Hardy mums (Chrysanthemum morifolium) are herbaceous perennial flowers from the Aster family, featuring the characteristic daisy-shaped flowers. C. morifolium varieties are categorically different than the so-called exhibition mums, which are complicated hybrids bred for show and for floral display rather than to be garden hardy.
Hardy mums, on the other hand, are highly valued in landscaping because they bloom primarily in the fall, helping you to achieve four-season interest in your landscape. They come in a wide array of colors as well as different flower forms and growth habits. While they are legitimate perennials in moderate climates, hardiness in northern regions is not guaranteed, so hardy mums are often treated as annuals, planted in early fall as potted nursery plants that are already in bloom. Used this way, they provide a pop of color and are then discarded once the cold weather starts to depreciate their foliage and blooms.
Hardy mums are fast-growing and will reach their full height within their first year, with the plant filling out a little more each subsequent year. The leaves and flowers of hardy mums are mildly toxic to humans as well as to dogs, cats, and horses.
|Common Name||Hardy mum, garden mum, florist's daisy|
|Botanical Name||Chrysanthemum morifolium|
|Plant Type||Herbaceous, perennial (sometimes grown as annuals)|
|Mature Size||1–3 feet tall, 1–2 feeet wide|
|Sun Exposure||Full sun|
|Soil Type||Rich, moist, well-drained|
|Soil pH||Slightly acidic to neutral (6.2 to 7.0)|
|Bloom Time||Late summer to fall|
|Flower Colors||Gold, yellow, bronze, red, burgundy, pink, lavender, purple, cream, white, rust, white|
|Hardiness Zones||4–9 (USDA)|
|Native Area||Asia (China); modern types developed in Europe|
|Toxicity||Mildly toxic to people and animals|
Watch Now: Everything to Know About Growing the Hardy Mum Plant
Hardy Mum Care
If you want to grow them as true perennials, garden mums can be a bit fussy. Dozens of cultivars are bred for different regions and different growing conditions, so it's important to know the cultivar with which you are working. A University of Minnesota cultivar developed for far northern gardens, for example, might not perform well in a Tennessee garden.
Be sure to plant your mums in a site that’s protected from damaging strong winds. But provide good air circulation around the plants, which can help to reduce the risk of disease, such as fungal infections. For best perennial performance, garden mums require frequent pinching (in the United States pinch plants on or around Memorial Day and Fourth of July), weekly watering, and regular feeding. And in many regions, they will require some special care going into winter.
Garden mums become much easier to grow if you treat them as annuals, buying potted plants already in bloom to insert into the fall garden or in containers to replace faded summer flowers. Once they finally fade after a killing frost, you can simply pull the plants from the garden and discard them.
Hardy mums prefer to grow in full sun, meaning at least six to eight hours of direct sunlight daily. However, in the warmer parts of their growing zones, they can benefit from some afternoon shade. The flowers are photoperiodic, meaning they bloom in response to the shorter days and longer nights experienced (in the northern hemisphere) in the late summer and fall. Therefore, don't plant them near street lights or night lights; artificial lighting can wreak havoc with their flowering cycle.
These plants grow best in organically rich soil with a slightly acidic to neutral soil pH. Sharp drainage is a must, as soil that remains wet for too long can rot their roots.
Mums like consistent moisture but do not tolerate soggy soil. Water whenever the soil dries out about an inch or two down. In warmer weather and once the plant is large and in bloom, more frequent waterings will likely be necessary. About one inch of water per week is considered a minimum.
Temperature and Humidity
As their common name suggests, hardy mums are hardy to both cold and heat, but the degree of hardiness depends somewhat on the variety you choose, as many have been developed for the conditions of specific regions. Generally speaking, most garden mums can readily handle temperatures up to 100 degrees Fahrenheit, though they’ll need sufficient water and some shade in those conditions. Most hardy mums will continue to bloom as temperatures dip down as low as 20 degrees Fahrenheit; the roots of most varieties can survive winter soil temps down to zero degrees Fahrenheit or even a bit lower.
But recent introductions make hardy mums a viable plant even for gardeners in USDA hardiness zone 4, where winter temps can dip down to as low as minus 30 degrees Fahrenheit. Even zone 3 gardeners might be able to grow some varieties successfully. If you live in such a climate, though, it's important to choose varieties bred for such harsh conditions. Similarly, zone 9 gardeners will want to buy varieties bred for warmer conditions.
A moderate humidity level is ideal for these plants. Excessive humidity can encourage fungal disease, such as leaf spots.
Mums are fairly heavy feeders. You can use a slow-release fertilizer in the spring, following label instructions. Or use a water-soluble fertilizer monthly through July. Any fertilization after July can trigger tender new growth that cold fall temperatures can damage.
