What Makes Cannabis Plants Grow Smooth Leaves? Re-vegging.

What does it mean to accidentally “re-veg” a cannabis plant? “Re-veg” is short for “re-vegetation” and refers to what happens if a plant that has started flowering re-enters the vegetative stage. The majority of cannabis plants are photoperiod strains, which need long nights in order to make flowers/buds (indoor growers typically give 12 hours of uninterrupted darkness a day). If the plant starts getting light during its night time it responds by re-vegging.

Sometimes even just a little light like a blinking LED in your grow tent, or checking on plants during lights-off is all it takes to interrupt your plant’s beauty sleep. For outdoor growers, the light from a street lamp or window can be the culprit.

Re-vegging happens when flowering plants get light during their 12-hour dark period. A few interrupted nights or even a small light leak can start a re-veg!

Re-vegging cannabis plants show odd leaf symptoms such as:

• smooth leaf edges
• buds stop developing
• long leaves or new stems grow out of bud sites
• main stem sprouts 1-point leaves (just one “finger” per leaf instead of the typical 7 or 9 for adult cannabis leaves)
• curling leaves (may look like heat stress)
• wrinkled, twisted, or unusual growth

This plant was put outside too early in the Spring season, which caused it to start flowering due to the short nights. As Spring progressed the nights grew shorter and it began revegging, growing these oddly smooth leaves directly out of the center stem.

Unusual single-point leaves started growing out of the developing buds of this plant in the middle of the flowering stage. The grower didn’t realize that turning the light on for a few moments during the dark period could cause a problem. If the plant is getting light at night, it only takes a few days to “flip the switch” and initiate the re-vegging process!

Some revegging symptoms include wrinkling, curling, or twisted leaves. These symptoms may be confused for watering, heat problems, or even broad mites, when they’re actually a sign the plant is going through major internal changes. Notice the wrinkled leaves in this picture are more smooth around the edges than typical leaves. That’s a key sign this plant is re-vegging.

This plant was already flowering indoors, but when it was brought outside in the spring, the short nights caused it to start re-vegging almost immediately.

These clones were recently taken from a flowering plant and have started re-vegging, causing odd growth and some smooth-edged leaves. Like many of the other cases of re-vegging, you can also see several single-point leaves among the new growth.

This outdoor cannabis plant started re-vegging, resulting in odd, twisted growth as well as smooth single-point leaves with long stems. It started revegging because it was growing near a window in the house that was shining light on the plant.

This plant was given a 12/12 light schedule after germination and buds (white hairs) started to form. The grower realized he wanted a bigger plant so he switched to a 20/4 light schedule so the plant would re-veg. Buds stopped developing and single-point leaves started growing out of the buds. Although you can still see a few white hairs, it is almost fully back into the vegetative stage at this point.

The leaves of a re-vegging plant may look different depending on the environment and particular strain. Ultimately, you know it’s the symptoms of re-vegging when the leaves appear more smooth than typical leaves. There really aren’t any other cannabis problems that cause that particular symptom.

Each cannabis plant expresses re-vegging a little differently!

Sometimes marijuana growers choose to re-veg their plants purposely, for example monstercropping (taking a marijuana clone from a plant in the flowering phase in order to change the clone’s initial growth patterns) or to harvest a plant for a second time (put it back into the vegetative stage and grow the whole plant out again after harvest, sometimes used by outdoor growers in warm climates to get a second harvest in a year).

Unfortunately, most of the time a grower sees the tell-tale leaves of a re-vegging plant, it’s an unwelcome sight!

What to Do About Accidental Re-Vegging

When a plant is revegging, you basically only have two choices.

1. Let it re-vegetate completely if you actually want the plant to be in the vegetative stage, or…
2. Correct the light periods by getting rid of any possible light leaks and giving plants 12 hours of interrupted darkness a day (to get them to go back into the flowering stage).

