How to Spot, Treat and Prevent Cannabis Root Rot

What Does Cannabis Root Rot Look Like?

Cannabis root rot will often result in a noticeable color change in the precious roots of your plants, from pearly/milky white to yellow, brown, and slimy. When the roots are affected badly, they may even put off a smell of rotting vegetation!

You can easily detect root rot when utilizing hydroponics for weed growing.

However, if you're growing cannabis in a pot or container, diagnosing the issue can be challenging: it's difficult to even see the roots, and removing the plant from the container just risks root damage. But it's still better to take a look and try to find the cause of the issue, than stay in the dark!

Early signs of cannabis root rot often show on the leaves first, including curled leaf tips, brown or burnt spots, general yellowing, and even burnt leaf tips! If you see any of these signs, you should have a look at the roots to diagnose the issue!

Symptoms of Root Rot

Image via Grow Diaries

As previously mentioned, when the weed plant has root rot it will display symptoms in the leaves first! They will change color, droop, curl, and even display some signs of leaf scorch. If you check the roots and notice a foul of odd smell, it is most likely the start of root rot on cannabis!

Once root rot infects the plant, growth can slow down, or even stop completely. The roots of cannabis plants will slowly shut down, impeding the transportation of water and nutrients. If you leave it untreated, the plant's demise mighe be soon to come.

Main Causes of Cannabis Root Rot (Soil & Hydroponics)

Root rot is a type of anaerobic bacterial infection which attacks the roots, cuting off their essential functions. The infection appears when there are bacterias thriving in un-oxygenated environments. It's important to know that oxygen is crucial for proper root growth and functions including respiration, nutrient uptake, and transpiration. Oxygen also creates an aerobic setting which helps fight off bacteria, and aids in metabolism.

Growing in Soil (Pot/Container)

Several variables can lead to cannabis root rot. If you're growing weed in soil, root rot may be triggered by the following causes:

1. Soil texture: Some texture can lead to soil holding onto excess water and inhibiting proper oxygenation;

2. Poor drainage: It also leads to oversaturated soil, and ultimately depletes oxygen levels in the medium;

3. Temperature extremes: Excessive heat or cold impede root functions, and encourage bacteria to grow;

4. Overwatering: Too much water in the medium does not allow oxygenation of the root zone, so overwatered cannabis is quite susceptible to this ;

5. Pot/Container size: If the roots outgrow the container, they will not be able to stretch out and function properly, which will in turn slow down the nutrient uptake. That can cause the cnanabis plant to be susceptible to root rot.

Most of these factors keep the root zone from much needed oxygen, which sets up a perfect environment for cannabis root rot. The accompanying bacteria will kill healthy root cells, and even any beneficial bacteria which forms the root's sole defense mechanism.

Growing with Hydroponics

For cannabis grown in hydroponic system, the causes of root rot are very similar, but can vary a bit from those grown in containers (soil). Hydroponically grown weed plants are susceptible to root rot under the following conditions:

1. Poor water/reservoir conditions: When water temperature rises above 74°F (23°C) or drop below 68°F (20°C), it gets depleted of oxygen which roots need. Also, the water should be consistently oxygenated by airstone or other sources of oxygen, in case there's not sufficient oxygen supplied to the roots.

2. Tray or irrigation system: If the irrigation system or trays the plant lives on has had previous bacterial issues, it may be causing root rot.

3. Light leak: If light leaks into the reservoir, it can foster the growth of algae or bacteria, reduce oxygen levels, and increase the reservoir temperature. All these will contribute to the development of hydroponics root rot.

4. High level of EC/PPM: If the PPM/EC gets too high in the cannabis nutrient solutions, it can induce osmotic stress onto the plant and impair root function. It can also lower the water's capacity to retain oxygen.

Image via Hey abby grower_Leera

Image via Hey abby grower_DeeTownStars

Hey abby is a marijuana growing equipment with advanced hydroponic system packed inside. It not only includes in an airstone for a proper amount of oxygen, but monitors light and PPM/EC around the clock with its built-in sensors, which effectively minimize the risk of cannabis root rot.

How to Treat Root Rot on Cannabis Plants?

To fix cannabis root rot, it’s best to find the source that's causing the issue and fix that cause, rather than trying to chase and fix the symptoms. But, if one day you were to check on your roots, and see a brown, slimy, tangled mess, it’s best to take action immediately!

Using hydrogen peroxide with your water/nutrient solution is one way to get rid of root rot on cannabis. Adding roughly 5-10 ml of peroxide per gallon should help mitigate the issue. You will need to apply this solution to your plant during each water change, watering/feeding, or every 2-3 days for the best results!

There are also some microbial products which contain beneficial/microbial bacteria, which will outcompete the bacterial infection! Using these products can also stimulate the plants' immune response! All in all, look for products that contain beneficial/microbial bacteria, like Bacillus and Trichoderma — they will help prevent and get rid of root rot. These great tools prove useful for both organic and hydroponic growing!

Root Rot Prevention Cheat Sheet

It is best to act preventatively when it comes to cannabis/hydroponic root rot. FIrst of all, you should ensure that the water being used on the plant is within the right temperature range, no matter it's container or hydroponic growing!

If you’re growing in a container, you should make sure it has proper drainage, and aeration! I believe that cloth pots are the way to go; they allow plenty of runoff/leaching, and provide ample oxygen to the root zone! What's more, keep your medium aerated; using perlite or hydroton in your container will aid in proper aeration and allow for better runoff!

If growing hydroponically, you want to make sure that your water/nutrient solution has oxygen provided to it via an airstone or air pump, and that there is no light leakage into the reservoir! These are the best way to avoid getting root rot on your hydroponic weed plants!

Lastly, you'll want to start with premium cannabis seeds, since they often demonstrate better endurance when faced with adversities. Unsure of where to get good seeds or clones? Explore this reputable supplier, favored by numerous experienced Hey abby growers for its consistent quality and wide range of strain choices.

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