Types of Hardy Mums
Thirteen different classifications of mums are recognized, each with particular characteristics and many named varieties. The most popular categories include:
- Anemone: This group features long, flat petals on blooms that reach a maximum size of around 4 inches. Varieties include the light purple 'Dorothy Mechen' and 'Adrienne Mechen', which have flowers with a pink center that fades to bright white tips. Other varieties include 'Samba', with rose-pink flowers; 'Rhumba', with coral red flowers; 'Harmony', with bright yellow blooms; 'Overture', with bright red flowers; and 'Ruby Mound' with semi-double bright ruby-red flowers.
- Pompon: These fluffy mums are also known as button mums. All varieties produce compact blooms in various colors. Some common varieties include 'Patriot', 'Garnet', 'Tinkerbell', and 'West Point'.
- Spoon: Named for its spoon-shaped petals, this type of mum grows petite flowers up to 4 inches in diameter. Popular varieties include 'Kimie', featuring yellow-gold petals, 'Matchsticks', which have yellow centers that end dramatically in bright red "spoons," and 'Yellow Quill'.
Historically, garden mums are regarded as hardy only to USDA zone 5, but there are recent introductions by Canadian and University of Minnesota horticulturalists have created many varieties hardy to zone 4, and some even to zone 3. If you live in a northern climate, consider one of these:
- My Favorite™ series, developed by the University of Minnesota, is hardy into zone 3b. Plants are up to four feet tall, with coral, pink, or yellow flowers.
- Morden series, developed in Canada, is said to be reliably hardy into zone 3. Named cultivars include 'Morden Canary', 'Morden Delight', 'Morden Fiesta', and 'Morden Garnet'.
Other cultivars zone 3 and 4 gardeners can consider include 'Peach Centerpiece', 'Rose Blush', 'Sesquicentennial Sun', and 'Betty Lou Maximum', all developed by the University of Minnesota.
Pruning and Pinching
Pinching hardy mums (removing the tips of new growth, thereby stimulating the plants to send out side shoots) requires more maintenance than any other aspect of caring for them. But the effort pays off, because pinching yields compact, bushy plants with profuse blooms.
Start pinching in the spring when the new growth has reached roughly six inches long. Every two to three weeks, pinch back half of any new growth when it reaches six inches. Stop pinching chrysanthemums around the beginning of summer, around fourth of July, or else bud formation won't occur soon enough to ensure flowering for fall.
Spent flowers should be deadheaded to prevent the plant from becoming unkempt and to stimulate continued budding.
Propagating Hardy Mums
Hardy mums can be propagated in many ways, but the easiest is by dividing the root clumps in early spring:
- In spring just as new growth is starting to appear, use a shovel to carefully dig up the entire plant, including the crown and the full root clump.
- Use a sharp knife to cut the clump into sections. Each section should include a healthy group of roots attached to a portion of the crown.
- Immediately replant the divisions into the desired locations. If planting in groups, space the pieces at least one foot apart.
Mums can also be propagated through stem cuttings:
- In late spring or early summer when the initial shoots are 6 to 12 inches long, use sharp pruners to cut off three- to four-inch stem tips.
- Pinch off the lower leaves, then dip the bottoms of the cuttings in rooting hormone.
- Plant the cuttings in a rooting medium, such as coarse sand or perlite.
- Keep the cutting moist until roots begin to develop—generally four to five weeks.
- When a good network of roots has developed and the cutting is showing new leaf growth, carefully transplant the cuttings into the garden or into pots filled with standard potting mix.
How to Grow Hardy Mums From Seed
Growing hardy mums from seed is no easy task because the seeds are extremely small and it can take as much as 16 weeks for germinated seeds to develop into mature flowering plants. Furthermore, collecting seeds from existing plants is an unreliable method of propagation, because mums cross-pollinate freely and the plants produced from collected seeds might not be similar to the parent plants.
But if you want propagate mums from seed, collect some of the dust-fine seeds from dried heads of spent flowers. A better choice is to buy packaged seeds from a supplier. It's best to start seeds indoors at least six weeks before the last expected frost date.
- Fill a seed tray with a fine seed-starting medium, and dampen it slightly.
- Carefully sprinkle seed over the tray by pinching seed between your finger and thumb and rubbing them together over the tray.
- Just barely cover the seed with seed-starter mix, lightly mist the surface with water, and tamp the soil lightly to ensure seeds are in contact with the mix.
- Place the tray in a very bright, warm (70 degrees Fahrenheit) location, and keep the soil lightly moist. In 10 to 15 days, germination should occur.
- Thin out the seedlings as they grow, but don't attempt to transplant them into individual containers or into the garden until they are at least three to four inches tall.
Potting and Repotting
Garden mums adapt well to container growing in any well-draining pot filled with ordinary peat-based potting mix. If you live in a climate where garden mums are hardy, you might be able to overwinter the potted plant by moving it to a cold frame or other sheltered location. Otherwise, potted mums can be grown as annuals and discarded at the end of the season.