Plants that are far in the flowering stage can take a month or more to re-veg, while a plant that has only just started flowering re-vegs much faster. That goes both ways. If a plant has been re-vegging for a long time, it may take a few weeks to get the plant back to flowering and developing buds.

Luckily, a little time and proper care will get your plant growing normally again!

This cutting was taken off a flowering marijuana plant and put in a cloning device so it would re-develop roots and grow into a new plant. After a few days of growing, it started producing the typical rounded leaves of a re-veg.

About two weeks later, the plant is growing (mostly) normal leaves. Cannabis plants tend to grow a lot of stems and get bushy immediately after a re-veg, which can be seen heree. Although the growth patterns were odd at first, from this point on, the plant usually has relatively typical growing patterns.

Re-vegging cannabis pictures by Don B

If you see your cannabis plant re-vegging, don’t panic! Figure out whether you want your plant to be in the vegetative or flowering stage and act accordingly. A little time is all it takes after that to get your plant in tip-top shape again.

The post Accidental Re-Vegging appeared first on Grow Weed Easy.

Table of Contents

Male vs Female: Why to Avoid Males, Hermies & Bananas

Seedy Buds Can Be Caused by Two Different Types of Hermies

• “True” Hermaphrodite Plants
• Bananas (“Nanners”)

How to Avoid Causing Hermies or Bananas

by Nebula Haze

Remove plants with both male pollen sacs and female flowers (hermies) to avoid pollination/seeds!

You may also see yellow “bananas” (stamens) growing around the pistils/hairs of the buds. A stamen normally grows inside a male pollen sac but sometimes appear directly on female buds, especially in times of stress. A stamen produces pollen and doesn’t even need to open up before it starts making seeds! Remove plants immediately if they start growing bananas (also referred to as “nanners”) or your entire grow room may get pollinated. No one wants to be surprised by seedy buds after harvest.

This highly stressed plant (from heat and too much light) grew a banana in a last desperate attempt to make seeds

Certain cannabis plants will herm even if healthy and unstressed. This is a genetic trait carried by some strains and particular plants. That’s part of why it’s important to grow seeds from a trustworthy breeder. For example, every clone of the following plant grew bananas in week 3 of the flowering stage, under no stress, in multiple different grow setups. When herming is part of a plant’s genes, there’s not much you can do.

These bananas weren’t triggered by stress. Herming is simply part of this plant’s genetics. The brown hairs are already pollinated.

Here’s a closeup of a herm banana

This poor hermie has male pollen sacs growing among the female flowers. It’s recommended to immediately toss any plant that shows both male and female flowers!

Male vs Female Cannabis Plants: Introduction

Cannabis Life Stages and Sex

Did you know there are “male” and “female” cannabis plants? Cannabis plants are “dioecious” plants, which means each plant shows a particular sex, just like humans and many animals. There will occasionally be plants that show mixed-sex and these plants are often referred to as hermaphrodites or “hermies”, which I will explain in much greater detail below.

The sex of a particular plant matters quite a bit to growers. That’s because only female cannabis plants produce buds. In fact, the “buds” that we smoke are actually the female flowers of the cannabis plant.

The highest quality bud is considered to be “sensimilla” and refers to female cannabis buds that have not been pollinated by a male cannabis plant. The word “sensimilla” actually comes from the Spanish phrase “sin semilla” which roughly translates to “without seeds.”

Learn more about male vs female marijuana plants

Regular marijuana seeds will usually be about 50% male, and 50% female. That means half of the seeds will be unusable as far as growing buds. Please note that some male cannabis plants (about 70% of male cannabis plants according to some estimates) may produce a small amount of useable THC via trichomes growing on the outside of the plant. Unless you’ve seen the males in your plant’s family tree, there is no way to know for sure if a particular male plant is going to produce THC/trichomes. Even if it does it will be a much, much lower amount than a female cannabis plant producing buds.

If you have a male plant and you are trying to grow bud, I strongly, strongly recommend throwing the male plant away immediately and starting another seed or focusing on your other plants. It’s a waste of time to grow male plants for THC or other cannabinoids – they don’t grow buds!

