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How to Maintain Hydroponic Roots to Avoid Root Rot?

Created by
Added 07 September 2022

Root problems are very common if you’re growing cannabis hydroponically, so how do you maintain hydroponic roots to avoid root rot?

If you are growing your cannabis hydroponically, you have a terrific advantage — your setup encourages your plant to grow vigorously and reap a better yield. However, there is one major problem with hydroponic setups — they are less forgiving.

If you make a mistake, the problems start appearing quickly and more frequently. And one such problem is root rot — a common issue that infects many cannabis plants. 

But, thankfully, this problem is easy to avoid in the first place by simply maintaining the roots. And here is a short guide on the same.

What is Root Rot

Root rot in DWC

Image Credit - Fastbudsfanatic

Root rot, or slimy roots, is a common problem that occurs in roots but affects the entire plant. The fungus starts growing on the roots' surface, preventing them from absorbing the nutrients properly, causing various deficiencies in the plant, and eventually the plant's death.

Root rot develops on the roots, turning the roots creamy white or brown with a slimy film over them. Another notable sign of root rot is the roots smelling earthy even though hydro roots generally don’t smell like it. 

This is where the problem begins, but it goes on a lot farther. Soon enough, the roots stop absorbing nutrients and the plant develops symptoms like uneven or stunted growth, nutrient deficiencies, withering leaves, reduced root mass, damping off of seedlings, and a lot more. 

If not treated on time, root rot will kill a plant. So, how do you avoid root rot in cannabis plants? Well, first we find out why and what causes it. 

Causes of Root Rot

Root rot most commonly occurs due to the fungi species of Phytophthora and Pythium, which are water-borne fungi that thrive in damp environments with low oxygen levels, like in many hydroponic setups. 

These fungi spores make way to your roots in various ways, such as the following:

  • Pests like fungus gnats can carry the spores to your plant
  • If you transplant plants already infected with the disease, the spores can quickly spread to other plants
  • Use of infected tools or equipment 
  • Overwatering, where the moist environment further encourages fungi development 
  • An improper hydroponic system with a lack of oxygen or high temperature and humidity levels, which can increase bacterial growth on the roots

Easy Ways to Avoid Root Rot in Hydroponics 

root rot in hydroponics

With some basic adjustments and gardening techniques, you can protect your hydroponic plant from root rot easily. Follow these tips.

1. Control the Temperature and Relative Humidity

One of the most common causes of root rot in hydroponic plants is high temperature and relative humidity. So, ensure you keep these in check. This problem is common in hot and humid climates where the water temperature can rise above 65°F or 18°C. 

Since the water temperature is generally 10 degrees lower than the room temperature, try to maintain your grow room’s temperature under 75°F or 24°C. This will keep the water cool enough to prevent fungal growth. 

For humidity in the grow room, it should be:

  • 65% to 70% during the seedling stage
  • 40% to 70% during the vegetative stage
  • 35% to 40% during bloom
  • 30% during late-bloom

If the temperature or relative humidity is not ideal, you can use devices like air conditioners, vents, dehumidifiers, etc. to bring them to the ideal levels to avoid root rot in DWC.

2. Keep the Grow Room Sterile 

Next, ensure that the grow room is clean and sterile. Pathogens can travel to your indoor grow room via contaminated tools, grow on dead plant materials, or get in through vents. Therefore, you need to regularly clean the grow room of any dust and debris and keep the tools you use sterile. 

One of the best ways to ensure your tools and equipment stay clean is using isopropyl alcohol to wipe them after every use and keeping them in a dry, dark place in the grow room. 

Also, avoid wearing the same clothes in the grow room that you wear outside. You never know which pathogen or pest may hitch a ride on your clothes.

3. Use Biogungicides

Like you use friendly pests to ward off harmful pests, you can also use friendly bacteria to ward off pathogens. Essentially, bio-fungicides are cultures of bacteria that can kill and ward off pathogens responsible for root rot (and various other health problems).

You can buy them at your local horticultural store and they are quite easy to use. All you need to do is mix them in water and apply them to the target area. But do read the instruction label to know more about the usage. 

An added benefit of this is that they encourage healthier root growth with improved oxygen absorption capabilities. 

