Why Is Your Cactus Growing Aerial Roots? 6 Causes

The cactus is commonly believed to be easy to care for. However, these plants can be pretty picky, and your cactus might begin to grow aerial roots if you need to correct its growing conditions. So, why is your cactus growing aerial roots, and can you do anything about it?

Your cactus is growing aerial roots due to inadequate watering, excessive humidity in the environment, nutrient deficiencies, or a repotting need. You can eliminate aerial roots by addressing these issues.

The rest of this article will tell you everything you need to know about aerial root growth so that you can give your cactus the best possible care. Read on to learn more information about why your cactus is growing aerial roots.

Understanding Aerial Roots

Before discussing why your cactus is growing aerial roots, it’s worth explaining the concept of aerial roots. Aerial roots grow above the soil. They resemble tiny branches and extend from the upper plant parts instead of below the soil. They are usually brown, pink, or white in color.

If you notice aerial roots growing on your cactus, there’s no need to worry because the roots themselves are not harmful to your plant.

However, the growth of aerial roots is a sure sign that your cactus is not getting everything it needs, so it is using these new roots to address those needs itself.

While you can safely cut aerial roots if the look is bothering you, they will keep growing back. The best long-term solution is to determine what you need to do differently to ensure that your plant gets the best possible care.

Here are some reasons why your cactus might be growing aerial roots:

1. Inadequate Watering

A common reason your cactus is growing aerial roots is that it’s not receiving enough water. 

If you’re not watering your cactus frequently or thoroughly enough, this might cause aerial roots to sprout from the plant’s above-ground parts.

This happens because your cactus is trying to find water from other sources. By growing aerial roots, your cactus can absorb water from the humidity in the air to adapt to dehydration.

While this is a pretty neat survival mechanism, aerial roots are not an effective long-term solution for your cactus, especially if you live in an area that isn’t very humid. Aerial roots are a common sign that you should water your cactus more.

Thankfully, this issue is simple to fix. 


Watering a cactus can be very challenging, and it’s better not to overwater it because these drought-tolerant plants are used to surviving on little water.

However, it’s also detrimental to underwater your cactus, as this can lead to dehydration and the growth of aerial roots.

If you want to solve this aerial root problem, one of the best ways is to ensure that you’re watering your cactus enough.

Cacti typically need to be watered once every 1-2 weeks. However, the pot size and substrate type may vary for each household, so it’s best to check the soil regularly and water the plant as soon as the top half of the pot is dry. For smaller pots, you can water your cactus when the top 3 inches (7.6 cm) are dry.

To ensure that your cactus isn’t dehydrated, I also recommend using a soil moisture meter to measure the moisture levels in your cactus’s soil. If the reading shows 2-3 halfway down the pot, then it’s time to water your plant.

2. High Humidity

If you live in a very humid environment, this can be another cause behind the aerial roots sprouting from your cactus.

As mentioned above, aerial roots can absorb water from the air to hydrate the plant. If your cactus senses excessive humidity in the air, it might sprout aerial roots to obtain more water.

This doesn’t necessarily mean that you’re underwatering your cactus. It might just be due to an overly humid environment, which might cause the air to contain more moisture than the soil in which your cactus is planted.

Luckily, there are a couple of ways to address this issue.


If you’re worried about the moisture level in your cactus’s environment, you’ll need to check the humidity levels. There are multiple ways you can go about doing this.

If you want to measure your indoor humidity levels, you can use a hygrometer, which is a device that is used to check humidity. If your hygrometer tells you that your indoor space is very humid, this might be what is causing your cactus to grow aerial roots.

Below are some tips for lowering humidity levels in your home:

Improve the Air Circulation

Improving the air circulation by opening windows can reduce the humidity in your home. However, if the outdoor humidity is much higher than your indoor humidity, the relief will be minimal. In that case, you can switch on some electric fans.

Buy a Dehumidifier

Purchasing a dehumidifier is one of the best things you can do to lower humidity levels in your home.

A dehumidifier lowers the humidity levels in your home. They are easy to use and come in a wide variety of shapes and sizes so that you can choose from plenty of options. In addition to helping your cactus, a dehumidifier can make your home more comfortable for its occupants.

Removing the high humidity levels from your home can help decrease the chance of aerial roots growing in your cactus.

Acquire Dehumidifying Plants

Acquiring dehumidifying plants is another excellent way to lower the moisture levels in your home.

Some indoor plants that can lower humidity levels include:

  • Spider plants
  • Lilies
  • Pothos
  • English ivy
  • Peperomia
  • Aloe vera

This is an inexpensive, natural, and aesthetically pleasing alternative to purchasing an expensive dehumidifier, and it works incredibly well for indoor spaces.

Take Cooler Showers

Another thing you can do to decrease your home’s humidity levels is to take cooler showers. This is especially important during the hotter months of the year or in high-temperature regions where humidity levels are significant.

Taking hot showers produces a lot of steam, increasing your home’s moisture level. This can be harmful to your cactus, especially if you have one placed in the bathroom.

