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Are Fall Mums Perennial?

Are Fall Mums Perennial?

As I prepared to give my annual fall talk on perennial garden maintenance, a customer snagged me with the following question: “All those beautiful mums outside,” she said, waving toward the side of the store, “are they perennial? Will these fall flowers come back next year?”

My answer was this: “Yes, depending on how you care for them.”

The entrance to the garden center is filled with beautiful fall color.

The entrance to Hyannis Country Garden is filled with beautiful chrysanthemum, kale, and other fall plants, not to mention many decorative pumpkins.

The used to be in the genus Chrysanthemum but these lovely plants have been reclassified as Dendranthema x grandiflora. No matter what the current botanical name, these are commonly called hardy mums or just chrysanthemums.

My customer isn’t alone in wondering if they are perennial, however. The term “hardy” for these plants indicates that they will last through several light frosts in the fall…it doesn’t refer to their ability to return next year. Here on Cape Cod, however, these chrysanthemums will live through the winter and return next spring if you pay attention to them this autumn. Here are the keys to successfully helping mums to come back:

* Be sure to water these well once a week, even after they finish flowering. Remember that they have a root system the size of the pot, and because the roots are tight and congested they will dry out quickly. Most people tend to forget watering once the flowers fade. If you want your plant to return, water deeply once a week well into December.

* Don’t cut the spent flowers and foliage down in the fall. Even when the flowers have turned brown and the leaves have wilted, leave the stalks in place until spring. Sometime in March or April you can cut them back and at that point you’ll see the new foliage emerging around the old stems.

* Be sure that the plants were planted in well-drained but organically amended soil. If you didn’t improve the soil before planting, spreading a 1″ layer of organic matter (at the store, we like Bumper Crop and Quoddy Blend Lobster Compost) around the plants, spreading it out at least 12″ beyond each plant. This will improve the soil from the top down.

* Once your mums come up next spring, mark on your calendar to shear the top 2 or 3 inches off of the tops of the plants in mid-May. This will help the plant be full and bushy next fall.

There are so many colors of mums that it's hard to choose!

There are so many colors of mums that it’s hard to choose! They will be hardy on Cape Cod if you water well into December and amend the soil around the plants.

The growers who raise these mums shear them (or pinch off the ends) as they develop to help them to be this full. You can do the same thing in mid to late May.

Wondering how to grow mums on Cape Cod? The growers who raise these mums shear them (or pinch off the ends) as they develop to help them to be this full. You can do the same thing in mid to late May.

3 Comments

  1. Judy on October 27, 2016 at 9:23 pm

    PERENNIALS: I just received some perennials but am unable to plant them in the ground this fall, therefore have put them into pots with commercial-compost amended soil.

    My question is: How/where can I best over-winter these plants including: Siberian iris, bearded iris, lily, digitalis? When frost occurs can they be over-wintered in an unheated garage, or outside somewhere?

    Any advice your can provide would be most appreciated.

    • CLFornari on October 28, 2016 at 10:22 am

      Judy,
      Be sure these plants are in large pots – the more the roots are surrounded with soil the better protected they are. The best thing would be to pull against the house in a protected location and group together. They could also be put in an unheated garage but don’t move them in until well into December. If they are in a shed or garage check them once every two or three weeks and if the soil is drying water them well. Pull them outside in March to allow them to break dormancy normally and watch them in Feb to make sure they aren’t trying to sprout then…if they are you’ll need to put them out earlier to slow them down.

  2. Diane on October 18, 2018 at 1:00 pm

    Thanks to both Judy for asking and CL for the helpful answer! I have the same happy problem and was just wondering what to do. Perfect timing!

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