Are the Mums We Grow Actually Perennials?

Here’s one of the most confusing questions in fall gardening: “Are these hardy mums?” With most of the garden mums we grow, the answer is yes — technically, they’re perennials. So why do so many mums planted in September never come back?

Because whether a plant can survive an Indiana winter and whether the particular plant you bought in fall will are two very different questions.

We grow modern garden mum genetics from major breeders including Yoder and Ball, with varieties such as Cosmic and Danielle. These plants have been selected for the traits that make an exceptional fall mum:

• ✓ Heavy flowering
• ✓ Uniform color
• ✓ Dense, rounded habits
• ✓ Predictable flowering windows
• ✓ Outstanding container performance

They’re perennial chrysanthemums. But when you buy one covered in flowers in September or October, that plant has spent its energy doing exactly what it was bred and grown to do: bloom. It hasn’t spent the summer building a massive root system in your garden. And that’s where the trouble starts.

Purdue recommends late spring — typically around mid-May — as the best planting time for chrysanthemums in Indiana, and specifically notes that fall planting has not proven very satisfactory across much of the state. That’s important. A mum purchased in September isn’t necessarily dying because it isn’t hardy. It may simply have run out of time.

A perennial survives winter primarily underground. To do that, it needs a healthy, established root system before the soil freezes — and the later you plant, the less time it has.

There are chrysanthemums selected primarily for garden hardiness and perennial landscape performance, and those can be excellent if returning year after year is your main goal. Modern garden mums, by contrast, are bred heavily around fall performance — habit, flower coverage, color, and precisely timed blooming. They’re still perennial plants. But I’d buy a beautiful fall garden mum because you love how it looks this fall, and treat its return next spring as a bonus.

If overwintering is the goal, plant it as early as possible in a sunny, exceptionally well-drained spot, keep it watered while establishing, and give the roots every chance to develop before winter. Purdue emphasizes that well-drained soil matters especially when mums are meant to overwinter.

“Perennial” describes what a plant is capable of. It isn’t a guarantee. And with fall-planted mums in Indiana, when you plant can be every bit as important as what you plant.

Reference: Purdue University Extension · Schlegel Greenhouse production notes