Root rot is a phenomenon that often occurs when the temperature of your reservoir water is too high, as it expedites the growth of bad bacteria. Check out photos and more information on root rot below. 


What is root rot & how did I get it?

Root rot occurs when the temperature of the water in your reservoir is too hot.

Cannabis root rot can be caused by different pathogens, a solution that solves the symptoms of root rot for one grower may not necessarily work for another. That being said, there are tools to fight against root rot no matter what kind you have!

Grobo recommends keeping your unit in a temperature-controlled environment to avoid your water reaching too hot of temperatures. Grab a water chiller if you are thinking your water is too warm! Check out THIS one that Grobo offers. 


What does root rot look, smell, and feel like?

  • Roots with root rot will look mushy, slimy, and like they’re covered in snot or goo substance
  • The root system will smell like decay
  • Often you'll notice first a change in the plant's foliage. Leaves begin to wilt and turn yellow, growth will slow, and blooming may be delayed


Image 1: Beginning of root rot


Image 2: Advanced root rot


Image 3: Severely advanced root rot



Nutrient-stained roots can sometimes look like root rot.

Healthy roots with staining will show:

  • Evenly stained, all the same colour
  • No sign of stress on your plant. You shouldn't see wilting or other root rot symptoms

The key items you are looking for to determine if it is root rot are slime and a foul smell. 


Image 3: Healthy, stained roots


Think you have root rot? Here are your next steps!

Feel free to reach out to us at if you aren't sure! We are happy to help. 

In order to get rid of root rot successfully we will need to address both the environmental conditions your Grobo is in and the water temperature your roots are in. We will start by removing some of those slime-filled roots.

  1. Take out your reservoir lid with the plant still inside
  2. With clean hands, very gently pull on your roots to remove any roots that are soft/brown/slimy
  3. Discard what you have pulled off 

Long Term & Short Term Solutions: 

  1. Long-term Solution: Reduce the temperature of the room your Grobo is into 75F or under. Pump that air conditioner or move your unit to a cooler area (don't forget to drain it first!). Lower temperatures will help kill off root rot.
  2. Long-term Solution: Thoroughly clean your tank in between grows (How do I clean my Grobo?). Soak the tips of your dosing tubes and scrub your air stone with a toothbrush.
  3. Short-term Solution: Add Hydroguard to your reservoir (see HERE) when your plant is in Stage 1 (Germination). The instructions on how much to add are on this product's packaging. Stop using this during the flush stage.
  4. Short-term option: Put a cap-full of hydrogen peroxide into the water every time you drain and fill the tank. This cannot be conducted through an entire grow. We recommend only doing it 3 times.
  5. Short-term option: To cool the water in your reservoir, you can add a frozen bag of water to it each day. Keep two in your freezer and 2 in your water tank, and swap them out each morning. 
  6. Check out THIS post on AllGrowers. @Vegetato's comment on November 22nd provides a very detailed overview of how they personally used hydrogen peroxide to deep clean their roots. If your roots are saturated with root rot, we recommend this tactic.
  7. Use a water chiller to reduce the water temperature in your Grobo. Check out THIS one that Grobo offers. 



For a detailed discussion about root rot and how to solve it in a hydroponic setup, check out our blog HERE.