How To Fix Slimy Cannabis Roots?

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Added 12 January 2022

Root rot…ugh…the name is enough to send shivers down your spine if you’re a cannabis grower. 

Not only does it destroy the plants, but it takes a toll on your confidence as well. 

If you spot slimy roots, your plants are affected by root rot. 

Unfortunately, it’s one of the worst conditions to happen to your plant. But what is it, and how to fix it? 

This article teaches you how to identify and fix slimy roots, aka root rot. 

What is Root Rot in Cannabis?

root rot

Root rot or slimy roots is a condition that occurs if the roots are not in an optimal environment. Usually, improper environmental conditions make the roots stressed, shocked, or vulnerable to pests and pathogens.

When that happens, various organisms like bacteria, algae, and fungi attack the roots and turn the surface into brown slime — hence, slimy roots.

The brown slime stresses the root further. It keeps the roots from absorbing nutrients, oxygen, and water from the nutrient solution and growing medium. Eventually, it kills the plant.

Root rot is quite difficult to fix, but you can still save your precious cannabis plant if you act immediately. But first, let’s take a look at its symptoms and causes.

What are Root Rot Symptoms?

Cannabis plant struggling

Apart from brown slime, root rot exhibits itself in various other ways similar to nutrient deficiency. 

Here are some of the most common symptoms of root rot:

  • Burnt edges or tips of leaves
  • Yellow or brown spots on the leaves
  • Nutrient deficiency
  • Curled edges of the leaves
  • Stunted branch, leaf, or bud growth
  • Dropping or drying leaves
  • Less water consumption
  • Mushy stems
  • Soil and roots stinking

Difference Between Root Rot and Nutrient Deficiency

Root rot vs deficiency

As mentioned already, root rot exhibits symptoms similar to common deficiencies. For instance, the leaves may turn darker or lighter, which you could confuse with nitrogen deficiency. Or, deformed leaves may look like a copper deficiency. 

However, some key differences help you differentiate one from the other. 

  • The plants are slow and take an inordinately long time to develop stronger stems and leaves. In addition, the leaves don’t grow as big as they should.
  • The stems may become mushy, especially after you’ve watered them. 
  • Over time, the stems may exude a rotting smell.
  • The soil will also stink.
  • The roots also display problems and change their color. Typically, healthy roots are white, whereas those affected with root rot will become brown. 

What Causes Root Rot in Cannabis?

Root rot causes

Knowing the cause of root rot is essential to fixing it; otherwise, it will be back to affect your plant’s health. Here are some of the causes of root rot in cannabis plants:

  • Excessive heat: Due to the warmer environment, roots grow a tendency to grow fungi and bacteria on their surface
  • Excessive cold: Too cold an environment causes unhappy roots, aka shock, resulting in root rot
  • Overwatering: Overwatering drowns the roots, and the moist environment attracts all kinds of harmful microorganisms that reproduce quickly, turning into root rot
  • Dense medium: Similarly, a thick medium starves the roots of oxygen, making them a habitable place for harmful organisms 
  • Improper hydroponic setup: This can cause various issues listed above, like lack of oxygen, heat, or drowning, resulting in algae and bacteria growth on the roots.

How to Prevent Root Rot?

Root rot prevention

As always, prevention is better than cure. Since root rot is extremely difficult to treat, it's best to prevent and protect the plants from getting affected.

Here's how to prevent root rot in your cannabis plants:

  1. First, always start with a good substrate before growing cannabis plants. Whether you purchase it online or at local stores, go for high-quality substrates that encourage your plants to grow well.
  2. Soil can become hard at times, so always use high-quality soil that encourages aeration. You can also mix in perlite and other additives to create aerated soil. Low-quality soil can clog up the roots of the plants, so purchase soil only from verified sources.
  3. Overwatering kills the plants a lot faster than under-watering. In addition, overwatering is one of the primary causes of root rot. Cannabis plants grow well if you have a fixed schedule to water them. Therefore, always maintain a schedule and avoid overwatering at all costs. In addition, make sure you water the plants only when the soil is dry. You can lift the pot to check its weight and water only when it's light, or you can insert your finger into the soil to figure out if it's wet or dry.
  4. Root rot is often caused by pathogens, including fungi. Thus, maintain a clean environment that deters fungi and mold. For instance, check the soil for fungi before sowing seeds. 
  5. It's essential to take care of the roots to prevent root rot. In addition, applying root boosters frequently will help the plants develop healthier roots.
  6. Lack of ventilation coupled with overwatering encourages root rot, so use extra fans to dry off excess water and increase ventilation. In addition, high humidity levels affect the roots, so maintain a suitable environment around the plants to prevent root rot.