Here’s a picture of a male cannabis plant – no buds or trichomes, just pollen sacs!

Quick Tip: How do you make sure you only grow female plants so all your plants produce buds?

One way around the issue of having 50% male and 50% female plants is to purchase feminized seeds online. These seeds are available from all reputable online seedbanks, and the plants produced by these seeds are always female. Get your questions about buying seeds online answered! You can also make your own feminized seeds, but you have to start with two known female cannabis plants.

It’s difficult to look at a young cannabis plant and know its sex

For the first part of your cannabis plant’s life, it will be in the first stage of growth known as the “Vegetative Stage.” In this stage, your plant will only grow leaves and stems, but no buds or flowers. Think of this as the time when your plant is gaining size to prepare for the second stage of life.

A young vegetative cannabis plant is unlikely to reveal its sex until it’s at least 3-6 weeks old, and sometimes even later than that.

Unfortunately, it’s difficult to determine the sex of a cannabis plant when it’s a young seedling. Although there is genetic testing that can be used on plants as young as 1 week old, most growers aren’t going to go that route. At a certain point, most strains will “reveal” their sex via pre-flowers at the joints. This can occur as young as 3 weeks old with male plants, and around 4-6 weeks old for female plants. This is normal and is just a sign that your plant is fully mature and ready to start flowering. Learn more about preflowers.

Another great option is to use clones. Cuttings (clones) taken from a female plant will always turn out to be female. Sometimes clones are showing preflowers by the time they’re rooted as a clone. We also know that when you breed two female plants together, you end up with feminized (all-female) seeds.

So, unless you start with a known female clone or feminized seeds, there’s no way to know what sex your plant will turn out until it actually starts showing signs of sex organs. This happens in the second stage of your plant’s life, known as the “flowering stage.” The first sex organs that appear are often called “pre-flowers.”

When do cannabis plants reveal their sex?

In addition to looking for preflowers, all cannabis plants reveal their sex when they reach their second stage of life, known as the “Flowering Stage”.

The first sign of sex almost always appears at the “V” where new growth tips form from a stem, like this….

See the little growths appearing at the “V” or “crotch” where the growth node meets the stem? These are the first sign of “pre-flowers“. In this case, we can see the pre-flowers are forming, but it could be tough to tell whether this plant is going to turn into a boy or a girl quite yet. (Note: It’s a boy)

Younger plants (that are less than 6 weeks old or haven’t shown preflowers yet) tend to take a little longer to switch into the flowering stage compared to older, more mature plants that have been vegetating for a while. Other than that, you can pretty much force a cannabis plant to start flowering no matter the age, even 2-3 weeks after the seed was germinated.

Read the full article about male vs female cannabis plants (and learn how to use cloning to identify the sex of young plants while they’re still in the vegetative stage – advanced only!): https://www.growweedeasy.com/marijuana-boy-girl

When Sex Isn’t as Certain… Avoid Accidental Pollination!

So now you know that most cannabis plants are normally considered to be either “male” and “female.” Yet sometimes you will run into plants that show both male and female characteristics, and these plants can accidentally self-pollinate, or pollinate your other female plants.

A cannabis plant that shows both male and female parts is often referred to by growers as a hermaphrodite or “hermie.” These can pollinate your plants and cause seedy buds.

There are a few different types of mixed-sex plants, and it’s important for a grower to understand some of the biggest differences so they make the best decision possible when faced with hermies.

Important: It’s not advisable to breed mixed-sex plants to create seeds because their offspring are more likely to display hermie characteristics.

Hermaphrodite Plants

Although growers will refer to all mixed-sex plants as “hermies,” there are technically two different kinds: hermaphrodite cannabis plants, and mixed-sex buds (like buds with nanners). The only reason I bother to differentiate between the two is that true hermaphrodite plants are more predictable.

