Growing Mums: How To Care For The Classic Fall Flower

At Gardening Know How we receive questions year round about how to care for mums. With some helpful tips from Amy Draiss, one of our gardening experts and a major mum fan, we’ll cover the details about how to take care of mums ranging from purchasing, planting and nurturing to propagating and overwintering.

All About Mums

As gardeners, we think about “mums,” (a simpler way to say “chrysanthemums,”) when summer days begin to cool and shorten. In most regions of the U.S. mum plants that appear on the market in early fall are produced for their beautiful flush of decorative autumn flowers. However, most of those store-bought “florist mums” have not had time to grow much of a root system and often tend to die in winter.

Though they do add rich color while they last and are beneficial for pollinators still seeking food in the fall. Planting “garden” mums in the ground in spring is a way to cultivate sturdier plants that will provide beauty and color year after year.

Garden mums, formerly called “hardy” mums, are hardiest in USDA zones 5-10. If you live in one of the warmer of these zones, you can treat them as perennials by planting seedlings in spring. This allows plenty of time for the plants to grow a strong system of roots before they bloom in the fall. In these warmer climates or in sheltered locations chrysanthemums can return and bloom year after year.

Here at Gardening Know How, Amy tells us, “The best bet is to plant hardy garden chrysanthemums in the spring. Planting early can ensure they get rooted before cold weather arrives, especially in zones 4-6. If you are in a warmer climate, it is also best to plant in the spring as this avoids the extreme heat of the summer months.”

Amy Draiss

As a former garden center manager with over 25 years of personal gardening experience, Amy knows her mums. She has worked with mum experts and sold thousands of these fall favorites during her time in retail. Plus, she lives down the road from an enormous mum festival that features nearly 20,000 plants each year!

Types of Mums

Chrysanthemums come in pretty colors, including red, coral, pink, lavender, bronze and white. There are several varieties of mums that differ in their shape, size and appearance.

Your local garden center or big box store may offer single, pom-pom, cushion, anemone, spider, spoon, quill and decorative varieties. When purchasing fall mums for decor, be sure to choose the ones with lots of small buds. Plants with tight flower buds will open gradually, making the bloom period last longer.

How to Care for Mums

If you love perennials and want your garden mums to continue to thrive when they’ve finished blooming, here are some tips on their basic care:

Light

A mum grown outside requires full sun exposure, which means 6 hours or more of unblocked sunlight. Be sure the plants aren’t exposed to nighttime outdoor lights, which could affect their ability to form flowers.

To learn more about how to find the perfect full sun location in your garden or yard, try mapping the sunlight making note of any shadows from trees, shrubs and buildings that might block the sun during certain daytime hours.

Water

Always water mums at their base. Getting the leaves wet can lead to fungus and other problems. Keep the soil moist but do not overwater. If the soil is dry at least an inch (2.5 cm) deep, the mum needs a drink. In many areas, rainfall is sufficient to keep them watered.

Temperature & Humidity

As mentioned earlier, in warmer temperatures hardy mum plants grown as cuttings can be planted in the garden in early spring and should rebloom each fall. In colder climates you may have to settle for enjoying the plant until the first heavy freeze, and plan to buy a new one next year.

Soil

Fertile soil that drains well is important for keeping your mum plants happy and healthy. They like moisture but do not appreciate soggy soil, so be sure your soil content has a bit of coarse sand or other qualities that make it drain well. Amy says, “Oftentimes it isn’t the cold that kills mums, but rather soil that remains wet and saturated over the winter. This is why choosing a spot with very well-drained soil is crucial.” Chrysanthemums thrive in soil that’s slightly acid with a pH level of 6.5.

Fertilizer & Mulch

Once your planted mums have settled in and begun to grow for a few weeks, they can be fed with garden fertilizer that’s high in nitrogen and potassium. This should be done during their vegetative phase, before they bud and after the last frost. A monthly feeding of mums until the plant is forming buds is sufficient.

When the plant goes dormant and is cut back, a heavy layer of mulch may save it for the following year as described in the overwintering section below. However, in early spring after the last frost it’s important to move mulch away from the plant.

