Marijuana Root Rot | How to Prevent and Get Rid of it?


Cannabis grower? Are you looking to cultivate a healthy marijuana plant? But wait, aren’t you already worrying about getting possible marijuana root rot? 

From seed to seedling, your cannabis plant is at risk of fungi and pest attacks. However, marijuana root rot is not as bad as it sounds. A few simple preventions here and there and some corrective measures can solve all your plant problems. 

Marijuana root rot

Make sure you follow our instructions to the dot. So, that you can have a fun experience growing cannabis and you can quickly get rid of any disgusting looking rot.

Fox Farm FX14049 Nutrient for Cannabis

Best Nutrients and Fertilizers to Grow Cannabis

Read more

What Causes Root Rot?

Gross and slimy rotting cannabis roots can be worrisome for any indoor or outdoor grower of the plant. But, what is causing this foul stench and nasty fungus growth on your precious marijuana plants in the first place? 

The answer is mostly a combination of various organisms, hiding in the soil or the water your plant is growing in. 

Let us explore in more detail what maybe some of the causes behind root rot in cannabis.


Your marijuana plant might not be getting enough oxygen. Sometimes the water in your reservoir lacks enough oxygen to give life to the plant. Other times, very high water levels can cause roots to start rotting too. 

So, your plant must have an optimum water level; otherwise, it will show signs of decay.

Warm Reservoirs

Warm reservoirs also facilitate the growth of harmful bacteria that attack plant roots, causing marijuana roots to rot. So, while some bacteria might be essential to plant growth, too much can cause a problem.

Light Leaks

Another common cause of rotting is light leaks. If your reservoir hasn’t been light proofed, then bacteria will multiply exponentially. You will be able to see this in the form of green algae around the root system.

So, if the roots of your cannabis plant have not been looking healthy, showing spots and turning yellow, now you know why. 

How to Detect Root Rot in Cannabis?

Marijuana root rot is every cannabis grower’s worst nightmare. Just thinking about it gives us chills. So, If you believe unwanted pathogens are partying in your hydroponic system. Here are a few symptoms that will help you confirm your hunch.

While each infection differs from another, they all cause once healthy roots to turn brown. So, if your cannabis plant is showing discoloration and brown spotting, that should be a red flag for you.

Rotting marijuana roots twist together. They start to look slimy and mushy like wet mud and have a very unpleasant odor that is impossible to miss. In some cases, the roots turn green as signs of algae growth start to show as well.

It is not only the roots of the cannabis plant that show signs of rot. If your marijuana plant is infected, you will notice changes like burnt edges or yellow and pale leaves appearing.

Root rot in the cannabis plant also means that the leaves of the plant will have abnormal growth. Old Leaves will begin to fall, and the remaining will either curl upwards or downwards in a strange fashion. 

Wilting or even drooping of the entire cannabis plant also starts to occur as the rot gets worse. You will also be able to notice weak stems and an overall frail-looking plant visibly.

So, if your marijuana plant has exhibited any of the symptoms above, then I am sorry folks, you’ve got root rot. 

So, you should take immediate action. Otherwise, your cannabis plant will soon perish.                                                                                                                                         

How to Get Rid of Marijuana Root Rot?

Marijuana root rot is a common problem for cannabis growers around the world, especially those who grow the plant indoors. 

While a root rot may look like the end of your cannabis plant that is far from the truth. However, you should not worry as you can still save your plant with a few simple steps.

Treat the Roots with Beneficial Bacteria

To prevent your cannabis plant from rotting, you should add beneficial bacteria to its roots. Since nutrient deficiencies are known to lead to rotting, therefore, for Hydro growers, there are several available formulas, like hydroguard that fights root ailments as well as prevents fungal growths, thus keeping your roots safe from rot.

Beneficial bacteria

The use of Hydroguard shows positive results in just two to three applications, so use this tried and tested trick. So, that you can get rid of root rot quickly.  

