Cannabis Cultivation

How to Fight and Prevent Cannabis Bud Rot?

Cannabis Bud Rot goes by many different names as bud rot is not the scientific term for what bud rot actually is. Bud rot on cannabis is actually called botrytis. This is a type of fungus that grows on many types of plants in gardens, not just cannabis crops.

What is Bud Rot (Botrytis)?

Bud rot grows inside of dense cannabis buds. Growing can get it on their cannabis plant both indoors, and outdoors. Bud Root can be very hard to see when it first starts. This is because it will generally start inside the flowers of the cannabis plant, where it is the most humid. Normally growers will not see bud rot on their cannabis flowers until it has spread throughout the entire bud.

If you do see bud rot early in the process it is possible to stop it from spreading to other plants and buds on the same plant to prevent cannabis bud rot. Once the plant has been taken over and the rot becomes too widespread in the flowers, the flowers will have to be destroyed.

Cannabis Bud Rot

What does Bud Rot Look Like?

At first bud rot is far too small to see on your buds, it will take millions of spores to get it to the point a grower can see it on their buds. As the bud rot progresses, it will first show up inside the buds as a white webbing that looks somewhat like a dense spider web. To see it in the buds at this point you would have to push the bud aside to see the white mold

As the bud rot progresses it will turn a darker gray color. The areas around the bud that is being attacked will start to turn, mushy, yellow or even look burnt. At this point the botrytis spores will have started to spread to other buds on the plant. Keep a look out for white spores on the other buds, they will travel by touch, air flow indoors. Outdoors they can travel in water droplets, bug pollinators and storm winds.

Things to watch out for in the grow room:

  • Red Dead leaves coming out of otherwise healthy looking buds
  • Gray or white looking mold around you buds
  • Buds that look mushy, yellowing
  • Rotten buds on a cannabis flowering cola
  • Buds and leaves that look suddenly dead and burnt for not apparent reason
  • When smelling your buds, there is a foul smell overriding the smell of the fresh buds
Bud Rot on Cannabis Buds

Will Bud Rot Attacked Vegetative Cannabis Plants

Botrytis can attack vegetative cannabis plants, especially if the plant is sick or unhealthy. In the vegetative stage of growth it will normally attack near the base of the cannabis plant’s main stock. It will look white and cover the main stem, slowly cutting off nutrients and killing the whole plant. This is far less common than getting bud rot in your cannabis buds.

Where does Bud Rot Come From?

Bud rot comes from other spores in the area, however they are environmental factors that can help the spread of mold. The two main factors are poor room ventilation and high humidity, both of these things can help the mold to grow faster and spread throughout the grow room. These will contribute to mold growing in your buds. Some of the environmental factors are warm temperatures, dense foliage with little air movement and unhealthy plants. 

These things will help the mold spores germinate inside your buds.

Cannabis Bud Rot
Cannabis Bud Rot inside the Flower

How to Keep Cannabis Bud Rot out of your grow room?

There is no sure fire way to keep mold out of your grow room, there are things you can do to help prevent it from getting into the room in the first place. Keeping the room clean will go a long way to keep bud rot out of your buds. Using ISO alcohol to keep things clean will kill mold spores before they have a chance to get into your plants. Scrubbing down the walls of your tent or room will clean spores between each grow.

Removing Death Matter

Removing dead organic materials from the room as they die. Never leave dead leaves or branches hanging in the grow room. Mold is actually part of the ecosystem because it breaks down dead stuff in nature. If you have dead things in your grow space the mold will attach itself to it, and will start to break it down while also spreading new mold spores to your buds. This is especially important if any of the dead material is touching your growing cannabis.

Keeping your grow room Humidity Low

Mold loves to grow in warm humidity conditions. Growers can use this to their advantage by keeping the grow room humidity in flowering about 40%, also keeping the grow room a bit on the cooler side will also help keep mold out of your grow room. If you are unable to keep the temperatures down and humidity you may need to invest in Air Conditioning for your grow space.

Wearing Clean Clothes and Shoes into the Grow room

The majority of the time mold spores get into the grow room attached to the grower, the growers animals, or from outdoors on the growers shoes. You can help prevent this from happening by keeping clean clothes to use in the grow room, not wearing outdoor shoes into the grow space and keeping pets out. The best way to keep bud rot out is to not bring it in. 

If you have touched any places that had bud rot make sure to wash your hands really well to kill any of the spores that could be attached to your hands.

Keeping Cannabis Plants healthy to Keep them Bud Rot Free

Keeping your plants healthy during flowering will also help to prevent mold. Keeping the plants apart with enough space between them will help to keep the humidity down, and keep air flowing well between each cannabis plant. Moisture will also build up on any plant leaves that are overlapping each other. Defoliating Cannabis before it starts to flower can help with these issues and prevent mold.

To help keep your humidity low only when needed for the plant and limit runoff in the grow room. The less water laying around on the floor, the less of it evaporates into the air. Healthy plants can battle mold much easier then sick or unhealthy plants, learning to grow the plants properly and making sure to keep them growing well will go into helping them fight off bud rot.