With a “true” hermaphrodite plant, the male and female parts will grow on different parts of the plant. They won’t grow together in the same spot such as when nanners appear in the middle of buds.

Here is an example of a true hermaphrodite plant – notice how this hermie has both female pistils and fully formed male pollen sacs

What causes it? Stress can trigger this type of hermaphroditism, but unlike bananas, this particular type of mixed-sex plant seems to be a little bit more stable based on the plant’s genetics. It usually doesn’t take stress to cause these to appear. They’re more like a natural trait of the strain. A clone of a true hermaphrodite plant will often also turn into a hermaphrodite, and offspring will often show the same traits even under perfect environmental conditions.

It is recommended to never breed a plant that shows hermaphrodite traits since this is a highly inheritable genetic trait. A good “breeding stock” mother will not show signs of hermaphroditism even when subjected to stress.

What should the grower do? It is recommended that you remove hermaphrodite plants from your grow room or grow area as soon as possible to prevent accidental pollination of the buds.

If pollen from a pollen sac is allowed to make contact with your buds, those buds will stop focusing on making more buds and will turn all their “effort” into making seeds. No one wants seedy buds and reduced yields!

Unlike bananas, hermaphrodite plants tend to be more predictable. Though it’s not advisable, a grower who watches very closely can carefully pluck all pollen sacs before they’ve burst. However, this should only be done if it’s the only plant you have! Don’t do this if you have other female plants that can be pollinated!

Remember, while these pollen sacs can start appearing early, they may continue to appear throughout the flowering stage so stay vigilant!

The following type of hermaphrodite plant has mixed male and female parts, referred to in botany as “bisexual” flowers.

With mixed-sex buds you will see plants that grow a mix of pistils and pollen sacs together, like this…

Bananas (“Nanners”)

Another common type of mixed-sex buds is the type that produces “bananas” (sometimes called “nanners”) which grow from the middle of female buds.

Example of a “Banana” or “Nanner” growing among buds

Bananas are rarely round and they don’t look like a normal pollen sac. Instead, they’re often elongated and yellow, which is where they get the nickname “banana”. They may grow together in bunches that can look like a bunch of bananas. Occasionally they appear more lime green than yellow.

Sometimes a banana appears lime green instead of yellow

picture by DW2

These can be a lot more difficult to control than actual pollen sacs, since they may start pollinating everything in the area as soon as they appear. A few bananas won’t do much damage, but if you have a big banana problem it may be best to harvest the plants immediately and cut your losses. Seeds take some time to develop, so if a plant starts herming right around harvest time, it’s less likely you’ll end up with seeds.

Just like real bananas, they can appear in bunches

What are they? Bananas are actually the exposed “male” parts of a pollen sac, called the “stamen” which would normally be surrounded by a sac to hold all the pollen until it bursts open. If you open up a fully formed male pollen sac, you will see what looks like bananas (stamens) inside.

But when bananas appear on your plants, they don’t need to “burst” in order to spread pollen, they will immediately start making pollen and often will seed the buds that are close by even if bananas are removed right away, and sometimes the pollen can drift to other plants and pollinate them as well, too.

This banana appeared a few days after the grower used the bud back building technique (cutting off the top tip of all buds to try to get them to grow more fat and round). Apparently, the plant felt attacked

This is what it looked like after being picked off

It’s possible that the pollen is sterile, and won’t pollinate bud successfully…but don’t rely on that happening!

The yellow bunches in this bud are bananas/stamens and will “try” to pollinate everything they can – they don’t have to wait for a pollen sac to burst. It’s possible that the pollen is sterile, but often you may find seeds.

If a female plant is allowed to go too long without being harvested or pollinated (allowed to go past the point of optimal harvest), she will sometime produce a bunch of bananas in her buds as a last-ditch attempt to self-pollinate and create seeds for the next year. This is sometimes known as rhodelization. This is not as destructive as other types of hermies since it only happens after plants are already past the point of optimal harvest.

