What does bud rot look like? 3 phases explained

When growing cannabis, there are multiple pests that could cross your path and try to ruin your plants. A very common type of pest are the multiple types of fungus/mold. These will grow and eventually take over your plant to destroy it. The most common type of mold that cannabis growers experience is called “bud rot”.

Bud rot is a type of mold that only shows up in the flowering phase of a plant. It starts to grow in the inside of a bud, slowly taking it over untill it’s visible on the outside (At this time, infected buds will be ruined). Bud rot is very contagious and will spread very quickly, so it’s important to treat this pest quick and effective.

Fungus/mold only survives in specific environments. So to treat them, you simply need to change the circumstances of the growroom/area. Bud rot needs 3 things to survive and spread:

  • wet/moist circumstances
  • No/low air circulation
  • Cold temperatures (Under 20°C/68°F)

The main rule to treat/avoid a bud-rot infection is recognizing it on time.

But what does bud rot look like?

Bud rot shows up in different phases as it takes over a plant. It’s very important to recognize the first phase, at this level you are still able to save most of the bud. However like I said, it spreads pretty quickly so the next phase will show it signs soon!

Different phases of bud-rot:

In the beginning, it’s sometimes very hard to recognize a bud rot infection. It’s starts from the inside of the bud so without a good inspection, it’s not visible. Our first tip is to keep a very close look on your plants, daily! If you missed the first signs, it will

First Phase:

Even if the bud rot starts inside, there are 2 signs you could recognize pretty easy once your plant is infected:

  • The first sign is a white, fluffy, fungus-like material appearing on certain spots around the buds. This material is very fragile so be carefull: It could contain spores leading to new growth of bud-rot if handled
  • The second sign is that bud-leafs (smaller leafs that grow in between/out of a bud) are starting to get brown and dried out/curl up. If you see this, immediatly check out the inside of those buds!
Brown “bud-leafs” and white fluff appearing on spot around the buds

Once you spotted one of these signs, it’s time to take action! At this time you can save most of the buds by changing the environment, and carefully cut away the infected spots.

Second Phase

If you didn’t recognize the first signs and you leave your plants in the same circumstances, it’s a matter of days/weeks that the bud rot spreads around and take over your buds. In the second phase, it’s easier to recognize the signs. However, more parts of the bud(s) are infected and have rotten away now.

Slowly, the signs are getting visible. The first visible calyces are turning brownish/grey and more bud-leafs are getting darker and dry out. On some spots you will see brown/grey mushy spots appearing (where the rot is coming out). You might also see the first spores appeare as black small spots that releases easily. (these can infect other parts of the plant/other plants)

In this phase, you still can safe some of the buds if you act on time. Make sure to cut away all infected buds and change the growroom circumstances immediately.

The bud rot is slowly getting visible from the outside. In this phase it’s easy to recognize it but you need to act quickly to safe some your buds.

Third phase

If you don’t do anything about, it takes just some days for the bud-rot to take over most of your buds. Spores already infected other buds/plants and there is nothing you can do to reverse the process. Everyday you will see more of your plant material turning to fragile, grey mushy stuff. Eventually leaving you with nothing bud brown, rotten buds. They break down easily so make sure to avoid breathing in small particles.

If you let it get this far, there is only one thing to do: Accept your loss and try another grow after you changed the environmentel circumstances of your grow area. Smoking infected buds is very bad and could cause health issues. Also make sure to clean your growroom very good before starting a new grow (Spores of the fungus will still be around).

On this plant, you can see that the bud rot has taken over a complete nug and even the stem is affected. This happens if you dont change the circumstances and cut it away on time.
Even once your plant is harvested, bud rot is able to grow and spread around a bud If the circumstances are still wet and cold. So make sure you have a suitable place to dry your cannabis.

Do you have any tips to recognize or treat but rot yourself? Make sure to leave them in the comments below!

Find out more about bud rot and how to treat it in our “ultimate pest guide”

2 thoughts on “What does bud rot look like? 3 phases explained

  • August 23, 2021 at 7:44 pm

    I remove contaminated areas with scissors and and have a spray bottle with alcohol in it and clean the scissors after every single cut. After I have cleaned up the plant, I use a spray bottle with 50/50 alcohol and water and spray the plant down in the evening after the sun sets. Both sides of leaves. This also works on powdery mildew. Make sure that you do not touch any other plants with your clothing, hair or anything. Take off your clothes and put in the washing machine and take a shower after working with the plant. DO NOT touch any other plants. Make sure your scissors are soaked in the alcohol and cleansed thoroughly.

    • August 23, 2021 at 11:12 pm

      Great tips and you are absolutely right. Bud rot is a fungus and it’s spores are very easily to carry around and infect other plants with it. Working extremely clean is the key here! 🙂


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