Root rot is a phenomenon that can occur when a Grobo has not been effectively cleaned in between grows, or, the temperature of a Grobo's reservoir water is too high, which expedites the growth of bad bacteria. As the bacteria advances, healthy portions of root turn brown and mushy. If left untreated, the plant's growth will slow and it will eventually die.
Identifying Root Rot
Root rot can be identified by the presence of slimey, dark brown roots (Figure 1). The root system of a healthy plant should be firm and white. But if root rot is present, the plant will be unable to absorb the nutrients and water it needs as it's taken over by bacteria. This deficiency eventually becomes apparent in the plant's foliage. Leaves begin to wilt and turn yellow, growth slows, and blooming may be delayed. The root system will also smell like decay, which is exactly what's happening. These symptoms are similar to an underwatered plant, as the foliage here is also unable to receive its needed nutrients and water.
Fig 1. Here is a plant with a large amount of root rot.
Dealing with Root Rot
First, take out your reservoir lid with the plant still inside and, with washed hands, VERY gently pull to remove any film and any soft/brown/slimy roots from your plant. Then, discard them afterwards.
Next, conduct the following mitigation and prevention tactics.
- Try to reduce the temperature of the room your Grobo is in, or, drain it completely and move it to a colder location. This will help slow down the development of bad bacteria.
- To cool your reservoir, you can add a frozen Ziploc baggie of water to it each day. Keep two running in and out of your freezer, and swap them out each morning.
- Put a cap-full of hydrogen peroxide into the water every time you drain and fill the tank. This is a short term solution only, however, and cannot be conducted your entire grow. We recommend only doing it 3 times.
We also would like to highlight THIS post on AllGrowers where a user tackled a root rot event. Please see @vegetato's comment on November 22nd, 2020 for a very thorough overview of how they use hydrogen peroxide to deep clean their roots. If your roots are completely saturated with root rot, we recommend conducting this tactic.
Preventing Root Rot
There are two actions you can conduct to help prevent the development of root rot:
- Thoroughly clean your tank in between grows (see HERE). Soak the tips of your dosing tubes and scrub your airstone with a toothbrush.
- Begin adding Hydroguard to your reservoir (see HERE) when your plant is in Stage 1 (Germination). This product is a beneficial bacterium that increases the size and density of the roots' mass, we well as nutrient uptake. Adding it early on will help good bacteria build up a protective barrier on your roots. The instructions on how much to add are on this product's packaging, but we recommend reducing it by 1/4 when using this product in a Grobo.
Still have questions? Please see HERE for how to contact us.