Cannabis Bud Root Top

Outdoor Cannabis Bud Rot Prevention

Since growers are unable to control environmental growing conditions growing outdoors, you must work to keep the plant healthy. Removing all internal leaves and branches can help outdoors with air flow to keep mold from growing on the plants. Keeping the plant’s bottom foliage clean and off the ground will help to not pick up any bacteria or mold that is on the ground.

When it rains the mold spores can splash off the ground and up onto the cannabis plant’s bottom leaves, by keeping the bottoms of the plants free of vegetation this will prevent this from happening. It is also helpful after a rain to shake the rain water off the plant that is sitting on the leaves and the flowers of the plant. 

If you live in an area that has a very wet fall, you can also construct a tarp overtop of your plants to keep rain off them in the fall. It will be important to remove it after the rain stops to allow the sun to dry the plant and return good airflow. This will help to temporarily keep rain and moisture off the plant when it is in full flowering.

Important Mold Prevention List for Cannabis Outdoors:

  • Stake the plant up to keep it from touching the ground
  • Space the branches well to keep good air flow inside the plant
  • Defoliate the plant before it starts to flower outdoors 
  • Place the plant will it will not sit in the shade, or near standing water

Indoor Cannabis Bud Rot Prevention

When growing cannabis indoors it is much easier to control the environment. Doing so will prevent mold much easier than outdoors. 

When watering cannabis indoors never get water on any of your buds, and only water the plant as much as needed to prevent sitting or pooling water. If you do get water on your buds be sure to dry the plant off after. Having a good fan in the grow will help move the air and keep a good air flow in the tent or grow room. 

As with outdoors healthy thriving cannabis plants are able to better fight off mold when the spores try to attack the plant. Keeping the climate constant is of the utmost importance, so keeping the temperatures consistent, and using dehumidifiers if the grow room climate is overly humid for any longer than a couple of days during the flowering periods. 

Good ventilation by removing stale air from the grow room is also very useful in keeping mold to a minimum in your room.

Important Mold Prevention List for Cannabis Indoors:

  • Keeping the grow room at a low humidity during last weeks of flowering
  • A large enough fan to keep the air moving well through the plants
  • Watering your plants as soon as the lights come on, rather then before they turn off
  • Never leaving any pooling water in the grow room
  • Using a dehumidifier when needed to keep the humidity low
  • Keep the plants spaced out well from each other
Cannabis Bud Rot Indoor

How fast can Bud Rot Spread in your Cannabis Buds?

Once cannabis bud rot is in your flowers it doesn’t take very long to spread in your buds and move to other plants. Once the spores have taken hold it can take as few as 3 to 4 days to completely take over your plants. This is why it is so important to recognize bud rot and deal with it as quickly as possible. 

What to do if you get Cannabis Bud Rot on your flowers?

First identify where the mold is, how much of the plant is affected, and how developed it is. Once the grow has checked this, it will be time to decide if you can savage the plant. If you can’t savage the plant you will have to remove it from the grow room as carefully as possible. There will be spores that will get released onto the other buds, so when removing it do so slowly so as to not disturb the plant and mold. If the mold is all through the main buds it is best to just remove it and cut your losses. 

If the mold is only affecting one or two buds then it can be removed. Start with pruning the buds that have any but rot on them with your pruners. Make sure to remove any buds that have been affected. After you have removed all the bud rot, make sure you clean your pruners very well with ISO alcohol. Scrubbing them well so there are no spores left alive on the pruners. 

Then fill a spray bottle with water and hydrogen peroxide. Take the spray bottle and spray all around the affected area to kill any mold, spores that you can’t see. Then use a paper towel to remove as much of the solution as possible from the buds. Use the fan to dry out any flowers that have not been removed.

Dealing with Cannabis Bud Rot post Harvest

Once your cannabis buds have been harvested, it is a very important time to prevent mold from ruining your beautiful crop. Once the plant has been harvested check it over well to make sure there are not mold in your buds. 

It’s a great idea either indoors or outdoors to let the plants dry out for a couple of days before you start your harvest. Never harvest outdoors after it rains, or first thing in the morning. Wait for the plants to have a dry sunny day before harvesting to rid the plant from as much moisture as possible. 

Once the plant has been cut, creating the best conditions for drying as you can, this means keeping the temperature in the drying room about 60F (15.5C) to 70F (21C). 

If you know that you have had bud rot problems post harvest in the past it can be a good idea to keep the humidity in the drying room a lower for the first couple of days. Once the plant has started to dry well, you can then return to a slower drying process for better buds.

Most Important Thing to Prevent Cannabis Mold

Now that we have reviewed how to prevent and stop mold, the most important thing you can do in your grow room to stop bud rot is to stay vigilant. Make sure your room is kept in check all the time, these days it is easy to order grow tools that can keep track of the grow room environment remotely through the internet. Watching for any signs that mold is getting a foothold in the plant so you can remove it can be the difference in saving your plant vs having to destroy it and losing your crop.

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