Why Are My Cactus Needles Turning Brown?

Cactus is known to be a hardy plant and  that shows itself in the way it grows comfortably without any need for any attention. However, there are times that you would find the cactus needles turning brown. What causes the cactus needles to turn brown and how to fix it? We will find that out in today’s post.

There are several reasons for a cactus needle to turn brown. Most of the cacti chage color to brown as they grow older. if you observe the cactus turning brown or yellow from top to bottom, it can be due to the sun burn or exposue to a high degree of sunshine. The yellowing or browning from the bottom to top can indicate a root rot. 

What causes the Cactus to go brown or yellow? Some possible reasons include – 

  • Cactus corking is one more reason why the brown rind is found at the bottom of a healthy cactus plant.
  • Spines near the soil rich in humus can turn brownish. One more reason can be that the plant has perished from the lower part.
  • Brown needles on your cactus plant can worry you as to why are my cactus needles turning brown even after taking good care of it.
  • Spines near the soil rich in humus can turn brownish. One more reason can be that the plant has perished from the lower part.

Whenever you find your cactus needles turning brown, look for the reasons like excessive sun exposure, root rot, or pest infestations. Our experiecne has shown us that taking acctions to take care of these aspects and factors helped us prevent the premature dying of the plant. 

Why Are My Cactus Needles Turning Brown?

A few priamry reasons that can cause the cactus to go brown can include the following. When we undertook a research into the possible causes of the needles turning brown, we found that the root rot was the priamry cause for the cactus turning brown.

Root Rot

The primary symptom of root rot is when the acrus begins turning brown from the bottom. Once the root rot sets in, it may not be easy to save the plant in most of the cases. 

It is quite common to overwater a plant, and doing so with a cactus will result in the root rot.  Ultimately, roots turn mushy, making them unable to aid the growth of the plant.

Initially, you may not find anything amiss. But, soon it spreads, making the stem soft, pale and the bottom changes to brown.

The plant can perish if you do not resolve this issue in time. Root rot can occur if the potting soil is not well-draining, thereby retaining more water. 

Why Are My Cactus Needles Turning Brown

Moreover, the pot without drainage holes or blocked drainage holes can also be one of the reasons that can result in root rot. 

How to fix or address root rot in cactus? 

Root rot is not easy to figure out as the symptoms appear only when a major part of the root is destroyed. Start checking the roots once you notice the brown needles along with the brown cactus base.

If you want to learn from our own experience, we followed the following procedure to fix the root rot to some extent and could savve at least a few plants. Do note that you may not be able to save all the plants where the root rot has set in.

  • Remove the damaged portion with a sharp knife and use sulfur powder for healing.
  • Take out the plant from the pot and change the soil before replanting the cactus.

The plant will flourish again into a healthy plant.

In case, the root rot has caused much damage with a small healthy part left, cultivate a new cactus plant. To avoid root rot, do not overwater the plant. Also make sure that the soil is oxygenated and well-draining. Keep checking the drainage system to drain the excess water from the pot. If you find any blockage to the drainage, they should be cleaned up instantly. 

Sun Damage

If you notice the cactus is turning brown from the top, it would indicate a sin burn or sun exposure. That may appear a little unintuitive but not every cactus thrives in hot sun despite them being dessert plants. 

As cacti love to be in the sun, it’s impossible to believe that excessive sun can damage them. Also, these plants thrive in desert areas in scorching heat. However, there are a few cactus species that do not like hot sun or sun exposure for longr durations.

If you have recently brought a cactus from a nursery or a shaded place, it is advisable to introdcue it to bright light in a gradual manner. As part of our exposure to different types of cacti, we found that it is a good idea to keep your cactus plant in partial shade with limited sun shine.

While buying a cactus plant from a nursery, keep it in shade for some days and expose it slowly to the sun.

If the browning is occurring at the apex and spreading to the other plant parts, the sun is the reason behind it. The browning can be slow with less damage forming a white tinge on the sun-facing portion.

When the plant is exposed to the sun for a prolonged period of tile, it will turn the white spots into brown scars, which can be  irreparable.

If you notice the spots well ahead of time, you can consider shifting the plant to a shaded area or even to a partially shaded area. You can also use curtains if you have sun facing windows. 

Heat Damage

If you notive the browning on the sides or only on one sie, it can be due to a heat source or heat damage. You may need to check if you have any heat source in the respective direction. 

it may be possible that the browning is caused by your heat vents. In some cases, the airconditioner radiators may be the cause for concern and can cause the browning in cactus. If you find anything closer to your cactus and you witness a browning symptom on that side of the plant, it may be necessray to shift the cactus to another area which is not affected by the heat sources.

Also, placing the cactus plant near a window where hot air and cool whiff constantly enter the room, can harm the plant.

Very Low Temperatures

The frost damage in the cactus is likely to happen in the plants that are in direct contact with the window glass. On analysing the root couse for the problem, we found that the low tempertures cause the cells in the cactus to rapture and thus result in browning. 

The sun and frost, both can harm your plant. In areas with snowy winters,  protect your plant by placing it at a distance from the window and maintaining the temperatures in your house.

If the plant tissues remain in the excess cold, the cells rupture, and calluses are formed for healing the cells that look brown. On noticing such changes, shift your plant to a safer place inside your house. In most of the scenarios, it is observed that the plant heals itself. However, if you belong to an area that has a chilly weather for most part of the year, it is advisable to shift the plant to a dry and warmer area.

