Cannabis Diseases Guide

Marijuana grown in indoor grow rooms are more vulnerable to diseases than those outside. if your marijuana are suffering from disease then its probably your fault! Most common are kinds of moulds and mildews which thrive in areas with high humidity, poor air circulation and over watering.


A fungus which loves wet and humid. It causes root rot, and rotting at the base of the stem (which turns brown). Very similar to “damping off” in seedlings, it affects mature plants. Spreads by spores in water, which makes it particularly virulent in hydroponic grows.  Avoid large fluctuations in temperature. Can be treated with chemicals, but has a nasty habit of reappearing if the right conditions continue. Fungicides are available, but as the root rot will stunt vegetative growth, probably the most effective treatment is to remove all infected plants as soon as possible, and once the marijuana grow has finished (or unfortunately died), carefully and systematically clean the whole area, tools and equipment using H202..


“Grey mould”, this can effect outdoor grows as well, particularly when temperatures fall to 15ºC in combination with drizzly rain over several days. Remove infected plants and dispose of well away from your growing area. Don’t do this whilst it is still wet or humid as this will provide conditions for new infections to spread to your healthy plants. In the grow room, make sure you have good ventilation and air circulation

 Tobacco Mosaic Virus

A virus which spreads mechanically from contact with contaminated material (soil, seed cases) to the plant. Causes distinctive mottling pattern on leaves. There is no cure apart from removal of the plant, all soil-based mediums and cleaning the area. Avoid cross contamination from other plants (tomatoes etc.) to your marijuana crop through good personal cleanliness!

Tips for avoiding cannabis diseases:

  • Foliar feed or mist only at the beginning of the “day” as excess moisture will evaporate rather than add to humidity levels
  • Keep air circulation fresh – keep a fan going
  •  Keep leaf matter out of the area – don’t allow any decaying matter in your grow room
  • Allow your marijuana plants to experience a drop in temperature at night
  • Check plants regularly so you can treat any problems early on.



[notify warn]




[notify textbox-white]

Marijuana Garden Saver: Handbook for Healthy Plants

Written by J.C:.Stitch and edited by the excellent Ed Rosenthal, this book is a godsend as a reference work. Its full of useful photos which is what you need when trying to diagnose what’s wrong with a sick or unhealthy plant.

Hopefully you won’t ever need it (although the fact that you are reading this post suggests you may do!) but when you do, its a great help.

Worth buying for its clear information ..  and because when you really need it, this book may save your garden




Leave a Reply

Your email address will not be published.