Why Is My Cactus Turning White

Cactuses are popular among plant lovers because of their low-maintenance requirements and ability to endure high temperatures.

This can make it easy for homeowners to neglect these beautiful plants — which can ultimately begin to show in the plant’s appearance in various ways, such as whitening of its color.

There can be several reasons why a cactus may be turning white, so if you are looking for answers to why did my cactus turn white, keep reading to find out.

Why Is My Cactus Turning White

A cactus turning white is usually a signal from the plant that something is lacking with its maintenance and care routine. Cactus owners must discover why their cactus stem is developing a white hue and take quick measures to prevent it from further deteriorating.

Here are a few possible causes behind why a cactus may become white.

Lack of Sunlight

Sunlight is essential for all plants since it allows them to create energy through photosynthesis. Since most species of cactuses are native to desert lands, cactus plants love bright and sunny spots. 

Therefore, if you have placed a cactus in a spot with insufficient lighting, your cactus stem can turn white and look unhealthy due to starvation. 

Since south-facing windows get the most sunlight during the day, keeping your cactus plant near a south-facing window is the best way to ensure its light requirements are met. 

You must provide your cactus with at least four hours of sunlight a day, and if you live somewhere with ample sunlight, you can offer your cactus up to 12 hours of light daily. 

However, there are other factors, like the specie of cactus, that you must consider to determine how much sunlight will be sufficient for your plant. 

If you get under four hours of sunlight daily, taking additional measures is critical to avoid issues like the whitening of a cactus stem. Thankfully, there are other ways that you can provide your plant with light. 

One of the best methods is to invest in plant growth light. These lights emit frequencies identical to sunlight and can help cactus plants survive in low temperatures during wintertime.

Sunburn

Although cactuses are sun-loving plants, prolonged exposure to extreme sunlight can cause them to get sunburned and develop a white hue. Since cactuses are found in the desert, it is easy for plant owners to believe that exposure to extreme sunlight can benefit them.

However, some cactus species have weak stems, which can easily get damaged and suffer sunburn due to harsh sunlight. This is why cactus owners must understand that although cactuses prefer direct bright sunlight, anything in excess can damage a plant.

If you think harsh sunlight exposure is the reason behind your cactus turning white, you must take quick action to prevent your plant from suffering further.

A great way to protect your cactus from the harshness of sunlight during the peak hours of the day is to keep it at a distance from the window or place light sheers on the window to filter out the sunlight.

You can also water your cactus more if it is summertime since exposure to high heat can cause your cactus to become dehydrated. These measures can slowly help your cactus heal and return to its original color.

Improper Watering

Did you know that many species of cactus plants can survive for months without water? However, a lack of water for an extended period can cause these plants to develop a white color.

Therefore, plant owners need to create a healthy watering schedule for their cactus plants to avoid issues like under or overwatering.

A cactus that is being overwatered will have excessively wet soil and show signs of wilting. In contrast, an under-watered cactus will have shriveled stems.

If you believe your cactus is turning white due to improper watering, the best way to help your cactus heal is to determine if over or under-watering is the reason.

If your plant is turning white due to under-watering, give it ample water and increase the frequency of watering. If you suspect the issue is overwatering, allow your plant’s soil to dry completely before watering it again.

Important note! Cactus owners must have to alter their watering schedules according to seasons. You may have to water more frequently during the summer and reduce the times you water your plant during winter.

Exposure to Harmful Chemicals

Sometimes exposure to harmful chemicals may be a reason behind a cactus stem becoming white. In most cases, pesticides with harmful chemicals are the culprits behind this issue.

This is why it is recommended not to use commercially sold pesticides since they may contain harmful chemicals that cause significant damage to your plant. Instead, stick to organic pesticides like neem oil to eliminate pests in your cactus plant.

Moreover, certain commercially sold fertilizers also contain toxic chemicals like chromium, copper, arsenic, cadmium, mercury, nickel, zinc, zinc oxide, selenium, silver, and thallium. Therefore, you must always inquire about the ingredients in a fertilizer before purchasing it.

Unfortunately, it can be difficult for an inexperienced individual to determine how to treat a cactus suffering from exposure to harmful chemicals.

If you suspect your cactus is turning white due to this issue, the best route of action is to call a professional at your local garden. They may be able to determine if your cactus has chronic exposure or acute toxicity and suggest a treatment plan accordingly.

Diseases

Although cactuses are not highly susceptible to disease, they can develop these issues due to inconsistency in their care regime.

For example, overwatering can cause cactus plants to develop a fungal disease called root rot which can cause fatality if not detected and treated early on.