4. Keep the Roots Dark

Another common reason for root rot is light in the root zone, which can encourage fungal growth. So, you need to ensure that the root zone of your hydroponic system is completely dark at all times. Even a small light leak can lead to fungal growth and root rot. 

To make the root zone free of any light leaks, use things like dark tape, black pipes, and light-proof pots. You should also consider keeping the reservoir completely dark to prevent fungal growth in the solution. 

5. Ensure High Aeration Levels

Next, you need to ensure that the water solution is well aerated since fungi tend to grow more in oxygen-deprived root zones. Aerating the nutrient solution will boost oxygen levels in the root zone, preventing fungal development.

One of the easiest ways of aerating your nutrient solution is to use air stones. They are cheap to buy and have excellent aeration capabilities. Just place one in the reservoir and let it aerate the solution throughout the day.

6. Water the Plant at the Right Time

Fungus or root rot also occurs in damp root zones, which is due to overwatering. So, you need to ensure you are not damping off the root zone by watering it too much. 

Depending on your hydroponic setup, learn more about the particular watering techniques and apply them to ensure you only administer enough water, not more, not less.

7. Change the Water Regularly

Additionally, you also need to keep the reservoir full of fresh water. Stagnant water is another common habitable zone for fungi, which can develop into root rot.

As a general rule of thumb, you should replace the reservoir water once you have refilled it equal to the reservoir’s total capacity. For example, if your reservoir tank is 20 liters, and you have already topped off the reservoir with 20 liters of solution, it's time for a fresh solution altogether.

But if you don’t want that hassle, change the water once every week to keep it fresh. 

8. Prevent Pests

Lastly, prevent pests from coming into your indoor grow room at all costs as they can carry various harmful bacteria and fungi with them. Plus, pests are a nuisance and even if they don’t carry spores, they can still harm your plant in various ways. So, it’s best to avoid pests. 

How to Treat Root Rot in Cannabis Plants?

Root rot in cannabis

Image Credit - Jaygrow1020_autoking

Despite taking all the measures mentioned above, your plant can still experience root rot in some cases. If you happen to notice root rot on your plant, you need to act quickly. Follow the steps mentioned below to treat root rot in your plant.

1. Treat the Plant

The first step is to treat the plant itself. For this, follow these steps:

  1. Remove the plant from the medium 
  2. Rinse the roots under clean running water to remove slime 
  3. Cut off any damaged parts of the roots with sterile scissors
  4. Then, submerge the roots in 3% hydrogen peroxide to water solution for a few seconds. 3% solution equates to 3ml hydrogen peroxide per 100 ml of water. 
  5. Lastly, place them in a tray for a couple of hours to dry out.
  6. You can also use products meant to treat root rot, such as Hydroguard to clean the roots. To prevent root rot, use it with every watering. 

2. Rinse the Hydroponic System

Once the roots are treated, you then have to clean the hydroponic system off any fungal residues and spores. For this, follow these steps:

  1. Discard the nutrient solution no matter how fresh it is
  2. Bleed the entire hydroponic system with 10% bleach solution to water. This means that you should mix 10 grams of bleach per 100 ml of water. 
  3. Use a fresh nutrient solution for a final rinse 

3. Replant Your Cannabis

Now, your plant and hydroponic system are completely clean and safe for the plant. So, follow these steps:

  1. Add beneficial nutrients and bacteria to the medium to keep your roots healing properly. Use products like Piranha, VooDoo Juice, Hydroguard, and Rooters
  2. Check the tips listed above for root rot prevention, especially the reservoir oxygen levels and temperature of the grow room
  3. Replant your plant and let it recover 

Summary: How to Maintain Hydroponic Roots to Avoid Root Rot?

Root rot can be subtle at first, but it is quick to kill your plant. Not only that, but unhealthy roots can also lead to other problems in the plant like stunted growth, nutrient deficiencies, wilting, and some more. 

This is why you must maintain the roots of your hydroponic plant. Even small mistakes here and there can cascade into major problems, and many of these problems can be avoided with healthy root growth. 

So, root for your root’s health and take the right measures. You will reap what you sow as long as the roots are healthy. 


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