Why Are My Mum Flowers Turning Brown?

Mums flowers, also known as “Chrysanthemum” is a popular flower genus that belongs to the Asteraceae family. The flowers are characterized by their multi-petaled look and vibrancy of color, as they come in shades of purple, yellow, white, orange, red, and more!

Beautiful yellow Chrysanthemum

One question that many beginner mum growers ask is “why are my mum flowers turning brown?”

There are plenty of reasons that can cause them to turn brown, wilt, and die. In fact, mum flowers can turn brown due to natural causes like going dormant in the Fall or inadequate growing conditions as well as infections and diseases.

If you want to know more about these reasons as well as what to do in each case to help, keep on reading this guide!

1. Going Dormant

The first and most common reason why mum flowers turn brown is simply because it’s a part of their natural course of life.

Chrysanthemum is a large genus that has up to 40 different species found in the wild. Some of these species are perennial while others are annual.

The perennial species of Chrysanthemums are known as “hardy mums” due to their high ability to adapt and endure various conditions.

However, like all living organisms, there will come a time when the flower will simply run its course and turn brown.

Some species of Chrysanthemum will bloom in early fall, displaying their beautiful colors all through September and October. With that said, mum flowers will typically go dormant in Winter.

During that time, the flower will turn brown, droop, and eventually, fall off. Luckily, it is only a matter of time before the flowers regrow and bloom again in the next Fall season. 

All you need to do is provide them with the necessary growing conditions and wait for them to come back again the following year.

2. Not Enough Light

Withered Chrysanthemum flowers in a pot on a gray background

If the mums flower is turning brown in months other than winter, it’s probably due to improper growing conditions that are necessary for the plant to thrive.

The first thing you need to check here is sunlight exposure. As a flower that is originally native to East Asia, they typically grow best when provided with bright sun exposure.

Ideally, the vibrancy of the colors of the Chrysanthemum petals is directly proportional to the amount of full sun they’re given. This is because bright light is necessary to synthesize their food as well as the pigments of their colors.

If the flower doesn’t get enough sunlight, it’ll go into “energy saving mode”, where it directs the little energy it gets to only making food and surviving, which turns the petal brown.

With that said, intense sun exposure in hot regions may not be ideal as well because it can scorch or dry the petals and leaves of the flower.

The solution here is to make sure that the flower gets at least 6 hours of daily sunlight exposure and only use partial shade if you live in an area where it gets very hot in the summer.

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3. Underwatering

Another important aspect that you need to keep in mind while caring for Chrysanthemum flowers is to make sure that they’re getting enough water.

Similar to light, water is also a necessary component for the photosynthesis process to occur. As such, when the plant doesn’t get the amount of water it needs, they end up turning brown.

To avoid underwatering your mum flowers, you’ll need to water the mature plant anywhere from 2 to 3 times every week, which is quite a lot when compared with other flower species.

The tricky part here is that too much water can also hurt your Chrysanthemums, as overwatering can suffocate the roots and cause problems like root rot.

A good rule of thumb here is to always test the soil’s moisture level before watering the plants. Ideally, if the topsoil is relatively dry, you should water the plant immediately.

On the other hand, if the soil is soggy or wet, you need to wait a couple of days and check it again.

4. Poorly Drained Soil

Speaking of soil, you also need to make sure that you plant your Chrysanthemums in the right soil to thrive.

For instance, you might be ready to water the plant according to the previously mentioned frequency, but you always find the soil too wet.

In that case, the soil has poor draining properties, which retains the water inside and puts the plant at risk of root rot, which ends up killing the plant permanently.

Always make sure that you use well draining soil for your plant, and you can make the soil well drained by digging organic matter into your soil. A sandy loam soil with good aeration would be excellent for such flowers.

Remember to also check the pH of the soil and make sure that it’s slightly acidic with a pH level between 6.5 to 7.0. You can use a pH Tester for that purpose.

5. Transferring to a New Environment

If you’ve recently bought a new batch of mums and you’ve transferred it to your soil while taking care of all the necessary conditions, the plant might turn brown, which is confusing to many beginner growers, but it’s really no problem at all.

This phenomenon is known as “acclimation”, which is a sort of “emergency mode” that the plant goes into when it’s subjected to stress or sudden shock due to a change in environment. 

Acclimation is also accompanied by various symptoms that you might witness, such as drooping and falling leaves.

Like going dormant in Winter, this discoloration isn’t permanent. Simply, remove the wilted flowers and continue caring for the plant until it regains its strength and blooms in full color again!

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6. Inadequate Weather 

Mums will do best when you grow them in a moderate climate that leans toward warmth, especially if you live up north where temperatures are quite low during the fall.

While the plant is quite hardy and can survive a wide range of temperatures, they’ll quickly succumb to extreme cold and turn brown just like in winter.

When it comes to chrysanthemums, if you want to achieve the fastest rate of growth, you should keep them at a temperature range of around 65 to 70 °F (18 to 21 °C).

Similarly, the plant will also thrive in relatively high humidity that is anywhere between 70% to 90%. 

Remember to provide excellent aeration to avoid root rot and fungal infections at such high humidity.

7. Too Much or Too Little Fertilization

For optimal growth and blooming, you’ll need to add essential nutrients to the soil during the growing season and 

The most essential elements to consider are nitrogen and potassium, which are found in many purpose fertilizers out there.

Excessive fertilization can cause a lot of problems, such as attracting pests and overwhelming the plant. 

Ideally, an established plant should be fed from spring to mid summer to avoid the impact of winter frost on the new growth.

8. Pests and Insects Infestations

Aphids, on the shoots of a plant

Like most plants out there, Chrysanthemums are also prone to pest infestations, especially when they’re not properly cared for, and some of these pests will cause the flowers to discolor and wilt.

The most popular pests that attack Chrysanthemums are aphids, especially the Macrosiphoniella sanborni

These are small insects that suck the sap of plants and cause stunted growth as well as obvious discoloration to the leaves and flowers of the plant.

In addition to aphids, there are also snails, slugs, and earwigs, which also feed on various parts of the plant, causing obvious brown discoloration.

If you find any of these pests around the plant early on, you’ll save your plant by spraying a pesticide solution that is capable of killing them. 

After that, remove the severely damaged parts and the plant should return to its tip-top condition in a few weeks.

9. Bacterial and Fungal Diseases

Lastly, in addition to pests, the plant can also be infected by various microscopic organisms, such as bacteria and fungus, which also cause visible damage to the plant, including brown discoloration of the flowers.

Among the most popular infections that will turn the flowers brown is Leaf Spot Disease

This one is caused by a bacteria known as “Pseudomonas cichorii”, which puts the plant in a weakened state and is characterized by the spots on its leaves.

Similarly, fungal diseases such as “Fusarium Wilt” and “Root Rot” can also cause discoloration of the flowers. 

These are usually serious conditions that require specific antifungals. But even then, you may not be able to save the plant from dying permanently.

Final Thoughts: Why Are My Mum Flowers Turning Brown?

This marks the end of today’s guide about chrysanthemum flowers and why they turn brown and wilt. 

As you can see, chrysanthemum flowers can turn brown due to a wide variety of reasons, whether they’re natural reasons, inadequate growing conditions, or diseases and infections that cause the flower to turn brown.

Luckily, there’s a reason why the perennial plant is called “hardy mums”. 

If the plant isn’t severely damaged and the browning isn’t due to natural causes, you might be able to save your flowers by cutting off the affected parts and fortifying the soil to encourage new and healthy growth.