By taking fewer hot showers every now and then or taking cooler ones, you can lower humidity contributions in your home and help reduce the appearance of aerial roots in your plants.

Use Your Air Conditioner

Using your air conditioner is another simple way to fix the high humidity levels in your cactus’s environment and ultimately decrease aerial root growth.

Believe it or not, in addition to lowering temperatures, your air conditioner can also decrease humidity levels. This is because an air conditioning system uses refrigerant to absorb moisture and heat, ridding it from your home.

So, if you want a quick and easy way to take your humidity levels down a notch, switching on the air conditioner is a great way to do just that without investing in a costly dehumidifier.

3. Nutrient Deficiencies

If your cactus isn’t receiving enough nutrients from the soil, this can be another significant issue leading to root growth above the ground.

Aerial roots are a sign that your cactus isn’t getting the nutrients it needs to grow properly, so it tries to absorb those nutrients from the air around it. Again, while aerial roots aren’t necessarily a problem, they are a sign of an underlying issue that must be addressed.


There are various ways to increase your cactus’s nutrient intake and decrease the chances of aerial root growth.

The first and most effective way to do this is to use cactus fertilizer to ensure your plant is getting all the nutrients it needs to thrive. Many fertilizer options are available on the market, but your best bet is to stick to ones specifically designed for cacti.

Applying a slow-release granular fertilizer with an NPK ratio of 5-10-10 twice a year during the growing season (mid-spring and early summer) is usually enough to feed your potted cactus.

4. Need for Repotting

Another reason your cactus is sprouting aerial roots might be because it needs to be repotted.

If your cactus has grown a lot since it was placed in its current pot, its roots might now be cramped and not have enough space to grow, which can cause the appearance of aerial roots.

If you want additional information on how to tell if your cactus needs to be repotted, check out this article to read more: How to Know When You Should Repot Your Cactus


Repotting is a fragile but necessary process, so it’s important to go about it correctly.

The most essential part of the repotting process is choosing the right pot. Refraining from doing so can lead to drainage problems, which is another reason your cactus might grow aerial roots (more information later).

It’s vital to choose a pot with good drainage to avoid root rot or suffocation. Terracotta pots with drainage holes and trays are the best for cacti because the material is very porous, which helps your plant’s roots breathe easier.

5. Waterlogged Soil

If your cactus is getting too much water, this is yet another reason it might be experiencing the growth of aerial roots.

Aerial roots can absorb air from the air, essentially. If you notice your cactus growing aerial roots, this might mean that your plant is trying to absorb oxygen and carbon dioxide from the air, which it will try to do if it’s not getting enough from the roots growing beneath the soil.

If the soil moisture levels are too high, this can lead to root suffocation and the growth of aerial roots.


The best method for ensuring that your cactus doesn’t get overwatered is to check the soil before watering your plant.

To get a better grasp of how quickly the soil dries out, you can follow the steps below:

  1. Water your plant gradually but thoroughly until the excess drains out of the drainage holes.
  2. Record how many cups of water it took to saturate the soil. You can use the same number of cups every time you water your plant to avoid wasting water.
  3. Check how long it takes the soil to dry enough to warrant another watering.

For instance, if it took ten days, you can check the soil again after 7-9 days. This will ensure you’re not underwatering your cactus, especially on hot and dry days when the soil dries out more quickly.

6. Poor Soil Drainage

Another reason your cactus is growing aerial roots might be that it isn’t getting enough drainage.

As mentioned in one of the sections above, your cactus might grow aerial roots to ensure it gets enough oxygen. It usually does this if the soil contains too much water. While ensuring you don’t overwater is important, ensuring your cactus gets enough drainage is also vital.

If the water doesn’t drain completely from the soil after every watering session, this can lead to root suffocation, which causes not only aerial root growth but root rot as well.


One way to address drainage issues for your cactus is to make sure you’re using well-draining soil designed explicitly for cacti. Since cacti are native to dry, rocky environments, they need similar well-draining conditions in domestic settings as well, both indoors and outdoors.

Your cactus’s pot should also have enough drainage holes to facilitate soil drainage. 

If you think your cactus soil isn’t draining well enough, investing in some cacti-specific soil is a good idea.

Experts also recommend mixing your cactus soil with up to 50% pumice or perlite to promote better drainage conditions.

Final Thoughts

When your cactus is sprouting aerial roots, it could be a sign that it isn’t getting the care it needs. If your cactus is getting too much or too little water, is not accessing enough nutrients, needs to be repotted, or requires better drainage, it might grow aerial roots. This means that further steps should be taken to address these issues.

Hopefully, this article has helped you determine what might be causing your cactus to grow these roots. By following the provided tips, you can fix this problem and watch your cactus thrive.

Dr. Moritz Picot

Dr. Moritz Picot is a horticulture enthusiast and the founder of TheGrowingLeaf.com, where he serves as the lead content writer. He established the website in 2022 as a valuable resource for both gardening aficionados and beginners, compiling all the gardening tips he has accumulated over the past 25 years. Alex has a passion for nurturing plants, transforming backyards into inviting spaces, and sharing his knowledge with the world.

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