What causes it? While genetics are ultimate the cause of whether a plant is capable of producing bananas and mixed-sex buds, environmental stress is often a big component in causing bananas to form. Luckily if you stick with high-quality genetics, you are much less likely to run into bananas even if you do accidentally stress your plants. Not all bananas are “fertile” and you may see them without ever getting seeds.

Male hermie banana growing among the beautiful buds 🙁

What type of stress can trigger bananas to form on cannabis buds?

• Inconsistent Light Schedules & Light Leaks – When plants don’t get light at the same time each day, or if they’re exposed to light during their dark period (light leak). For photoperiod plants, this might be the largest contributor to hermies.

• Temperature – When temps get too high, hermies and nanners often appear. Cold night temps, or just large temperature swings in general, are also known to trigger bananas for some strains.

• Too-Bright Light – Like too much heat, and/or light that is too bright can stress your plants and trigger hermies. This is most often caused by growers keeping their lights to close to their plants. You can light-burn your plants even when the temperature is under control.

• Major Plant Problems – Major plant problems like nutrient deficiencies, root rot, pH problems, light-burn and nutrient burn can all trigger hermies to start growing.

• Genetics – While stress plays a big role in the formation of bananas, the tendency to form them is genetic. This tendency is very common in the seeds of a plant that hermied.  “Feminized” seeds, while always female, are much more likely to show the same herming traits as its parent. Growing seeds that were produced this way is naturally selecting to produce more buds that grow bananas. Only get feminized seeds from a trusted breeder.

What should the grower do? It is recommended that you remove plants showing bananas from your grow area immediately to prevent accidental pollination of buds. If the pollen being formed is allowed to make contact with your buds, those buds will stop focusing on making more buds and will turn all their “effort” into making seeds. If the plant self-pollinates, you will end up with a bunch of sub-par seeds that are likely to have the same problem.

Of the different types of “uncertain sex” cannabis plants, plants with mixed-sex buds (especially hermies with bananas) are the least predictable and this can make them more likely to cause unwanted pollination. This is partially because bananas may be hidden in the buds, and they don’t have a pollen sac that needs to burst to pollinate buds – it will start pollinating almost immediately.

A grower who watches very closely can carefully pluck all bananas, but they are unlikely to be successful and will probably end up with at least a few seeds.

Trying to salvage a plant that has started producing tons of bananas is NOT recommended, because it’s hard to get them all and you’ll end up with seeds. Even worse, once a plant gets started, bananas can appear in huge bunches overnight especially when the plant is stressed. Harvest the plant as soon as you can, before seeds get a chance to start forming.

How to Avoid Causing Hermies or Bananas

This section will explain what you can do as a grower to reduce your chances of running into hermies or bananas in your grow room…

1.) Avoid Inconsistent Flowering Light Periods & Light Leaks

• Keep indoor lights on timer, and avoid changing the light schedule during the flowering stage if possible.

• Prevent outdoor plants from being exposed to street lights, flood lights or other types of artificial lights during the night.

• Respect the dark period – In the flowering stage it’s important to make sure all your plants (except auto-flowering strains) get at least 12 hours of uninterrupted darkness every night. Avoid shortened dark periods and light leaks!

No matter the strain, try to keep your plants on a consistent schedule throughout their lives, as this helps them set their circadian rhythms.

And for photoperiod plants in the flowering stage, do not interrupt the plant’s 12-hour dark period with light for any reason.

Why? During the dark period your plant is “counting” the hours until sunlight appears, and interrupting this process is one of the most common ways to stress the plant into producing bananas or hermies. It can also cause your plant to revert back to the vegetative stage.

Along with the point above, make sure you do not have any light leaks in your grow space, which could allow outside light to sneak in during the dark period. During the dark period your plants like complete darkness.