Scale Infestation

Scale infestation manifests itself in the browning of the plant in some random areas. The scales are brown insects that go unnoticed as they appear as brown spots on the stem. 

These insects have rigid coverings that suck the cacti sap, thus making your plant go weak. Infected parts look yellow or brown, and continue to go pale.

This issue should be addressed as quick as possible as a slight delay can spread the scales to the other parts of the plant, ultimately killing it.  On noticing scales, use either natural or chemical means to eradicate them. The scales can be easily removed using a mixture of detergent and water as well. Our studies have proved that using the water and detergent mixture is a preferred option as opposed to the use of chemicals that may damage the plant or result in other issues. 

Yet anothr excellent option is to kill the insects by using horticultural oil that stops their oxygen supply, thereby killing them.

You may also use an insecticide, if the pest infestation has spread into a larger part of the plant or more than one plant.

Mite Infestation

If you notice the browning at the place where a new growth is ahppening, it would be a clear indication of mite infestation. Our extensive study has revelaed that the Red Spider mites are one of the most widely observed culprits among these mites. 

In cacti plants, along with the sun damage, mite infestation also occurs as browning starts at the apex. The difference between sun exposure and mite infestation can be that in the case of mites, you would notice the browning at the point where new growth appears. 

These mites feed on the fresh growth occurring at the top, and then leaves rusty brown spots on the plant. These mites are very minute, hardly visible with naked eyes and are very destructive in nature, thus killing the plant.

Look for such spots and the webs on the plant. You can use homemade insecticides or chemicals depending upon the level and extent of infestation.

Why Are My Cactus Spines Turning Black?

 A few common causes that can turn your cactus spines black can be over exposure to sunlight, insufficient light, low temperatures, lack of nutrients and lack of ventialtion. Some diseases and over fertilisation may also turn it black in many cases. 

Some cactus species have a natural phenomemnon where you may find the spines turning black after rains. It may not be necessary to worry about the plants if your cactus belongs to one of those species. 

Mostly, black spines on your cactus should not make you anxious.  In species like the Saguaro cactus, black spines can be due to the monsoon rains.  You can be at ease as the cactus spines will change back into their natural colour as the spines dry.

If the environment around you is damp, keep your cactus indoors as it cannot survive the continuous rains that can cause root rot that will kill the cactus.

How to water a cactus having black spines?

The rule of thumb that one needs to follow when warering the cactus is to let the water dry out completely in the soil and then water it again. They can thrive withe little water, but not NO water. 

After watering the cactus adequately, the spines may turn black. It will resume back to normal as the soil dries except in certain cases where the water regularly moistens the soil. Water your cactus thoroughly with proper drainage. 

In deserts, it rains heavily soaking your cactus thoroughly. However, for most part of the year, there is no rain and thus your cactus is not accustimd to the consistent rain or consistent water. That is exactly why some cactus species turn black when overwatered. 

What If  The Cactus Turns Black?

A cactus generally turns balck due to fungal or bacterial infection. A few possible causes can be bacterial necrosis, crown rot, and phyllosticta pad spotting.  If you notice any such infection, make sure that you have removed the infection as that would help you avoid the spread of infection to any other part of the plant. 

You can follow the steps here below if you find cactus turning balck –

  • Cut the black parts of the cactus with a sharp knife or shears.
  • Ensure that the knife and the shears are sterilized properly before and after the pruning so that the infection does not spread further.

Black Spines Indicate The Initiation Of Maturing 

Mostly, black spines on the cactus means that the cactus has started maturing. You should be cautious if you want to transplant the cactus from its pot at this time. More cacti are killed during transplanting the adult cacti. As you transplant the cactus, do it carefully as you don’t want to kill the cactus.

A cactus that gets less sunlight should be slowly introduced to bright sunlight or it can get sunburns or black spots on your cactus.

Bonus Reading – Why cactus changes colours? 

Cactus spines can change colour like brown, yellow, red or black. Mostly, cactus spines change color when they mature. 

Cactus Spines Turning Red

Cactus spines turn red at some point in their life as the plant goes through a natural growing period.

Red spines show that your cactus plant is thriving. Once you notice your cactus spines turning red, give them some more water to help the growth.

If your cactus is watered adequately and is well cared for, there are more chances of seeing red spines. It shows that you can continue with the same routine for your cactus as you are on the right track in taking care of your cactus.

When the cactus is growing, red spines can turn white before embracing other colours as it is a part of the growth.

Before we say bye…..

As you would have observed, there are several reasons that can make a cactus turn brown. Analysing each of the reasons and applying the necessary fixes would help you take care of your beloved succulent and ensure that it thrives for a longer period of time. It is always importnt to check out the underlying causes for the browning and then mmoe on to fix the issues if any.

A few FAQs

Why is my cactus turning yellow? 

A cactus turning yellow may be an indication that it is dying. One of the most possible causes can be the root rot that can happen due to overwatering. Another reason can be the sun exposure. In some cases, an aging cactus may also show the yellowing or browning signs before it dies.

Can you revive a brown cactus?

If the browning of the cactus has been due to root rot, it may be quite difficult to save the plant. However, if it is due to the sun exposure, mite or scle infestation and other causes, you can take a timely action to to save your plant.

Why is my cactus turning brown on the edges?

This is called corking and is quite common in an aging cactus. If you observe the browning from top to bottom, it should be a sign of sunburn and not corking.


Nikita is a Succulent lover. She really enjoys planting and nourishing them. She loves to share information about various Succulents on this blog to aware people more about these awesome plants.

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