Why Are Your Mums Turning Purple? 6 Reasons

Have you recently decided to obtain a fresh batch of mums, only to be disappointed when you found out that they suddenly changed color? Maybe they turned purple around the tips and edges. Why exactly are your mums turning purple?

Your mums are likely turning purple for one of the following reasons:

  1. Cold temperature
  2. Natural life cycle
  3. Improper care and attention
  4. Harsh weather conditions
  5. Poor quality soil
  6. Overwatering

In this article, I will go on to explore why your mums are turning purple, what you should do about it, and provide you with some steps that you can take to prevent the same from happening in the future. Keep on reading to learn more.

Exploring the Causes of Purple Mums

Mums are really popular – they come in countless types and varieties. While mostly similar, the differences in these varieties can make it hard to pinpoint exactly why your mums turned purple, as it’s dependent mostly on the specifics of the scenario.

Mums turning purple is often a sign of poor health, poor environmental conditions, or externally sustained damage. If your mums are turning purple, there is a high chance there is something that needs your attention.

Don’t worry, though. I will share with you six of the most common reasons for mums turning purple and will give you some tips and tricks later in the article.

For now, here are six reasons why your mums are turning purple:

1. Cold Temperature

First and foremost, cold temperatures will make mums change color. If you have some experience in gardening, you can probably imagine how this works.

Mums are generally not resistant to cold. One of the major struggles faced by those who plant mums later in the season is getting the mums to survive through winter. It is notoriously difficult to make that happen, although still possible.

Cold temperatures – especially at night – can be a likely cause of your mums turning purple. Too much cold can damage your mums and cause them to change into a withering purple. Mums do not do well in temperatures lower than 20 °F (-6.67 °C).

You can be reasonably sure that the cold is what’s causing your mums to turn purple if you live in a very cold environment or have just had a sudden, drastic drop in temperature. Mums cannot handle cold weather events such as frost or snowfall very well.

Aside from turning purple, some of your mums may also turn brown. Unfortunately, this means that your mums have sustained some damage and will need some extra attention if you want them to flourish once more.

To protect your mums from the cold, consider changing their position or covering them during the night to protect them from frost and snow.

2. Natural Lifecycle

Mums, like many other plants, change color as they age. If your mums appear to be developing a purple-ish tint but are not otherwise unhealthy or damaged, then it may just be the case that they are naturally changing color.

It is not uncommon for mums to change color throughout their bloom cycle depending on environmental factors – this is not necessarily harmful. Mums can even bloom back in different colors. 

Keep in mind that mums only bloom for about 4 to 8 weeks. Turning purple later in this duration might also be an indication that they are nearing the end of their blooming cycle, which is natural and does not require you to take any action.

3. Improper Care and Attention

Unfortunately, improper handling and maintenance can lead to your mums being damaged and turning purple. This can be physical damage due to improper handling or accidental bruising, or damage caused over time due to errors in watering or placement.

Regarding placement, keep in mind that mums are one of those plants that absolutely love the sun. You don’t have to be reserved in controlling the amount of sunlight they receive – they are best positioned fully out in the sun. 

Mums thrive in full sunlight. Although you can make do with around 6 hours of sunlight a day, just keep in mind that the more sun they receive, the healthier they will be. And, of course, the health of your mum has a major impact on the quality of its bloom.

The only thing to watch out for here would be excessive heat. If temperatures exceed 90 °F (32.2 °C) regularly, it would be best to allow for partial shade or shade during the scorching afternoon. 

4. Harsh Weather Conditions

Mums are very vulnerable to harsh weather conditions, so this is something you’ll need to keep an eye out for and account for. We discussed how snow and frost are dangerous to mums because they can’t resist the cold very well.

If you live in an area that experiences a lot of snow and frost, then chances are, you often experience hail, too. Hail can cause a great amount of damage and bruising to your mums, so make sure to provide them adequate protection against the elements.

Even rainfall is not entirely safe. Heavy rain can lead to higher than normal water levels and your mums turning mushy.

The best way to deal with said weather conditions is by covering your mums whenever there is a likelihood of bad weather hitting your area.

5. Poor Quality Soil

This is not as applicable if what you have are potted mums, but when we talk about mums planted in your garden, the soil is inarguably a determining factor in their health.

Mums are a little more demanding in terms of the quality of the soil – it needs to be well-filled with nutrients (you can use fertilizers for this purpose) and have good drainage to prevent water from stagnating.

One of the most important factors in determining the quality of your soil is pH.

There is an ideal soil pH range for mums to grow in, which is 6.0 to 8.0, meaning the soil can be slightly alkaline or acidic. Higher or lower than this range is suboptimal for growth and potentially harmful to health.

If you’re concerned about the pH of your soil causing damage to your plants, it may be a good idea to get it checked out and, if necessary, take action to remedy the unnatural soil pH. The good news is that altering soil pH is pretty straightforward and likely won’t cause you much trouble.

6. Overwatering

Overwatering is a potential risk for mums. Unless you are situated somewhere with extreme heat conditions, you should stick to watering your mums once a day. As mentioned before, be careful not to let the water stagnate in the soil.

Take care not to exert water pressure on the plant itself and on the soil instead. 

What to Do if Your Mums Are Turning Purple

If your mums are turning purple but showing no signs of poor health, or you know that they are nearing the end of their blooming cycle, you might not have to do anything and just let nature run its course.

However, if they are turning purple and show signs of illness, it is likely being caused by external factors that could use your attention.

The important things you should take care of, first and foremost, are the growth environment and protection against weather conditions:

  • You want to ensure that your soil is nutritious and lies within the acceptable pH range. 
  • Provide your mums with ample sunlight and shade only if the heat is extreme and persistent. 
  • If situated in a cold area, consider covering your mums overnight to protect them from the cold.
  • Water your mums once a day, and do not water the plant foliage directly.

Final Thoughts

Mums are beautiful, fit well into most household gardens, and are an absolute pleasure to grow for many of us. While they tend not to require much maintenance, they are vulnerable to detrimental environmental conditions. 

If your mums are turning purple, it may signify that something is wrong. If you live in a cold region, it is likely because of the cold; however, other factors can influence the quality and health of your mums, namely improper care, harsh weather conditions, poor-quality soil, and overwatering.

Dr. Moritz Picot

Dr. Moritz Picot is a horticulture enthusiast and the founder of TheGrowingLeaf.com, where he serves as the lead content writer. He established the website in 2022 as a valuable resource for both gardening aficionados and beginners, compiling all the gardening tips he has accumulated over the past 25 years. Alex has a passion for nurturing plants, transforming backyards into inviting spaces, and sharing his knowledge with the world.

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