by Jennifer Poindexter
Do you purchase store bought mums each autumn? Do you have grand plans of ensuring these mums survive, so you won’t have to keep buying more each year?
I think many people do this only to be disappointed when their mums die over the winter. My mother is one of these people.
If you fall into this category, take a deep breath, and read through this article. I’ll be sharing why some mums simply don’t make it, how you can overwinter mums in the ground, and how you can overwinter mums in a container.
When you’re ready to stop buying mums year after year, here’s what you should know.
Will All Chrysanthemums Overwinter?
Mums, officially known as chrysanthemums, are gorgeous late summer and autumn bloomers. They’re beautiful when placed next to any pumpkin, scarecrow, or bale of hay.
Yet, they also shine beautifully in perennial gardens. It’s no wonder people flock to the local nurseries to buy them each year.
When you purchase mums from the store are they all created equally? Will all mums come back year after year?
In short, the answer is no. You must be careful of what type of mums you purchase. There are two different varieties.
One variety of chrysanthemum is called a floral mum. These are annual mums because they have such dainty root systems, they can’t handle the dip in temperatures over winter.
There are also garden mums. These are true perennial mums which are hardy in planting zones five through nine.
How do you know the difference between the two types? First, check the labels. Sometimes the sticker on the pot will specifically state if the mum is floral or garden.
If not, you can look at the pot and tell. When the mum is planted in a shallow container or planter and has small blooms, this is a floral mum. They don’t need deep containers because they have small, shallow roots.
Yet, if the mum is larger, in a larger container, with larger blooms, it’s safe to assume this is a garden mum. These are your perennial mums, so they may come with a higher price tag at the time of purchase.
Now that we have this significant detail under our belts, let’s begin discussing how to keep perennial garden mums alive over the winter.
How to Overwinter Mums in the Ground
The first thing you should do with any store-bought mum, when you get it home, is repot it. This is important to ensure the plant isn’t root bound and that it’s being provided adequate growing conditions.
Mums should be provided with well-draining soil no matter where they’re planted. They also like indirect sunlight. Ensure these two things are present wherever you use the mum for fall décor.
You may choose to leave your store-bought mum in a container while it’s decorating a certain area. However, you might choose to go ahead and plant it in the ground.
Either option is fine as long as you provide what the plant needs. If you choose to leave the mum in a container, ensure you plant it in the ground approximately one month before your first frost if you want to overwinter the mum in the ground.
This will give the plant enough time to establish its root system. When planting the mum in the ground, it must (again) be provided well-draining soil.
If not, the water will stand around the plant. As the temperatures drop, it will freeze around the roots of the plant and kill it.
It’s also a good idea to plant the mum where it will have some protection from high winter winds. This could be near your home, a shed, or near larger plants.
As frost moves in, it will cause the plant’s foliage to become discolored. Let it happen. After the foliage has died back naturally, it’s now time for you to do a little more trimming of the plant.
The mum should be pruned back to where there’s only two to three inches of the stem sticking out of the ground.
This is where the new growth of the plant will emerge next year. If you don’t leave enough stem, there won’t be much new growth the following year.
You’ll be done caring for the mum for a while. Wait patiently until the ground freezes. Once it’s frozen, it’ll be time to add a blanket of mulch over the plant.
The idea is for the mulch to keep the ground frozen all winter long, even when the temperatures fluctuate. If not, the ground around the mums will thaw and refreeze multiple times which actually does more harm to the plants than most other things.
Once the weather warms in the spring, you can remove the mulch and practice proper care for this perennial flower until it blooms again in late summer or early fall.
Now that you know how to overwinter an inground mum, it’s time to learn how to overwinter a potted mum.
How to Overwinter Mums in a Container
Overwintering mums in a container is a different process than what we’ve previously discussed. Where inground mums can handle frost, potted mums can’t.
Unfortunately, in a pot, mums don’t have enough soil to insulate their root systems. Therefore, it’s easy for them to freeze.
When the cold fall nights start to occur, bring your mums indoors overnight to protect them. As the colder temperatures become a permanent fixture (around 32-degrees Fahrenheit) you’ll know it’s time to start the overwintering process.
You might assume when the temperatures get cold, you should plant the mum in the ground. This would be one of the worst things you could do. If you don’t plant chrysanthemums in the ground at least a month prior to cold temperatures, you’ll kill the plant.
It won’t have enough time to form an established root system before it must battle the cold elements. Instead, leave it in the container and bring it indoors for its first winter.
When you bring the plant inside, prune it heavily. There should only be approximately two inches of stem standing above the soil level.
Once this is done, choose a dark location with milder temperatures to store the plant all winter. This could be a dark closet, a basement, or even a heated outbuilding.
The darkness and milder temperatures will encourage the plant to go dormant. This is your goal when overwintering mums in a container. However, be mindful that wherever you choose to store the plant that the temperatures are cooler but never to the point the plant will freeze.
While the plants are resting inside your home you must care for it occasionally. It’s wise to water the mum once or twice per month.
When in doubt, use your finger to test the soil. If it’s dry to your second knuckle, it’s time to apply more water to the plant.
As spring comes around again, it’ll be time for the plant to wake-up. One week before the final frost, you should start hardening the mum off by placing it outside for a few hours at a time each day. This will help the plant acclimate to the outdoors again.
Once all threat of frost is over, decide if you’d like to keep the mum in a container or transplant it into a perennial garden bed.
If you wish to place the mum in a perennial garden plot, ensure it’s planted in well-draining soil, and amend the soil prior to planting. The mum will be in need of food after a long winter.
Yet, if you’d prefer to keep the mum potted, you must transfer it to a new container with fresh soil. Again, this will give the plant room to stretch and will also provide nutrients.
Whichever planting method you choose, this is also an appropriate time to divide larger mums. If you have a mum that’s huge, use a garden spade to divide the plant all the way down the center and through the root system.
Transplant the two new plants either in new containers or in a perennial garden plot. This is what you must know to overwinter a potted mum.
If you choose to keep your mum in a container, you must continue the same overwintering process each year.
Also, as the plants begin to bloom in later summer, be sure to prune the blooms away. This will prolong the plant’s bloom cycle, so you can enjoy them in the fall.
Hopefully this information will help you to find success in keeping your store bought mums alive year after year.
I think where most people struggle with keeping mums alive is either they purchase the wrong type of mum, or they don’t know the proper times for mulching an inground mum or how to keep a container mum alive.
This information should not only help you find success in new gardening techniques, but it should also save you money in the long run as well.
Enjoy growing your mums, and we hope your home is gorgeous and full of color thanks to these beautiful plants.