Pencil Cactus Turning Yellow [Symptoms and Remedies]

The pencil cactus, also known as a firestick plant, is surprisingly not a cactus at all. These plants are a type of Euphorbia which is part of the succulent family. It’s unclear how they ended up being labeled a cactus, but the good news is that the general care of firesticks and cacti are quite similar. 

One common issue for cacti and succulents is yellowing leaves and stems. If you have noticed your pencil cactus seems to be turning yellow, there are a few things that could be causing it, ranging from overwatering to aging.

5 Reasons Your Pencil Cactus Is Turning Yellow

Read through these 5 points to quickly identify what is wrong with your cactus and the steps you need to take to fix it.

1. Overwatering

The most common mistake people make with pencil cacti is overwatering. These plants are native to arid regions in Africa and India and don’t do well when kept in humid or wet conditions. 

The ideal watering schedule for a pencil cactus is every other week in spring and summer and once a month in the fall and winter. Light plays a huge role in water absorption, which is why you will need to adjust your water schedule as the days get shorter.

If you notice your plant isn’t absorbing as much water as you think it should be you may need to move it to a more well-lit space in your home. 

Before watering your pencil cactus, you will want to check the soil. Pencil cacti prefer to be mostly dried out before you water them again, so if the soil is still damp it’s best to wait a few days before checking again. 

Another symptom of overwatering is brittle branches or mushy lower branches. Many people may think brittle yellow branches mean your plant is in need of water, but really the opposite is true. If your plant seems to be wrinkly or mushy, you may need to repot it in order to save it. 

2. Root Rot

Pencil cacti are highly susceptible to root rot, so overwatering is a major issue for them. If you feel the soil of your firestick and it’s soggy or wet, your plant may be experiencing root rot.

Remove the plant from the soil and take a look at the roots. Healthy roots should be white and firm, while rotten roots will be dark grey or black and mushy. 

If you have rotten roots on your plant, you will want to remove them either with your hands underwater or with sanitized shears. Once the rotten roots are gone, you can place your plant in new soil and if it has enough healthy roots it should bounce back in a few weeks. 

To prevent root rot from happening again, you will want to use soil that is either specifically formulated for cacti and succulents or potting soil with added perlite. A ratio of 1 part potting soil, 1 part perlite, and 1 part sand is ideal. You will also want to reduce the frequency of your watering. 

3. Aging 

Many plants will lose leaves as they age. This is completely normal. As your pencil cactus grows, the leaves near the bottom of the plant may start to turn yellow.

As long as your soil is dry and everything else on your plant is normal, you can safely assume this yellowing is due to aging. Simply leave the plant alone and it will absorb any remaining nutrients from these branches before they fall off the plant. 

4. Injury

A less common reason for your firestick’s branches to turn yellow is an injury. If someone accidentally runs into your cactus, or something falls on it, your plant may sustain damage that prevents nutrient and water distribution. This will cause the area on the far side of the injury to turn yellow and eventually fall off. As long as it isn’t a large part of the plant, this shouldn’t have any lasting consequences for the health of your pencil cactus. 

5. Not Enough Light

Pencil cacti prefer to be kept in bright direct lighting. Keeping them in indirect lighting or low lighting can lead to poor water absorption, root rot, and a very sad plant. If you are only watering your plant every few weeks, but the soil still isn’t drying out, it’s likely you need to up your lighting. 

To raise the lighting around your pencil cactus, you can either move it directly in front of a south-facing window or add a plant bulb.

If you live in an area that is warm in the spring and summer, you can also place your cactus outside in a sunny area for the growing season and bring it in before temperatures get below 65. T

his will give your plant time in its ideal environment while also keeping it happy and healthy in the colder months. USDA grow zones 9-11 can actually keep their pencil cactus outside year-round and they will thrive. Some have even been reported growing over 30ft, though 6 feet is a more realistic expectation for plants kept indoors. 

Why is my Pencil Cactus Turning Orange/Red? 

For many plants, turning orange or red can be a bad thing, but for a pencil cactus, it is a sign your plant is thriving. 


Pencil cactus prefer high light directly hitting their branches. Unlike many plants that may burn in direct light, the pencil cactus turns a bright red or orange. This is what gives it the nickname firestick.

It can be hard to achieve this look when growing your plant indoors, but if you are determined to work at it you should be able to get enough light in a south-facing window. If your plant is in a south-facing window and still isn’t changing colors you can give it an added boost by adding a plant light above it. 

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About Me

Hi, I'm Joe! I'm the head of SEO and content management at Bloom and Bumble. I'm a huge plant lover and over the years my home has become more like an indoor rainforest. It has taken a lot of trial and error to keep my plants healthy and so I'm here to share my knowledge to the rest of the world.

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