Plant the mum in fresh potting soil around ½-inch deeper than it was in the original nursery pot and gently tamp the soil down around the base of the mum.
Step 4: Water Well
After transplanting, give mums a good soak of water, saturating the soil. Follow up with lighter watering every other day or whenever soil seems dry to the touch.
Photo via Iwi28121322
How to Care for Mums Outside
Now that you know how to replant your chrysanthemums outside, follow these care tips to keep your mums thriving through the season and beyond if they’re hardy.
Sunlight and Temperature
Mums love abundant sunlight and thrive in full-sun locations. Without enough sun, plants will be tall and leggy and produce fewer, smaller flowers. Just be mindful: Although mums love the sun, they don’t like the heat that many climates are still prone to well into September. So even though pots of mums start arriving at garden centers at the same time kids go back to school, hold off on purchasing your mums until you see cooler temperatures are on the horizon.
Although they’re privy to full-sun, that doesn’t mean that chrysanthemums don’t like nighttime. Actually, they love it—10-12 hours of darkness each night gives mums the opportunity to bud up and develop flowers. That’s why these plants thrive in the fall when days are shorter.
Mums grow best in well-draining, nutrient-rich soil, where their shallow root system has room to expand. Mums also do well in raised beds planted in a rich garden soil mix high in organic material, or composted soil. (Note that if you’re planting mums in the fall, no fertilizer is needed.)
Sun-loving mums need plenty of water. Right after planting, water thoroughly every other day (or when soil is dry to the touch.) Once they are more established, mums require about an inch of water per week, which can be broken into lighter watering cycles every other day, or when the soil feels dry. Water at the base of the plant, directly into the soil, rather than soaking the foliage—wet leaves can lead to fungal disease.
How to Water Deeply
Also called “pinching,” this simple technique prunes the plant of spent blooms and encourages your mums to continue developing flower buds. Once a flower is visibly past its peak and begins to wilt, remove the bloom from the plant by pinching it off with your fingers or snip it off with small shears.
This light maintenance helps the plant to put more energy into producing new flower buds and healthy blooms and ultimately keeps the plant blooming longer since you’re thinning the competition for water and nutrients.
Pests and Diseases
Mums are susceptible to a few insect pests, namely aphids and spider mites. (There’s even a pest aptly called the “chrysanthemum aphid.”) Forceful water sprays directed at the underside of leaves (or any visible indication of the pests) every few days helps alleviate aphids and mites. Natural predators, such as ladybugs, are also beneficial. An insecticidal soap spray may help at the early stages of infestation.
With that being said, overly-wet leaves also leave mums susceptible to various fungal diseases, which cause yellowish-brown leaf spots, rust-colored patches, ash-gray powdery mildew, or gray mold, and ultimately inhibit the plant’s healthy growth. The best treatment is prevention: Avoid watering the leaves, unless absolutely necessary to spray for pests. You can handpick and destroy infected leaves and, if it gets bad enough, use a fungicide to help treat the disease.
If you’re in climate zone 5 or above and choose to grow hardy mums outside, improve their chance of overwintering with these tips:
- After the first hard frost, feed plants with a high-phosphorus fertilizer, which stimulates root growth. Also, make sure the soil is consistently moist.
- Layer a base of up to four inches of mulch (such as straw or shredded hardwood) around the base of the plants.
- Leave all branches intact—even though this growth will die over winter, it helps insulate the plant and gives your mums a better chance of making it through until spring.
- Come early spring, look for new growth around the base of the plant. Once temperatures begin to warm, pull mulch away to encourage the growth of new shoots.
- Come April, prune old growth from last year and remove winter mulch. (Consider replacing with a hardwood or cypress mulch for the growing season.)
How to Care for Mums Indoors
Indoor mums require much of the same care as their outdoor counterparts: lots of bright indirect light, consistent watering (water when dry to the touch), and regular deadheading of wilted blooms and dead stems/leaves to encourage new growth.
Florist mums cared for indoors will stop blooming after three or four weeks. After this, their lifespan is over and—as long as they’ve lived a healthy life with no disease or pest issues—can be composted in your garden. Meanwhile, all you really need to focus on with young hardy mums is keeping them green and healthy to put in the ground once spring comes.
How have you cared for your mums this season? Tell us about it in the comments below!