Why is my Cactus so Skinny?

If you've noticed your cactus looking a bit strange lately, with thin and stretched-out growth, then it may have fallen victim to what is called etiolation. In this blog, we’re going to go over what etiolation is, the physical signs of what it looks like, and what to do if this happens to your cactus.

What is Etiolation? - Healthy vs Etiolated Cactus

Let’s start by comparing these two cacti side by side. The cactus on the left has maintained its thickness throughout its stem with slow and steady growth, while the cactus on the right is showing much skinnier growth at the tip compared to the rest of its stem. This is what is called etiolation, and is characterized by thin, fast, and weak growth. It is the number one most common problem we see in cactus care but don’t worry, this is fixable.

Why Does it Happen?

1. Lack of Light: The most common cause of etiolation is a lack of light. This causes the cactus to stretch out with thin & fast growth as it reaches out for more sunlight. Cacti need a ton of light to photosynthesize into energy, so if its not getting enough it will eagerly seek out more.
2. Too much Fertilizer: Another reason your cactus might be stretching out and becoming skinny is an overuse of fertilizer for the amount of light it’s getting. Very nitrogen heavy fertilizers can also cause them to grow too quickly. When over-fertilized, cacti receive an excess of nutrients, which promotes rapid growth. And without adequate light, this rapid growth becomes unsustainable and leads to weak, elongated stems.
3. Flowering: Another cause for etiolation might be that the cactus is going through its flowering period in which it directs energy towards flowering instead of normal growth. This is a natural process that can result in some mild etiolation, and should be no cause for concern. Once the flowering period is over, the cactus should return to regular growth. 
   
4. Unturned Cutting: One last common cause could be that a cactus cutting has been left lying on its side for an extended period of time without being rotated. In such cases, the tip of the cutting will begin to curve upwards towards the light source. This response is a natural adaptation seen in cacti that grow tall and occasionally topple over in the wild, as the fallen cactus will continue to grow by curving upwards to seek light.
   

Physical Signs of Etiolation

The physical signs that your cactus is experiencing etiolation are:

• Skinny Thickness: The thickness of the stem is much skinnier.
• Smaller Spines: The spines on the cactus are smaller and less pronounced.
  
• Pointed Tips: The tip of the cactus has become more pointed and angular as opposed to a rounder, more flat shape.
  
• Pale Color: Sometimes the color of the cactus may also become paler, but do not use this alone as a sure sign of etiolation as new growth can also express a paleness in color.
  

Moderate vs Severe

Ideally you’ll catch mild etiolation as soon as possible and place your cactus in more light, but etiolation that goes unnoticed can range from moderate to severe. More moderate etiolation has skinny growth that can usually be fixed, while severe etiolation has more extreme changes in diameter with fast, weak growth longer than around 6 inches. We will go over ways in which to handle the degrees of etiolation that can occur with cacti in the next section.

How to Fix Etiolation

The best way to fix etiolation is to give your cactus more light! Gradually introduce your cactus to more light until you can reach a good intensity; ideally you’ll want at least 10 hours of intense sunlight a day. Then give the plant time to develop new growth. If growing indoors then grow lights will most likely be necessary to completely eliminate etiolation, so make sure to find some lights with decent wattage, and put your cactus in the brightest spot you can find in your home.

 

We also recommend switching to a more balanced fertilizer with less nitrogen in the ratio of ingredients, if over-fertilization is a factor for you. Something with a 1:1:1 ratio of nitrogen (N), phosphorus (P), and potassium (K) is recommended.

Very mild etiolation isn’t usually cause for concern, but if you’re dealing with more moderate to severe etiolation, then an alternative option to introducing the cactus to more light is giving the tip a chop. If the etiolation is more severe feel free to toss the cutting, and let new offsets grow from the mother plant. If it’ isn't so bad then you can keep the cutting, and either graft it or replant it. We have in-depth guides for taking and planting cuttings, as well as grafting cacti in The Source Blog.

Middle-Section Etiolation

Sometimes you have a cactus that has thicker growth at the top and bottom of the stem, but maybe a section of narrow growth in the middle from a period of time it wasn’t receiving enough light. You can leave this as is if you don’t mind how it looks. Something to take into consideration would be that more significant etiolation might impact the stability of the cactus. 

We decided to take one of our plants that was growing like this and cut it at the bottom of the etiolated section. We will leave the mother plant to heal and grow new offsets, and we will place our top cut in a dry, well-ventilated area for a few weeks to callus before planting in soil.

Conclusion

Understanding and addressing etiolation is crucial for maintaining healthy cacti. By ensuring your plants receive adequate light, using balanced fertilizers, and monitoring for signs of weak growth, you can prevent and correct etiolation. Cacti are resilient, and with proper care, even etiolated cacti can recover and thrive.

Key Takeaways

• Etiolation is thin, fast, and weak growth in cacti, commonly caused by insufficient light.
• Other common causes of cactus etiolation are an overuse of fertilizer, nitrogen heavy fertilizers, flowering periods, and extended time spent on one's side.
• Physical signs of etiolation are: skinnier stems, smaller spines, pointed tips, and a paleness in color (not on it's own).
• Severe etiolation has more extreme changes in diameter with fast, weak growth longer than around 6 inches.
• To fix etiolation, gradually introduce a cactus to more light, use balanced fertilizers, and prune severely etiolated parts if necessary.