Color changes are a common sign of root rot. Therefore, if you suspect your cactus is turning white due to root rot, you must immediately inspect the plant for signs like foul odor, black spots, or soggy leaves.

You can also carefully remove your cactus from its pot to inspect the roots. If the roots have turned black or dark in color and have a bad odor, they are likely rotten.

The next action you must take is to immediately cut the rotten roots from the plant with the help of clean sheers and re-pot the plant. Here is how you can re-pot a cactus:

  1. Rinse your cactus pot well
  2. Now, place your cactus plant in the pot
  3. Hold the cactus straight up and gently add well-draining soil (made specifically for cactus plants) around the roots. Avoid Filling the pot with too much soil to avoid compacting the cactus roots
  4. Now wait for at least a week before watering to help the plant heal
  5. Your cactus will slowly begin to revive

Pest Infestations

Besides diseases, cactus plants can also develop pests if not cared for properly. Scale insects, ants, and mealy bugs are some of the most common pests that can attack a cactus.

These pests are drawn towards the sap of cactus plants which they love to feed on. When these bugs cover the cactus, it may appear that it has turned white. This is common because when these insects attach to a cactus, they produce honeydew, which attracts even more bugs.

Therefore, spotting pest infestations early on is critical to prevent the plant from suffering significant damage. The easiest way to treat pest infestations in cacti is to wash the plant and treat it with neem oil carefully.

Temperature Shock

As discussed above, cactus plants thrive in warm and sunny desert environments. Therefore, if exposed to low temperatures, they can suffer from temperature shock, which can cause changes in color.

This is why it is recommended to keep cactus plants indoors when the temperatures begin to drop at night. Even a few hours of exposure to freezing temperatures can cause significant damage to a cactus and even lead to fatality.

If you live somewhere with cold temperatures, keeping your cactus indoors where there may be heating can help the plant thrive.

Moreover, avoid placing the plant in front of air conditioning units or windows that may blow in cold air since these factors can also cause the plant to suffer from temperature shock. Making these changes will eventually help your cactus heal.

If certain parts of the cactus are highly damaged, you can also clip the damaged parts to encourage new and healthy growth. Placing a cactus that may have suffered temperature shock in a spot with bright sunlight can also help speed up the plant’s recovery process

Over Fertilization

In some cases, an excess amount of minerals due to over-fertilization can also cause cactuses to stem from developing a yellowish-white color. According to experts, it is best to fertilize cactus plants once a year since they do not have high fertilizer requirements.

Therefore, if you have been feeding your cactus every other month and are now left wondering why did the cactus turn white, overfeeding may be the culprit.

The best thing you can do for an over-fertilized cactus is to flush out its soil and provide it with a fresh and well-draining potting mix. Furthermore, avoid fertilizing your cactus for a few months after re-potting to allow it to recover.

Always opt for a half-strength fertilizer solution for your cactus plants, and give them plenty of water afterward. Moreover, its good practice not to fertilize a cactus until it is in the active growing stage. 

Basic Care Tips to Prevent Cactus from Turning White

Following the tips below can help prevent your cactus plant from turning white and allow you to preserve its unique coloring:

  • Use appropriate pots with drainage holes for your cactus plants to ensure proper drainage
  • Use well-draining soil made specifically for potting succulents like cactuses
  • Create a proper watering schedule for your cactus and allow the soil to get dry before watering again
  • Regularly inspect your cactus plant for pest infestations and separate a pest-infested cactus from your other plants to prevent a breakout
  • Treat pest-infested cactus plants with organic pesticides like neem oil to prevent exposure to harmful chemicals
  • When applying the neem oil solution on cactus plants, make sure to place the plant in a shaded area to prevent it from burning
  • Water more during extreme heat — when the soil is 90% dry
  • Protect cactus plants from exposure to harsh sunlight
  • Keep your cactus clean to avoid dust buildup, which encourages fungal growth
  • Re-pot your cactus plants every two to three years
  • Avoid choosing fertilizers with high proportions of NPK

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Final Verdict

Cactus plants make an excellent addition to plant lovers’ collections, and their low-maintenance requirements make them a favorite for many. However, sometimes cactus owners may complain: why is my cactus turning white?

When this happens, one must consider factors like improper watering, over-fertilization, lack of sunlight, pest infestations, diseases, temperature shock, exposure to harmful chemicals, and sunburn to find the reason behind the whitening of color.

Finding out why your cactus might be turning white can help you correct the issue and help the plant return to its natural color.