Unfortunately, by the time that mould is easily visible, invisible mould spores will have contaminated a much larger area. The only way to really get rid of mould, mildew and bud rot on cannabis is amputation; tragic though it is, the parts of the plant that are afflicted must be cut off as soon as the problems have been identified, plus a good area around them to allow for the spores.
Some strains of cannabis are especially susceptible to these problems, for example the Big Bud, simply because the buds are so large and dense; this is the downside of it being such a high-yielding variety!
The optimum humidity varies depending on what stage of life the plants are in. For vegetation, it should be between 40% – 70%; during early and mid flowering, it drops to 40% – 50%; in the final stages of flowering, less than 40% will help to prevent cannabis moulds and powdery mildew.
To help prevent mould and fungus on cannabis growing either indoors or outdoors, the airflow through the plants and around the buds can be increased by carefully trimming off large fan leaves and any branches without any buds on them.
There are few things worse than lovingly nurturing a crop of cannabis through vegetation and flowering, only to have mould strike in the last weeks before harvest. Unfortunately, this span of time is exactly when the most common types of cannabis rot and mould infections usually occur. Knowing the reasons for this also suggests how to prevent them occurring.
Some are more resistant, such as the Early Skunk. For growers without much experience, choosing a hardy, mould resistant strain is a good idea to give more chance of success.
Not only is it very unhealthy to inhale or consume the spores, if they are left on the plant then the same problems will continue.
The best ways to tackle the problem are removing any mulch, straw, or random vegetable matter from around the bottom of the plants, and increasing the airflow around and between the buds, as detailed below. If they are in pots, bringing them to a sheltered, covered place when it is raining is worth trying.
Indoors, make sure there is sufficient airflow using oscillating fans and a strong air outflow. It is simple to tell if there are areas of stale air because the plants will not move in those places. There should be gentle but visible movement of the fan leaves and smaller branches.
Curious if you have a case of bud rot? Wondering what mildew looks like? Hoping to avoid creating the ideal conditions for mould? Sensi Seeds tackles the main causes of the main problems, and how to identify them, when it comes to cannabis going bad.
If you can’t fix the environment, I highly recommend cutting your losses at this point. If you know that it’s still going to be cool, humid or wet for your plants, it’s recommended you harvest immediately to prevent further buds from becoming infected. Buds harvested early are better than moldy buds!
A good outdoor strain for those worrying about bud rot might be Auto Frisian Dew, an award-winning, mold-resistant strain made for outdoors. This strain goes from seed to harvest in about 12 weeks. Just plant seeds after the last frost in the Spring, then harvest 3 months later.
Get a strain meant for your local climate. If you live in a place that has short summers and gets humid or rainy early in the fall, don’t get a strain that was developed near the equator!
Did you know? In addition to cannabis bud rot, Botrytis causes problems for many different types of plants, including wine grapes, strawberries and peonies.
How does the Botrytis fungus get to my plants?
The Botrytis fungus looks white and fluffy in its initial stage, but you’ll probably never even see this stage before the mold quickly darkens and starts rotting the buds from the inside out
What Causes Bud Rot?
There’s nothing you can spray on your plants after bud rot has already formed. Unfortunately, there aren’t any effective fungicides or other treatments that are safe to use with cannabis in the flowering stage
Cannabis bud rot is caused by a type of fungus known as Botrytis cinerea.
Bud rot is a mold that develops in the thickest parts of cannabis buds. Read for more information on how to prevent and solve bud rot before spreading!