Sometimes the first sign of bud rot is a few leaves on the buds turn yellow seemingly overnight. The base of these leaves is where the bud is rotting
Bud Rot Removal
“When I had to throw away most of my plant due to bud rot, I cried a little, on the inside.”
There are different stages of Botrytis as it matures and tries to release spores. An infection starts as fluffy white mold (or brown mold) and then spreads throughout the inside of vulnerable buds. The inside of those parts of the colas darken to gray or brown. Once that has settled in, the mold tries to reproduce. The insides become filled with dark speckled dust that easily floats and spreads if the bud is cracked open. These are the spores of the fungus, so be careful to avoid breathing in letting this speckled dust ever touch other parts of your plants.
As soon as even one part of a single bud starts showing signs of grey mold, the rot can spread to the rest of the cola and then to other buds on the plant. If triggering conditions (lack of airflow, wetness) have not improved, a single point of infection can quickly ruin the harvest of an entire plant.
Throw Away All Buds with Any Sign of Bud Rot!
Sometimes you might see a few yellow leaves appear suddenly on some of your biggest colas. It can feel like it happens overnight. That could be a sign that there’s mold at the base of these leaves. Always investigate any cola with yellowing leaves ASAP. If there’s mold you will be able to see the leaves are basically falling out, with mold or brown spots being revealed in the middle 🙁
How to Prevent & Stop Bud Rot (quick summary)
How to Stop Bud Rot from Spreading
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!
“If it gets into one plant, watering systems or root beds, they can get the same infection. It can passively spread in the air,” Jones said.
As your grows get bigger, the last thing you need is for crop loss to strike. That’s why you have to educate yourself about bud rot.
“They don’t know why they’re having problems like bud rot,” Tomasini said.
“It’s very common, especially outdoors,” said Dan Kibbin, a Maine-based grower with 25 years of experience. “But I’ve experienced it in indoor grows, too.”
“On the hobby side of things, the two easiest, most affordable things are to make sure you have good ventilation and good air circulation,” Tomasini added, as stagnant air can trap humidity, especially around densely-leafed areas.
- Temperature. The ideal temperature recommended for your grow varies depending on several factors, but keep in mind that bud rot prefers cooler temperatures. Most experts recommend temperatures above 68°F to keep bud rot at bay. In a greenhouse, try to avoid cold nights by using a heater.
- Presence of Spores. If you grow indoors, it’s much easier to avoid Botrytis cinerea spores, but you still should be careful about what you let come indoors. Change clothes before you enter your growroom, and never let pets inside.
- Food Source. Remember that bud rot likes the parts of your plants that have the most moisture, so you’ll need to keep an eye on your denser colas. Of course, if you see infection remove it immediately and don’t let the infected parts of your plants touch those that haven’t been affected.
- Humidity. For indoor growers, limiting humidity is one of the easiest ways to avoid problems with bud rot. (More on this critical topic below.)
Jeff Jones, dean and a horticulture faculty member at Oaksterdam University, described bud rot as “one of the more notorious ruining molds, because you don’t realize it until the plant is basically dying.”
There are a number of ways to think about humidity control relative to crop problems such as bud rot. For outdoor growers, simple tips include avoiding planting in the shade or too close to walls, which can restrict ventilation.
The challenge often comes from growers who go from hobbyist to commercial grower who don’t understand the science of climate control.
The first step to prevent bud rot and other molds is to understand the disease and how it grows and spreads. These four factors create an environment that is ideal for bud rot and we've included some considerations for how to prevent it from taking over your crops.