If anything ever happens with your timer or power that causes your plant to get too much light or darkness, it’s important to correct your timer as soon as possible. But don’t worry about it too much if it happens just for one day. It’s usually okay if it happens only once, but be careful not to let it happen again since messing up the light schedule can cause hermies. It’s better for a plant to get a too-long day than a too-short night period in the flowering stage. So, for example, it’s better for it to get an 18-hour day than a 6-hour night. Cannabis plants “count” the hours of the night period, so it’s most important to make sure the night period is at least 12-hours long (longer is better than shorter for night periods).

2.) Maintain Proper Temperature Through Flowering Stage

• Maintain a comfortable temperature in the flowering stage, between 65-85°F (18-30°C).

• Avoid big temperature swings – temps should be slightly cooler at night than during the day.

• Don’t let the plant (and their roots) sit directly on a cold floor.

Always use “hand-test” to make sure it doesn’t feel too hot in the top canopy of buds under the light. Put one of your hands (palm facing down) under your grow lights where the top of your plants are located and wait 10 seconds – if it feels too hot for your hand it’s too hot for the plants! Be careful of cold drafts at night in cool climates during the winter.

Learn more about temperature here: https://www.growweedeasy.com/temperature-growing-cannabis

3.) Don’t Give Your Plants Too Much Light (Light-Burn)

While generally more light is better for your cannabis plants, very high power brightness can light-burn your plants, which stresses plants, causes unwanted bleaching, and can trigger the plant to hermie on you.

With high power LED grow lights and big HID lights, make sure to always follow the manufacturer’s specifications as far as the minimum distance from the top of the plants!

Don’t keep your lights too close because even if the heat is under control, too much brightness can cause stress too.

Light-burn is only common with high power LEDs (3W chipsets and bigger, x-lens technology, COBs,  etc.) and big HIDs or perhaps multiple smaller HIDs (usually with an intense cooling system).

It is more difficult to “light-burn” your plants with fluorescent lights, CFLs, smaller HIDs, etc. – with these lights, you only need to worry about heat.

High Power LEDs or HID Grow Lights Will Light-Burn Plants When Kept Too Close
(yes, even if the temperature is completely under control)

Learn more about giving your plants too much light

4.) Prevent Major Plant Problems

Major stress to the plant can cause the plant to react in unpredictable ways, including producing bananas and male pollen sacs. Major stresses include…

• Major nutrient deficiency

• Nutrient Burn – given too much nutrients

• Pest infestation

• Total leaf loss (usually as the result of overzealous defoliation or bugs)

• Any other huge stress to the plant

Want to read about a real example?

The plant pictured to the right was subjected to cold temperatures and then grew directly into the grow light, putting it under a lot of stress.

From the grower Saberabre: “So I left this girl (or what I thought was a girl, notice the pistils at the bottom calyx) over the weekend and came back to the plant up in the light getting burned. Yikes! I’m not too sure what happened here but it got pretty cold the last few days. I think it’s a hermie…”

A few days before this pic, the plant was just showing a few white pistils and appeared to be female.

After the stress that it went through, the grower came back to a plant that was completely covered in male pollen sacs, with the first few white pistils being the only sign of this plant is female.

5.) Always Start with Trusted Genetics

Hermaphroditism and mixed-sex buds seem to be more common when growing plants from bagseed (seeds that you find) or seeds from an unprofessional breeder.

Do feminized seeds cause hermies?

The reason is that seedy buds are worth less than sinsemilla (unseeded buds). Therefore, if you find a seed in your bud, it likely was the result of either bad growing practices (male plants weren’t removed in time) or due to some type of problem (plants were stressed and self-pollinated, which means the next generation is most likely to do so).

When you’re buying seeds from a trusted breeder, they go to great lengths to prevent unintended pollination, and they specifically select for plants that don’t ever show mixed-sex traits.

Which cannabis breeders can I trust?

And remember… even if you do everything right, sometimes you will run into hermie plants – it’s just a fact of growing. Sometimes these things just happen, for example…

“I’ve always felt like seeded weed was not nearly as potent as sinsemilla and I do everything in my power to kill all males! Cannabis is so sneaky, though – last summer we had such wild weather that even a couple of clones turned out some male sex parts.”

