How To Identify And Prevent Bud Rot On Marijuana Plants

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How To Identify And Prevent Bud Rot On Marijuana Plants

By Robert Bergman, ILoveGrowingMarijuana.Com

Bud rot is the worst nightmare for marijuana growers. It’s hard to prevent or identify and it will ruin your whole cannabis crop. Bud rot develops on the inside of the buds and spreads very quickbudrot. Even when your marijuana is drying, this mold will stay active so make sure you’re well prepared for this nasty fungus.

1. Prevention is better than cure

Bud rot, also known as botrytis cinerea or grey mold, thrives best when air is very humid and temperatures are low. It develops in the last phase of the flowering period, when air humidity should be between 30% and 40%. The problem is that humidity will increase as you water your marijuana plants. This is why you have to make sure not to give plants too much water and prevent excess spilling. If you water your plants from underneath, make sure you dose the amount so that it takes no longer than one hour for the plants to absorb all of the water. Also, water your plants when the lights have just turned on. Temperatures are then higher and water will damp or be absorbed quicker than when lights are out and your marijuana plants are ‘sleeping’.  In addition, make sure the space is very well ventilated and excess air is extracted. Fans must blow air between the buds and lamps, preferably an oscillating fan.

When growing marijuana outdoors, place your plants in sunlight and in an area where wind creates enough ventilation. Morning dew can then damp quickly evaporate or you can help get rid of dew by gently shaking it off. The best case would be to place your marijuana plants indoors at night so that cold air and damp won’t harm them too much. By placing plants slightly higher than the ground for better ground temperatures, you help your plant’s resilience against diseases. You can also treat your marijuana plant with Teldor from Bayer. But only use this on the stem during flowering phase so the wax coating does not rinse off easily.

Delta Extrax

2. Recognizing marijuana bud rot

Keep an extra close eye on your marijuana plants during the last weeks of the flowering period. Always look for diseases and abnormalities, but especially for bud rot. You’ve come too far to see a good cannabis crop go to waste after all the hours you’ve spent cultivating your plants. You can recognize bud rot by inspecting the small one finger leaves growing from the buds. If these are green, you’re in the clear. If these have a yellow or brown color, chances are you have bud rot. These leaves let go easily when removed and do not look healthy. If you see this kind of leaf, remove it immediately and bend open the top carefully and look inside and see if things are looking OK.

3. Intervention

Once you’ve identified bud rot on your plants, you need to act quickly. It might be hard on you, but you have to remove any and all infested buds. Bud rot spreads very quickly and it will ruin your entire crop. Use disinfected scissors to cut out rotting buds. Also be very careful not to touch healthy buds with your infected hands. Check every day for bud rot and cut out infected buds immediately!

Want to know more about growing marijuana? Check out the FREE book Marijuana Plant Care for more information!


  • Pete
    June 3, 2014

    Yes, probably the growers worst nightmare. Here is a solution.
    I do not know if they ship but available in Victoria B.C.
    We have used it for 2 complete rotations now and absolutely delighted!

  • Donna krunnies
    August 17, 2014

    So… Just discovered bud rot in crop just days away from harvest. Can I harvest buds not showing sign of rot and save them or will it all be lost. Read that it is harmful to smoke. How about uninfected buds ? Are they risky too? Help and thanks

  • Donna krunnies
    August 24, 2014

    Hello… I ask the above question but no answer yet??? Is this not going to be answered? Or am I just not finding??

    • kushie
      September 2, 2014

      Just salvage one thats not molded and toss that molded one they are no good will get you sick mostly main colas will have mold its a grower worst nightmare it take 50% or more of your crop easily. i tend to harvest once i notice so I can save what not molded.

  • bdiggity
    April 7, 2017

    hey there does anyone know if bud sometimes might have a moldy smell as this is my first grow i been smelling a mildewy smell off and on for three days bud my plants look super healthy and im freaking out lol.

  • ralph
    October 18, 2017

    had 3 big 6,7 ft tall plants growing outside.
    everything looked good until the end of sept,
    lots of big colas,buds developing,but i was finding
    some rotton buds,around 6.7.10.or more some days.
    mostly on one plant?the most northern one.
    i decided to let them grow a bit more,to the 10th of oct,
    big mistake///.i cut them down on the 10th,and hung them up under my barn.
    they had lots of air blowing through them,but it was cold,freezing
    a couple of nites,anyway.when i started to pick of the fan leaves
    every bud on every cola.and every top,was rotton.
    i ended up with a lb,of the poorest quality little buds,and i threw away
    about 2 lbs,or more.of the biggest,and best buds.never seen anything
    spread so fast.needless to say,my heart is broken.

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