If you are growing potted garden mums as perennials, they will need to be repotted when the plant becomes root-bound, generally every two or three years. Potted mums do not adapt well to being moved indoors to grow as houseplants for the winter. They require some winter chill each year, so it's best to move your potted mums into a sheltered outdoor location, such as a cold frame or porch, for the coldest winter months.
In warmer climates (USDA hardiness zones 7 to 9), cut the plants back to about six inches after the fall-flowering period has ended. In colder climates (zones 4 to 6), it's best to leave the top growth in place and also apply a thick layer of dry mulch (straw, evergreen branches) over the plant to protect the crown over winter. In spring, cut off the dead stems to just above ground level.
Gardeners in cooler climates sometimes have good results overwintering garden mums by digging up and transplanting them into cold frames for the winter then moving back into their garden locations in the spring.
Garden mums are notoriously fickle, so don't be surprised if your efforts at overwintering are not always successful. Experienced gardeners learn to resign themselves to occasionally losing plants to winter cold.
Common Pests & Plant Diseases
Chrysanthemums have a natural resistance to many insects. In fact, an entire class of natural pesticides incorporates pyrethrin, which is derived from chrysanthemum flowers. But garden mums are still occasionally the target of small insects, such as aphids, thrips, spider mites, and leaf miner. If leaves show deformity, or if you notice fine webbing or trails on leaves, then using an organic pesticide such as neem oil is a good idea.
Garden mums can be susceptible to a variety of diseases, including botrytis (a gray mold disease that causes flowers to shrivel), aster yellows (a viral disease that causes yellowing foliage), and several other fungal diseases such as powdery mildew, verticillium wilt, and leaf spots. It can be worthwhile to use a spray fungicide to treat fungal diseases, but often the best approach is to remove affected plant parts—or even entire plants if the disease is widespread. Avoiding overhead watering can help prevent soil-borne diseases from spreading. Fungus only spreads on wet leaves, not dry leaves.
How to Get Hardy Mums to Bloom
Hardy mums will usually provide robust blooms if their basic cultural needs are met: plenty of sun and water, and early pinching back of the stem tips to create bushy rather than leggy plants. Lack of flowering is often traced to deficits in sunlight or water.
Unlike many flowering plants that don't like extra feeding, hardy mums often do respond to extra fertilizer and will produce more and larger flowers.
Common Problems With Hardy Mums
Garden mums are usually easy to grow provided they are given the right conditions, but they are relatively high-maintenance, so don't be surprised if some problems do arise. This is not a plant-it-and-leave-it specimen.
Yellowing leaves on garden mums is very often a sign of a viral or serious fungal disease. The best solution is to cut away all affected plant parts—or even remove and destroy the entire plant before the problem can spread.
Leggy, Droopy Plants
If mums are not severely pinched back as they first begin to grow in the spring, the plants can easily develop long, leggy stems that collapse under their own weight. For best results, hardy mums should be pruned or pinched back severely at least twice in spring and early-summer before the late summer and fall blooming season gets underway. Pinching back the plants will keep the plants from getting too tall and leggy.
Remember, too, that garden mums need a lot of sun, and if they are planted in shady conditions, the natural tendency will be for the stems to stretch in an effort to reach for more sunlight.
Plants Break Off at the Soil Line
It can be tricky to get the watering routine right with these plants. They need regular, reliable watering, but too much water, especially in soil that is too dense or has too much clay, can cause root rot that will soften the stems and cause the plants to break off. Make sure to adjust your watering routine based on how much natural rainfall is occurring. More than one inch per week might put your plants at risk of root rot.
Can I plant a gifted flowering mum plant in the garden?
Maybe. If the plant you received is a hardy garden mum, then it can probably be transplanted into the garden and grown on as a perennial, provided the variety is rated for hardiness in your climate. But if you received an exhibition-type chrysanthemum plant, it's unlikely it will survive and become a perennial in your garden. Such plants are often forced into early bloom under controlled lighting conditions, and they don't respond well to being transplanted into the garden. It's best to simply enjoy a gifted mum plant while it's in bloom, then discard it.
How long does a garden mum plant live?
Garden mums are relatively short-lived perennials, rarely living more than four or five years, at most. At this point, the root clumps become overgrown and woody, and the plant dies. However, division of the roots every two or three years allows you to effectively keep the plant (or at least identical copies) growing for as long as you want.
How should I use hardy mums in a landscape?
These fall-blooming plants are often planted as annuals in the late summer and fall to replace summer-blooming annual plants that have faded. In this use, they also make excellent potted plants for decks and patios. Used as perennials, they are useful as permanent bedding plants to keep the color display alive well into late fall.
“Chrysanthemum x Morifolium.” Ncsu.Edu.
“Chrysanthemum Classifications.” Mums.Org, https://www.mums.org/chrysanthemum-classes/
Kluepfel, Marjan, et al. “Chrysanthemum Diseases & Insect Pests.” Home & Garden Information Center | Clemson University, South Carolina, 30 July 2021, https://hgic.clemson.edu/factsheet/chrysanthemum-diseases-insect-pests/