7 Common Mistakes You're Probably Making with Your Fall Mums

·4 min read

Gorgeous mums in shades of red, yellow, orange, purple, and white pop up everywhere in the fall. I like to use them for autumn displays on my porch, along with dried cornstalks, gourds, and pumpkins. After the flowers finally finish blooming, sometimes as late as November in my warm Southern climate, I often try to plant them in my garden because most mums are actually perennials that survive the winter. But by the following spring, my plants are usually reduced to clumps of dead stems. After checking in with a few mum-growing pros, I realized I was planting my mums too late. In fact, garden mums are fairly easy to grow, once you know the following common mistakes to avoid.

William N. Hopkins

1. Ignoring the Type of Mum

Amy Enfield, a horticulturist for Miracle-Gro, says garden mums should be planted outdoors by late summer or early fall, so the roots have time to form before the soil freezes. Also known as hardy or Belgian mums, garden mums are sold in garden centers and nurseries, and they're perennials in USDA Zones 5 to 9. But even when they're planted at the right time, they need a few other things, like excellent drainage. Enfield adds, "There's no guarantee they will survive the winter, particularly the further north you live in the U.S."

Related: When You Should Set Out Your Mums for the Longest-Lasting Fall Flowers

Florist mums, the kind sold in the houseplant section of your local grocery store, aren't meant to transplant at all, she explains. "Unlike garden mums, these are meant to grow inside as indoor potted plants and are not cold hardy."

2. Planting in Too Much Shade

Cynthia Drumgool, a potted plants and mums manager with Ball Horticultural, says garden mums need full sun or at least partial sun. One exception: in very hot climates, mums benefit from a little shade during the hottest part of the day. Otherwise, give them plenty of sun for plenty of blooms.

3. Over-fertilizing Your Plants

In spring, you can give your plants fertilizer with nitrogen when they're starting to grow leaves and branches. But don't fertilize once your mums form flower buds, says Enfield. In the fall, mums will benefit from a high-phosphorus fertilizer that promotes root development.

4. Forgetting to Water Mums

One of the biggest mistakes you can make with fall-planted mums, Enfield says, is failing to water them. "Days are cooler, the sun isn't as intense, so plants, even those in containers, don't dry out as quickly. However, plants will continue to require water until the ground freezes." While you may need to water daily in the summertime, after the weather cools down, water only when the top inch of soil feels dry to the touch. Do the same for potted indoor mums.

5. Cutting Plants Back Too Soon

Deadhead your garden mums in the fall, but leave the rest of the plant alone for as long as possible, Enfield advises. Mums use their leaves to turn sunlight into energy for forming roots. Wait until the following spring to do any additional pruning, or until the stems die back to the ground. Then, cut the stems down to about an inch or so above the ground before new growth appears.

6. Pinching Mums Too Late (or Not at All)

If you don't pinch the growing tips of your garden mums, they'll bloom, but you'll have plants with long stems and fewer flowers. "Pinching to remove flower buds helps encourage the plant to branch and become fuller," Enfield says. "Stop pinching in early July (no later than mid-July) and allow the buds to form and flowers."

7. Not Improving Drainage

Mums won't thrive in soil that drains poorly and stays too soggy. That's especially true in cold-winter areas, says Enfield. If you have heavy clay or compacted soil, mix in some good-quality garden soil or compost to loosen it and improve the drainage in your planting site.

Carson Downing

Finally, keep in mind that the fall mums sold in garden centers nowadays aren't the same kinds of plants sold 20 years ago, Enfield says. Although garden mums are considered hardy to Zone 5, breeders have developed fall mums with big mounds of showy flowers. This has resulted, she says, in plants that may not be as cold hardy as in the past. So, if your fall-planted mums don't come back like true perennials, just treat them like annuals. Replace them with beautiful, fresh plants when you're ready to do your fall decorating and enjoy their colorful blooms for a season.