Why Are My Cactus Needles Turning Brown?

Cactus spines mostly change color as they grow older. If cactus spines turn brown from the apex, sunburn can be the reason. But, if cactus needles are turning brown near the stem, root rot is the reason behind it.

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.

Why Are My Cactus Needles Turning Brown?

Root Rot

Often, we give more water to the cactus than required leading to an accumulation of water and the roots are unable to absorb nutrients. 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 brown.

The plant can perish if you do not resolve this issue soon. 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 is also to be blamed.

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.

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 and the soil should be oxygenated and well-draining. Keep checking the drainage system to drain the excess water from the pot.

Sun Damage

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. It is a good idea to keep your cactus plant in partial shade with limited sun.

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 in the sun for more time, the burning will turn the white spots into brown scars, which are irreparable.

If you see white spots on time, you can save the plant by shifting it

to a partially shaded area. You can also use curtains on a sun-facing window.

Heat Damage

Outdoor plants are prone to animal attacks, excessive sun exposure, and frost. An indoor plant is also prone to some miscreants like your heat vents as keeping the cactus closer to the heat vent or the air conditioning vents will damage your cactus plant. 

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

You can easily find if indoor conditions are causing harm as

browning will be on the side closer to the vent. In such a case, place your plant away from any vents.

Very Low Temperatures

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.

Scale Infestation

Brown spots on your plant can be due to scales that are small insects with rigid coverings that suck the cacti sap, thus making your plant weak.

Infected parts look yellow or brown, and this issue should be addressed fast or they will attack larger parts of the plant.

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.

Or, kill the insects by using horticultural oil that stops their oxygen supply, thereby killing them.

Use an insecticide, if the pest infestation has spread into a larger part of the plant or many plants.

Mite Infestation

In cacti plants, along with the sun damage, mite infestation also occurs as browning starts at the apex.

These mites feed on the fresh growth occurring at the top, and rusty brown spots are left. These mites are very minute, hardly visible with eyes and are very destructive, thus killing the plant. Look for such spots and the webs on the plant.

You can use homemade insecticides or chemicals depending upon the infestation.

Protect your cactus needles from turning brown and  dying by giving it an ideal atmosphere to grow and look for any sudden changes.

Why Are My Cactus Spines Turning Black?

Your cactus spines are turning black because spines of some species naturally turn black after rain. Seeing black spines, you may ponder that despite taking all care, why are my cactus spines turning black.

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?

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. Then there is no rain for a long time period.  

What If  The Cactus Turns Black?

The cactus will turn black due to a bacterial or fungal disease turning the cactus black. In such cases, take immediate action as crown rot and necrosis will follow. 

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.

Cactus Spines Changing Colour

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.

So this article is about Why Are My Cactus Needles Turning Brown! Hope you now know everything about it. 


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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