What to Do if Your Outdoor Plants Get Infected With Mold

What to Do if Your Outdoor Plants Get Infected With Mold

As we creep closer to Autumn, it will not be long now until your outdoor plants will be close to harvest! It may feel like a lifetime since you first planted your seedlings in April; however, all your hard work, dedication, and tender loving care are about to pay off. 

One potential problem that an outdoor grower can face is bud rot (botrytis). In this article, I will explain what causes mold, signs to look out for, what to do with moldy buds, and frequently asked questions to help you stay fungi-free in 2025.

What Is Cannabis Mold and What Causes It?

We have all been there when you notice that your biggest and fattest buds appear to have a grey or light brown color, and under close inspection have a spider web characteristic. When touching the buds, you may notice they have become soft and mushy, feeling like they are about to tear open like candy floss. 

Unfortunately, this is a prime example of a moldy cannabis bud. Botrytis and mildew can appear out of nowhere and spread through your buds in no time, leaving growers feeling panicked and feeling like they are about to lose their entire crop. 

Mold is a type of harmful fungus that attacks organic matter when the conditions are damp and moist. As we draw closer to the end of Summer, the nighttime temperature will begin to drop, and depending on where you live, rainfall may be common. 

• Dense buds with poor airflow are common targets for mold.
• High humidity levels around the buds will cause mold.
• Hot and cold temperature fluctuations can promote mold.
• Humidity levels exceeding 60% will cause buds to mold.
• Rainfall can cause buds to become wet and start to mold.

How to Know if Your Buds Have Mold

Suppose it is your first experience growing cannabis outdoors. In that case, you will most likely not be familiar with mold and how much damage this harmful fungus can do. Mold can set in on the outside of your buds, and in a worst-case scenario, will cause the buds to rot from the inside out, resulting in a devastating loss. Below is a list of all of the signs and symptoms to look out for when inspecting your buds during their final weeks of flowering outdoors.

• The buds will have a brown or yellow coloration.
• The structure and texture will become soft and mushy.
• Inside the buds will be dark grey calyx that smell like fungi.
• There will be an earthy and musky aroma.
• The buds will easily tear apart when handling them.
• Small black and grey spots will appear on the outside.
• The surrounding leaves often have signs of powdery mildew.
• A white spider web texture will grow on the outer buds.

What to Do With Cannabis Buds That Have Mold

Apart from carefully removing them from the plant to avoid the fungus spreading further, there is nothing you can do. Once mold spreads, it is a matter of preventing it from happening again and attacking the other buds on your outdoor plants. Below is a list of preventative measures that can be taken.

• Improve the air flow around the canopy and buds.
• Build a rain cover to hang over the top of the canopy.
• Using scissors, cut away the infected buds from the plant.
• Wear gloves and sterilize your tools to kill mold spores.

Can I Smoke Buds With Mold On?

Absolutely not; get into the habit of throwing the moldy buds into a bin bag and disposing of them well away from your garden. Do not add moldy buds to a compost pile as the spores can still spread through your plants, and infect your healthy compost pile. 

It will be a painful experience to cut out and throw away your best buds that you have been admiring over the last 8 weeks, however smoking infected buds will be harmful to your lungs and health. 

Can Autos and Photoperiods Get Mold?

The short answer is Yes! It does not matter if you are growing out autoflowering cannabis seeds, or photoperiod cannabis seeds. Botrytis will quickly spread to any cannabis plants where the environment favors the fungi. This means that high humidity and poor airflow are the primary factors contributing to the aggressive spread of mold.

Can I Use the Buds to Make Hash With?

Unfortunately you will have to wipe your mouth of infected moldy buds. This means they cannot be smoked, used for making bubble hash, dry sift, BHO or Rosin. Smoking anything that contains mold can cause harm to your health, especially in concentrated form. Never use moldy buds ever!

What About Leaves with Powdery Mildew?

Powdery mildew is another type of fungal disease that infects outdoor cannabis plants at the end of the season. MSNL advises that powdery mildew stands are relatively easy to identify.

The telltale signs are the white, powdery patches that appear on leaves and other plant parts.

You should prune away any infected leaves that show signs of powdery mildew and refrain from using them for hash making or extracts.

My Final Thoughts

Having to throw away moldy buds is a real heartbreaker, and can cause a massive loss in yield and potential trim for hash and extracts. I have also learnt that the biggest and fattest buds on your plants will always be the first to show signs of mold, and are the hardest ones to save. 

Try your best to keep the air flow around your plants as optimal as possible, and protect your buds from light or heavy rainfall. Be prepared to act quickly and remove infected buds, and carefully prune away leaves with powdery mildew. 

Feature image: This plant has a bad case of mold and must be thrown away.

Feature image photo credit: Stoney Tark.