A purple cactus can be caused by many factors. Some cacti naturally turn purple, but it can also be a sign that something is wrong. Find out why your cactus is turning purple to help it thrive.
In most cases, the cactus turns purple in response to environmental stress. Too much sun, temperature problems, root rot, nutritional deficiencies, overcrowded roots, and cactus cysts are all possible causes. In addition, your plant can be perfectly healthy and adapt to new conditions.
cactus that turns purpleContents
Is a purple cactus cause for concern?
If your cactus turns purple, it’s not always a sign of a major problem. It is normal for some types of cacti to turn a little purple.
It is a natural part of their life cycle when they experience cold and dry conditions.
Could it be fruit?
If you have a nopal, you may be lucky. It’s possible that the purple spot on your cactus is actually a fruit!
Tunas are sweet fruits used in many Mexican cuisines. Their color varies from green to reddish purple and can be seen as a discolored spot on the cactus.
Causes of Cacti Turning Purple
A color change becomes a concern if many of your cactus’ leaves are noticeably purple.
Other signs of a problem include wilting, stunted growth, or waterlogged foliage. Determining the cause of the color change is important to determine if your plant is in serious danger.
Cacti change color when stressed. Cacti contain a purple pigment called betalain, which they produce more of in response to stress.
Let’s review the possible causes and find out how to treat them.
too much sun
While cacti have evolved to adapt well to sunlight, the ones you have around the house may struggle to adapt.
Store-bought cacti are usually grown in the shade in a greenhouse. This means that they are not used to so much direct sunlight.
Cacti need bright light, but indirect, diffused light is best. Suddenly exposing a cactus to bright light can burn its skin and turn it a reddish-purple color.
If your cactus is new or if you recently moved it to a sunnier location, chances are it has sunburnt.
How to Treat Sunburned Cacti
Fortunately, the solution to sunburn is relatively simple. Move your cactus to a location that receives less direct sunlight.
Don’t move it to your basement just yet – cacti still need lots of sun!
Light falling directly on the plant, for example through a south-facing window, is direct sunlight.
The other windows in your house provide indirect sunlight that is more diffuse and more pleasant for the plant.
Moving your plant to a window that faces a different direction can help with scorching sunlight.
If you only have south-facing windows, try making your own sunscreen. Simply place a paper towel over your cactus to give it much-needed shade.
temperature problems
Purple leaves can be a sign of temperature stress. Cacti sometimes turn purple-red when their roots overheat.
Cacti can also turn purple if they get too cold. If the plant suffers frost damage, the cells burst and can no longer hold any liquid.
How to cure heat stress
The ideal temperature is somewhere in the middle, so it’s important not to place your plant in extreme temperatures.
To prevent your cactus from getting too cold, keep it away from drafty areas, such as open doors and windows. Also avoid places that get too hot and dry, such as fireplaces and heating ducts.
Since the plant’s roots are more likely to overheat, store your cactus in a container that will stay cool. Avoid black plastic pots and opt for a material like clay.
rotten root
Purple leaves can also be a sign of root rot, which results from overwatering and poor drainage.
If the soil stays wet for too long, the roots of the plant will die and can no longer absorb water or nutrients like magnesium. As a result, your cactus may turn purple.
How to Fix Root Rot
Start by pruning the damaged roots and leaves with sterile shears, removing as much waterlogged soil as possible.
Transfer the plant to a sterile pot with fresh potting soil. Do not water the cactus for a few days after moving it, and allow the top inch of soil to dry out between waterings.
Root rot is usually the result of overwatering. I wrote an article on how to do it. save your overloaded cactus. You will also learn how to water them properly.
nutritional problems
One possible reason your cactus is turning purple is that it lacks the nutrients it needs to survive. If your plant is wilting and turning purple, it could be a sign of magnesium deficiency.
Christmas cacti in particular are at high risk for magnesium deficiencies. That being said, all types of cacti are susceptible.
How to deal with eating problems
If your cactus lacks magnesium, fertilizer is the solution. You can buy a fertilizer enriched with magnesium, but you can also DIY with an Epsom salt treatment.
To make a magnesium treatment, combine the following ingredients in a spray bottle:
- Eight tablespoons of Epsom salt
- Two and a half liters of water
- A drop or two of dishwasher
Use a spray bottle to mist the leaves of the cactus, making sure to cover the undersides of the leaves as well. Continue to use the spray mix every two weeks until your cactus returns to its normal color.
overgrown roots
Clogged roots are another possible reason for your cactus changing color. Growing a plant in a container that is too small can cause the roots to pack too much or “cling”.
Plants with roots cannot adequately absorb water and nutrients from the soil. Lack of nutrients can cause leaves to turn purple in response to stress.
How to Fix Overgrown Carrots
Over time, your cactus’ root system will also grow and it may no longer fit in the pot it used to be.
If you notice parts of the roots trying to stick out of the drainage hole, it’s time to transplant the cacti into a larger container. Normally plan to transplant your cactus every 3-4 years.
If your cactus’ roots have become overcrowded, you will need to move it to a larger home. As a general rule, you should transplant cacti when you can see their roots through the drainage holes in the bottom of the pot.
For faster growing cactus species, it usually takes two to three years. Slow-growing cacti only need to be transplanted every three to four years.
Not all types of cacti have the same needs, so it’s important to research the ideal conditions for your cactus.
For example, certain types of cacti, such as Christmas cacti, do well when they have overcrowded roots.
For this reason, a Christmas cactus should not be transplanted unless it has been in the same pot for at least a few years.
Here are the steps to transplant your cactus:
- Before transplanting your cactus, be sure to wear heavy gloves to protect your skin from the plant’s sharp thorns.
- Check the plant and soil for pests or signs of disease.
- Select a new container one size larger than the old one
- Place gravel in the bottom of the pot to aid drainage and sprinkle a thin layer of gravel over the surface of the soil.
- Allow the soil to drain before resuming your regular watering schedule.
Source: San Jose Cactus and Succulent Society
cactus cyst
A purple cactus could also be a sign of infection. It is possible that your plant is infected with a pathogen called Cactodera cacti, more commonly known as cactus cyst.
Cactus cyst occurs when a cactus is planted in infected soil. Reddish-purple leaves, stunted growth and wilting are possible signs of infection.
However, the most obvious sign of a cactus cyst are small white balls that appear on the roots of the plant. (Source: Plantwise Knowledge Base)
You May Also Like: Black Spots On Cacti (How To Treat, Identify & Prevent)
Cactus Cyst Treatment
It is very difficult to treat the cactus cyst once it has infected the plant, so it is best to focus on prevention. To prevent your cactus from getting sick, plant it in clean, sterilized soil in a new pot.
If your cactus is infected, it’s best to throw the plant away. As difficult as it may be to get rid of your beloved cactus, it’s important to prevent the infection from spreading to your other plants.
Have you ever had to deal with a cactus that turns purple? What caused it and what did you do to revive your plant?
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