6 Mistakes You're Making With Your Mums—and How to Fix Them (2024)

Few flowers evoke the spirit of fall like chrysanthemums. When in full bloom, these perennials are filled with bright yellows, oranges, and reds that mirror the beauty of autumn foliage. And unlike some florals that can't survive the changing outdoor conditions, mums are an exception.

But if cared for incorrectly, their chances of survival during the cooler weather are slim, says Joyce Mast, Bloomscape's Plant Mom. "Garden mums, as a general rule, are extremely hardy and relatively trouble free," she says. "However, too much water can create mold and fungal issues on their leaves and stems, especially during the colder, darker, and wetter months of the year."

Along with issues stemming from overwatering your mums, not spraying your plants with a natural pesticide can cause major problems, too. Mast says chrysanthemums are known to attract sap-sucking insects, such as spider mites and aphids, which can lead to an infestation that will wreak havoc on your plants. "I suggest using neem oil to prevent and manage insect infestations on your mums," she says. "Just make sure to follow the dosage instructions closely." Curious what other mistakes you might be making with your mums? We tapped Mast to share more insight.

Sun Access

If your mums aren't receiving at least four hours of direct sunlight every day, Mast says their blooms will suffer. "Placing a mum in full sun, or as much sun as possible for approximately four to six hours a day is the best way to ensure your mums continue to bloom," says Mast. "The more natural sunlight they receive, the better their growth, bloom, and hardiness."

Drainage

When mums are planted in a pot sans drainage holes, a major problem can result. "Root rot occurs when excess water can't drain from the container," Mast says. "I recommend using only pots with drainage, because if roots sit in standing water they will die." To ensure proper drainage in your garden bed, she recommends not planting your mums in soil that is overly dense or clay-like. "If the soil feels too hard, mix in potting soil to promote better drainage," she says.

Watering

While overwatering your mums can lead to mold issues and root rot, Mast says not watering them enough can create problems, too. "Make sure your mums do not dry out, as this will cause the foliage to drop and blooms to fall off," she says. "When watering your mums, make sure to water under the foliage and on top of the soil to ensure the soil stays moist."

Overcrowding

Since overcrowded mums are forced to compete with each other for essential soil nutrients, Mast says planting them too closely together can stunt their growth, resulting in weakened foliage and fewer blooms. "Always plant mums at least 18 inches apart in the garden bed so they have plenty of room to spread and won't suffer from nutrient deficiencies," she says.

Repotting

If you purchase a plant from a garden center or nursery, chances are they'll be root-bound, meaning the roots are taking over the bulk of the pot, when you bring it home. "Root bound mum plants lead to bigger root issues," says Mast. "Repot your plant in a container that's about 2 inches larger than the one it's currently in, so the roots can spread and grow outward."

Deadheading

Mast says removing the old leaves and spent blooms from your mums, a process known as deadheading, is a foolproof way to ensure your mums stay in prime condition after flowering. "Your mums' energy will go to producing new blooms instead of trying to keep old ones alive," she says. To deadhead a mum, simply pinch off or cut away any dead blooms or foliage to promote new blooms and to reveal a healthy set of growing leaves.