Problems, Pests & Diseases

Growing mums is somewhat carefree, but they can have occasional problems. Always remove yellowing mum leaves and keep the area around the plant free of weeds. Insects found on mum plants are primarily mites, aphids, thrips and leaf miners. Viruses that have no cure can be transmitted by sucking insects. Signs of yellow ring spot, tomato mosaic virus, and chrysanthemum smut virus may signal that it’s time to destroy the plants.

Pruning Mums

If you’ve planted hardy mums and they sprout back up the next spring looking scraggly or leggy, remove the tip of the plant and pinch it back again during the summer. Taking the new center growth away will encourage the plant to produce more stems below, making it fuller and bushier. When summer starts to ebb, stop pinching them back so they’ll have a chance to develop blossoms.

When it comes to pruning mums, Amy feels “It’s best to remove any dead foliage in spring, and pinch the plant back after the first flush of new growth to promote a well-rounded and bushy plant.” Especially in cooler climates, she tells us it’s best to leave any and all foliage over the winter so the plant’s leaves can help to protect its crown. In fact, one of the largest mum breeders in the U.S. has proven through experiments that mums cut back in early spring, instead of fall, survive hard winters better.

Overwintering

Garden mums can be overwintered year after year. Be sure your mums are in a location where they won’t be damaged by wind. After a few hard frosts have visited your region, the foliage of your mums will die back. Cut the stems back, leaving 3-4 inches (7.6-10 cm) on the plant. These short stems will give new stems a place to sprout from in the spring.

Spread a heavy layer of straw or leaf mulch over the plant but, if you’re in a particularly cold region, wait on mulching until the ground has frozen; it’s better for the dormant plant if the ground stays consistently frozen rather than allowing it to thaw and freeze repeatedly over winter. Amy reminds us, “Many types of mulch including hardwood or pine, straw, evergreen branches or even fallen leaves can all help to insulate the plant over the winter months.”

Propagating Mums

Chrysanthemums can be propagated from seed or with cuttings, or existing plants can be divided.

Be aware that when seeds are harvested from your garden mums, they may not prove to be true to the parent plant, but it can turn out to be an interesting experiment.

By Seed

Start seeds indoors 6-8 weeks before the last frost, and transplant the seedlings when they’re 6-8 inches (15-20 cm) high. Mum seeds can also be direct-sown into the garden soil if you cover them with a light layer of mulch and keep them moist.

By Cutting

Take cuttings from a healthy plant using a sharp sterile knife. Remove a 2-3 inch (5-8 cm.) section at the end of the stem. Cut away all leaves on the bottom inch (2.5 cm) of the cutting and push them into a container of moist peat moss or perlite. Be sure the planting medium doesn’t become soggy. Your cutting will root in a couple weeks. Pinch off the top growth to keep the lateral stems developing.

By Division

Garden mums can get overcrowded after a few years. To divide a mum plant, dig up the entire root ball in the early spring after the last hard frost but just as the plant begins to break dormancy. With a garden knife or spade, separate the outer portions from the center, leaving each section with some of the root and at least a few shoots. Install these new “plants” in rich soil and water them in. This process can apply to containerized mums, as well.

Caring For Potted Mums

A containerized mum can be beautiful on a porch or deck, or even indoors. Living in a pot, the mum still needs full sun and moist soil and careful attention to watering. Wet feet will take it down quickly. If your potted mum attracts insects, use a horticultural spray or neem oil to keep it healthy and be sure to remove any diseased leaves and stems.

The signal for mums to begin flowering is when they sense cooling temperatures. If you’re growing one indoors, be sure your indoor night time temperatures stay below 70 degrees.

Store bought “florist” mums are often root-bound, so it may be a good idea to repot your mums right away. Follow the same rules as you would with garden mums, and be mindful that they’re subject to the same requirements. Amy says, “One of the best things you can do for your mum is to repot it.“

If you want to try overwintering a potted mum, cut it back after it has finished blooming, put some mulch over the top and place it in a cool, protected area like a basement or garage. It might come back next year, but mums sold in the fall often have a short lifetime.

Frequently Asked Questions