Chrysanthemums, commonly known as mums, are a favored flower by many gardeners thanks to their brightly colored and ornamental nature. Mums can range in hardiness depending on species, and many gardeners look for ways to keep these flowers alive through frosts and winter.
Mums are generally considered either tender or hardy perennials, the latter being able to withstand winter to an extent. Frosts will likely cause damage to mums if the plants are not covered or protected in some way.
The reality is that there are several factors that go into whether or not your mums can withstand the frosts and weather of winter. In this article, we will cover the type of mums best equipped to handle frost, the impact of being planted in the ground versus potted, and the best time of year to plant mums.
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Hardy Mums Can Survive Frosts
When discussing plants, it is important to know if the plant is either annual or perennial. Annual plants are those that grow for one season and then die, while perennial plants are those that have the ability to go dormant in the winter and regrow in the spring. Chrysanthemums actually fall into both categories.
According to an article in Gardening Know How written by a certified urban agriculturist:
“There are several species of chrysanthemum, with some being hardier than others. The perennial types are often called hardy mums. Whether your chrysanthemum will come back after winter depends upon which species you have.”
Hardy mums are also known as garden mums, and they are considered the perennial type of mum, meaning they should be able to withstand some levels of frost and winter. However, location can be an important factor into whether or not the plants survive.
Understanding how different climates affect plants is crucial for knowing where different species can grow. For gardeners in the United States, the U.S. Department of Agriculture (USDA) provides a plant hardiness map available as a resource that divides the nation into zones according to overall climate and temperature.
The zones are generally defined as being regions that have a 10 degrees Fahrenheit difference in winter averages, with the first zone being the coldest zone and the number assigned to each zone moving up in temperature.
Mums are categorized as being able to survive in zones 5 – 9, according to HGTV. These zones encompass the majority of the states in the U.S., generally only excluding the very far north states close to the Canadian border. Even parts of Alaska are included within zones 5 – 9.
Ground-Planted vs. Potted Mums
The way in which mums are planted can also have a major effect on how well they withstand the frost and other winter conditions. Due to hardy mums being the perennial type, we will be focusing mainly on them. Other types of mums can also be planted in similar ways to hardy mums, they just may die regardless after one season due to being annuals.
There are several ways in which mums can be planted, and they can be grown both indoors and outdoors. However, oftentimes mums that are potted tend to not live as long as ground-planted mums in an outdoor garden. This can be for several reasons, from not developing strong enough root systems to being treated as annuals and discarded at the end of season.
According to one article on Hunker:
“Potted mums sold as gifts — like those often seen at a florist — are exotic and not hardy enough to survive winter temperatures, even in USDA zone 9. These mums, which feature unusually shaped or very large flowers, are usually treated as annuals by home gardeners.”
Nonetheless, with the right care, potted moms can survive frosts as successfully as ground-planted mums. Proper care is essential for ensuring your mums last through to the next season and come back strong in the spring.
Protecting Outdoor Mums from Frost
Protecting your mums from the frost is important not only for the survival of the plant, but also because frosts can happen early into the autumn season in some areas. This is problematic, as mums bloom during the late summer and throughout the fall, and an untimely frost can cut this blooming short.
There are several steps to protecting your mums from the first frost of the season and the later winter conditions to come. One of the most important first steps is to be aware of upcoming weather and freezes so that you can plan accordingly and not be taken by surprise in the morning from an overnight frost.
Additionally, it is important to be considerate of day-time temperatures as well. Even after the morning frost, if the outside temperature is still below freezing, your mums will likely suffer if not properly protected.
For ground-planted mums, there is not as much you can do to prevent frosting as there is with potted mums. However, you can certainly drape a cover (such as a tarp or blanket) over top in order to shield the plants. A tent or foldable greenhouse placed over top of the flowers may also be useful in smaller gardens. Extra mulch can also be helpful in protecting the plant’s roots during the cold.
For potted mums that are kept outside, the best bet is to move them under some sort of cover such as under the shelter of a porch deck or awning, into a garage, or into a collapsible greenhouse. Ensuring your potted plants are well-drained and being provided with enough nutrients from their soil is also essential.
When moving potted plants into a shaded area, it is also key to be mindful of how much sunlight they get throughout the day, as mums require at least 6 hours of sunlight per day. For plants that have been moved indoors, this light can be supplemented or replaced by led grow lights if the outdoor environment remains too frigid for the mums.
Best Time of Year to Plant Mums
The best time of year to plant your mums can greatly depend on whether you have opted for ground planting or potting. Many growers new to mums or simply those who grow them as annuals rather than perennials may plant in the mid to late summer, as mums bloom throughout the fall.
However, springtime is generally considered the best time of year to plant mums in the ground, as this will give them the longest opportunity to develop and grow strong root systems that can last through the winter.
With potted mums, planting in the spring can be equally beneficial, though it depends on how much time you plan to keep them indoors. The more time they spend in warmer air indoors, the less vulnerable your potted mums will be to cold conditions and frost.
To Prune or Not to Prune
Pruning is a normal process for most plants that involves cutting down and removing certain parts of a plant to help them grow. When pruning mums in the winter, it is important not to cut the stems all the way to the ground, as the dead foliage and withered parts may actually help to provide insulation for the plant during winter.
Instead, simply trim the stem a few inches from the ground, so there is still a decent amount of stem for the plant to regrow from next year.
Frost does not have to be a death sentence for you mums. In fact, hardy mums are more than capable of surviving through the winter and coming back in the spring thanks to their status as perennials. Nonetheless, even though they are dormant your mums will require some winter care to keep them strong and ready to return come spring.