How to Treat Root Rot in Cannabis?

Time is of the essence when treating root rot. If you wait too long, treating it would be impossible. So, get started as soon as you spot brown slime on the roots. 

Here’s how you can do that.

So, start by checking the environmental factors of your culture, like humidity, temperature, watering frequency, and drainage of the medium. Here is a brief shortlist of some factors you should especially focus on:

1. The reservoir, root region, and hoses should be completely light-tight. If growing in soil, make sure you're using clean soil before planting the seeds. 

2. The humidity should be:

Seedling stage: 65% to 70% 

Vegetative stage: 40% to 70%

Flowering stage: 35% to 40% 

Late flowering stage: around 30% 

3. The temperatures should be:

Seedling stage: 20°C to 28°C or 68°F to 82.4°F

Vegetative stage: 20°C to 28°C or 68°F to 82.4°F

Flowering stage: around 23°C

Late flowering stage: 18°C to 24°C

4. Ensure the pH and NPK levels of your nutrient solution are ideal for your particular growing system

5. The growing medium should not hold too much water or be too dry 

6. If you notice any of the environmental factors to be off, rectify them immediately. We recommend participating in our forums to discuss the optimal environmental factors for your specific setup and region. 

Ensuring your cannabis setup is proper is just a long-term solution, but you still have to combat root rot in your cannabis plants. Follow these steps to reverse the damage of root rot.

Treating the plant

  1. Remove the affected plant from the medium
  2. Rinse the slimy roots under running water to remove as much slime as possible
  3. Trim any damaged root parts with disinfected scissors 
  4. Dip the roots in 3% hydrogen peroxide solution for a few seconds
  5. Place the plant in a shallow tray for a few hours to dry 

Cleaning the growing environment

  1. Discard all the nutrient solution
  2. Soak the entire system, including pumps, hoses, and other components, with a 10% bleach solution for a few hours
  3. Then, rinse the system with a fresh nutrient solution 

Replanting your cannabis

  1. Add beneficial bacteria and nutrients to the growing medium to help your roots recover; you can use products like Hydroguard, Piranha, Voodoo Juice, or Rooters
  2. Use air stones to increase oxygen levels in the nutrient solution
  3. Lower the grow medium and reservoir’s temperature
  4. Replant the plant and give it some time to recover

Follow these steps and let your plant heal. We recommend keeping a close eye on your grow system for the first couple of weeks to ensure the roots don’t develop slime again.

Many growers also choose to completely discard the plant and start again. If you plan to do so, know the cause of root rot first and check your grow system meticulously before replanting.

Summary: How to Fix Slimy Cannabis Roots?

Root rot or slimy roots on cannabis is a serious condition that is difficult to reverse but is relatively easy to prevent, too. All you have to do is provide an optimal environment for your cannabis plants to grow. 

Apart from that, follow these tips:

  • Never disturb the roots or let light get to it
  • Change the reservoir solution at least once a week
  • Never let your plant sit in stagnant water 
  • Avoid warm reservoirs; invest in air conditioners and humidifiers
  • Eliminate any light leaks from the reservoir, hoses, or the root region
  • Maintain optimum oxygen levels in the nutrient solution
  • Do not overwater your cannabis plant
  • Remove any decaying or dead matter immediately

Root rot is something you need to worry about, but if you follow the steps listed above, you can still recover your plant easily. All we ask you to do is act immediately and not panic. 

Figure out the cause first, check for any issues in the system, rinse the roots to remove the slime, flush the grow medium and reservoir as suggested, and introduce the right supplements and environment to the system to replant.


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