Every year in the fall, I suffer a bout of mum madness when garden centers and big boxes brim with cheery chrysanthemums. They produce lovely fall colors, but is fall really the best time to plant them? (The answer is no.) Here’s how to keep your mums alive through winter!
When to Really Plant Mums
Then I slap myself on the forehead, take a deep breath and cry “You should have planted these in May!”
People start pointing at me and make avoid-the-crazy-woman sounds to their children and spouses. I slink off to the refuge of my car or the plumbing department to avoid further embarrassment.
Why Mums Don’t Often Last Through Winter
Chrysanthemums are a hardy perennial plant best planted in the spring, but those that are sold in garden centers in the autumn are really being treated as annuals. They are already in full bloom with beautiful autumn jewel-hued colors to decorate your house, along with autumn wreaths and gourds. Once a flower is in full bloom, it’s actually past its peak and already declining. (Be sure to buy mums with lots of unopened buds so that they last longer into the fall season.)
If these plants are put in the ground from mid-September on, most won’t make it through the winter in areas where temperatures dip into the single digits during the winter months. The reason being that mums planted late in the season are near or at the flowering stage, and they don’t put energy into growing roots to sustain plants through the winter. All the energy is put into blooming. That’s why mums are best planted in the spring!
Gardeners in northern states where temperatures regularly dip below zero can lose even spring-planted hardy mums to winter. You can changes the odds in your favor by leaving the dead foliage on mums and asters instead of shearing them down for neatness. An Iowa State University study found that unpruned plants survive at much lower temperatures than those that were pruned. Be sure to add 4 to 6 inches of mulch after the ground has frozen for even more protection.
Potted mums from the florist or grocery store, as well as exotic types (like huge Football chrysanthemums, delicate Spiders, and Spoons), don’t survive cold winters either and are generally not good choices for landscapes. They are not bred to be hardy; it’s their form, color, and size that are prized. Think of them as disposable holiday decor, along with the pumpkins you buy for Halloween or otherwise.
How to Overwinter a Mum
Want to give your mum her best shot at overwintering and returning next year? Follow these tips:
- For your fall mums to have the best chance at survival in cold areas, overwinter them in the basement or a dark, cold closet.
- Pot up plants after the first fall frost if they are in the ground; include as much root system as possible.
- Leave the foliage on the plants until spring.
- Water well and place in a protected area where it is totally dark and 32º to 50ºF.
- The plants will hibernate for the winter if you keep their roots damp. Check pots weekly.
- In the spring, acclimate plants to light gradually and set them out in the garden after the last killing frost.
With a bit of forethought and care, you can keep your mums blooming year after year!
Want to read more about mums? Check out our Growing Guide for Chrysanthemums for growing and care tips.