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burned roots seeding cannabis

Early indications of nutrient build-up prior to burning can be:

Prevention is always the best policy, so it is a bright idea to develop good habits that decrease the chances of mistakes. First of all, be sure to use the correct nutrients for the appropriate growth stage. Even then, it is a wise idea to only use ¾ the recommended dosage on product packaging. Sometimes, manufacturer recommendations can run things a bit “hot,” which leaves little room for error.


Nitrogen is the predominant compound found in cannabis nutrients, especially during the vegetative phase. Nitrogen toxicity will be quickly followed by more severe symptoms.

Further indications of nutrient burn are yellow, burnt tips on leaves. This will be widespread as over-fertilisation affects the whole plant. Small, burnt tips are common and nothing to worry about. When the yellowing intensifies and advances, however, it is time to take action. Once leaves start to curl and go brown, they are definitely goners.


Step 1: Identify what may have caused the root problem (refer to list of possible triggers above)

The cannabis plant below did not have any drainage holes (water could not drain out the bottom of the pot). Notice the strange twisting of some of the leaves. When roots are left in stagnant water for too long, they cannt get enough oxygen and tend to develop root problems.

This clone was give the same amount of water from when it first sprouted. As the plant started getting bigger and drinking more, this wasn’t enough and became chronically underwatered (a different type of root problem, with similar symptoms). What this particular plant needed was to be given more water at a time. One warning flag was that the plant was drying out every day (you should only have to water your plant every few days, if it’s drying out in just one it likely needs more water at a time). It’s always a good idea to listen to your plants when deciding when to water, as opposed to following a set schedule. Each plant and environment is different, and what works for some plants may not work as well for others!

Plant Symptoms

More overwatered marijuana seedlings – these were overwatered since theyf first germinated. If leaves are drooping down in normal heat, but still seem kind of “fat” it’s often something with watering or roots!

This particular type of cupping of the leaves below is common among cannabis plants with root problems. In this case, the plant had no drainage from the bottom of the solo cup, so water was just pooling at the bottom for the roots to sit in. Once the grower poked holes in the bottom of the cup, this problems went away (the cupped leaves didn’t recover, but new leaves started growing in happy and healthy).

Chronic overwatering in thick soil led to these symptoms. The main thing that alerts you to the fact that the yellowing is caused by overwatering is the fact that it’s droopy. It’s very easy to overwater young plants when you have a small seedling in a big container. When that’s the case, don’t soak the whole growing medium. Water in just a circle around the plant until its leaves are up and growing fast. At that point you can start watering more thoroughly 🙂

You May Not Want to Use Hydrogen Peroxide (H2O2) for Root Problems! H2O2 is temporarily effective at best when it comes to root problems. By it’s nature, even commercial grade H2O2 will be completely gone from a water reservoir after about 24 hours as it reacts with the water to form oxygen (decomposes) until the H2O2 is completely gone.