Add Some Oxygen

As we mentioned above, the lack of oxygen can have severe consequences for cannabis plants. Which is why, if you make use of air pumps to generate artificial bubbles, it will dissolve more oxygen in the water tank and provide the roots with an oxygen-rich environment to grow in.

Light Proof Your Reservoir

The organisms determined to cause harm to your cannabis plants love light and warmth. Which is why, it is crucial to make sure there are no leaks in your reservoir. And if there is one, you should cover your tanks with dark and thick tubs.

Doing the above will keep out both the light and the organisms that harm the plant, It helps you fight the root rot that is already in progress.

Use Hydrogen Peroxide Treatment

While this is not a long term cure for root rot, it is an effective way of treating the problem. An H2O2 solution, when added to water effortlessly, kills all pathogens and bacteria by temporarily seizing the rot. However, the peroxide solution converts into water and oxygen in one or two days.

Therefore, we recommend using H2O2 solutions to slow down rot while you figure out what is causing it. So, you can treat it accordingly.

Keep Your Reservoirs Cool

Water cannot hold dissolved oxygen at high temperatures, and as you already know, plants need oxygen to grow well. So we recommend that you maintain an ideal temperature of no more than 22 °C in your reservoir.

This will help you keep pathogens from multiplying and attacking your healthy cannabis roots and slow down the root rotting.

If you follow the measures we have just talked about, you will notice the rot going away. Your roots will turn back to their natural white color. Your once yellow leaves will show signs of color as they start to turn green again. 

For more information, read our article on how to fix a cold grow room?.

Why are my leaves turning yellow?

Why are my leaves turning yellow?

Read more

How to Prevent Root Rot in Cannabis?

Are you one of those lucky few who avoided having rotten cannabis roots and want to remain that way? Then, here are a few preventative measures you can take.

Watering Your Plants Properly

If you water your cannabis plant properly and make sure they get enough air, you will easily be able to prevent a possible root rotting.

Maintain Temperature and Humidity Level

When temperatures and humidity levels rise, insects like whiteflies begin to multiply and attack plants. Pest attacks like these cause cannabis roots to decay. However, you can prevent this by simply keeping plants in a temperature-controlled room where it is neither too hot nor too humid.

Keep Your Plant Environment Hygienic  

To avoid pests and diseases, remove the already dead part of the cannabis plant. Clean your trays and containers periodically, and remove lower branches to improve aeration.

Do Not Disturb the Roots

While changing tank water and cleaning it is a good thing, it can, at times, have an opposite effect. For the prevention of root rot, it is best not to change the water in the tank too often; especially, during the first 3-4 weeks of the plant’s life. 

Please wait for the plant to settle in and establish a colony of good and bad bacteria. Once you notice a grown biofilm around the roots, you can change the water in your tank more frequently. 

However, doing the same in the early stage of the plant’s life can offset the ph levels and cause deficiencies leading to root rot.

Use Root Boosters

Using a root booster allows for the healthy growth of the plant as well as its root system. Root booster is rich in vitamins, enzymes, organic and humic acids that keep the roots strong against any sort of pest attack.

By following these preventions, you won’t have the trouble of rotting roots at all.


Marijuana root rot is a common and persisting problem for growers of the plant. Root rot is the result of a pest or disease attack, or merely the wrong composition of nutrient solution in your hypodermic tanks.

If you don’t take quick corrective measures, the problem of root rot can get worse. However, even after your roots begin to rot, you can save the plant.

You can pump it with more oxygen or change heat and humidity levels. Changing environmental conditions slow down the reproduction of nasty bacteria that are out to harm your roots.

If you have avoided rotten roots, then you should still take caution and clean your tanks often and make use of root boosters.

Growing cannabis indoors can be a challenge, but if you keep following our instructions, you can easily prevent and cure problems of rotting roots. We hope these lines proved helpful.

Detect, Prevent & Fix Potassium Deficency in Cannabis

Read more

Receive our free book "Grow Your Own Weed Indoor"

Get The Ultimate Beginner's Guide for indoor cannabis cultivators. Start your journey to become the best indoor grower.