~ Experienced outdoor grower

Jump to…

Male vs Female Cannabis Plants

What do I need to get started growing indoors?

Take a look at cannabis grow journals

Where can I buy feminized seeds?

“Cannabis has both male and female plants. When both female and male flowers are in bloom, pollen from the male flower lands on the female flower, thereby fertilizing it. The male dies after producing and shedding all his pollen. Seeds form and grow within the female flowers. As the seeds are maturing, the female plant slowly dies. The mature seeds then fall to the ground and germinate naturally or are collected for planting the next spring.

“Unpollinated, female cannabis flowers continue to swell and produce more resin while waiting for male pollen to successfully complete their life cycle. After weeks of heavy flower and cannabinoid-laden resin production, THC production peaks out in the unfertilized, frustrated sinsemilla!”

~Jorge Cervantes in Indoor Marijuana Horticulture

The post Hermies, Pollen Sacs & Bananas appeared first on Grow Weed Easy.

by Nebula Haze

Cannabis bud rot (aka “Big Bud Disease” or “The Curse of the Successful Grower”) attacks your fattest, biggest marijuana buds right as they start to approach harvest time.

Too cruel… Bud rot attacks and kills your biggest, thickest buds. Often the first sign of cannabis bud rot is the leaves on a big bud suddenly die or turn yellow often over the course of 1-2 days. The base of these discolored leaves is where the bud is rotting. If you investigate closer, you will often be able to see the mold.

by Nebula Haze

How to Prevent & Stop Cannabis Bud Rot (quick summary)

• Avoid wet buds & high humidity – Bud rot is a fungus, and like all fungi, its spores needs a wet, humid place to germinate and grow. About 40-50% RH is ideal for the cannabis flowering stage (both for dense buds and to prevent bud rot). A humidity above 60% RH puts you at major risk of bud rot and mold, especially if you have lot of thick buds. Don’t allow buds to sit in damp or overly humid conditions for long. Indoor growers can use a strong dehumidifier to reduce humidity in the grow space if necessary. Outdoor growers can cover plants when it rains and shake them off when they’re wet. Another strategy for outdoor growers is to get short-flowering (ex: Pineapple Express) or auto-flowering (ex: Purple Punch Auto) strains so their plants are ready to harvest before the start of the local rainy season.

• Great air circulation – Air should be moving over the buds and leaves as well as through the plant. Fans are a huge help indoors, especially if you set up an exhaust fan to vent hot humid air away from your plants. Oscillating fans can help prevent humid spots but only blow air around so they can’t lower the overall humidity. Outdoor growers can move potted plants to a breezier location but if plants are in the ground, unfortunately, there’s not much you can do to increase air circulation.

• Defoliate extremely bushy plants – Each leaf is constantly adding water vapor to the air. That means removing leaves can help lower the humidity through and around the plant, especially in a small growing space. If you decide to defoliate because plants are covered in tons of leaves and the humidity is high, remove leaves that aren’t getting much light (typically the middle and bottom of the plant) since they aren’t making food for the plant anyway. 

• Watch long, dense buds for signs of discoloration – Almost like a cruel joke, bud rot usually attacks your biggest and most impressive colas 🙁 That’s why cannabis bud rot is sometimes known as “The Curse of the Successful Grower”.

• Remove all buds affected by bud rot immediately – Carefully remove and discard all buds with bud rot, as well as nearby buds. This is a fungus that can spread quickly. Don’t let any of the dusty rot touch other parts of your plant to avoid spreading mold spores.

• Consider harvesting early – If you can’t fix the environmental conditions that caused the bud rot (for example if it’s wet or humid and you can’t do anything about it), sometimes the best option is to harvest plants a little early to avoid further losses.

“When I had to throw away most of my plant due to bud rot, I cried a little, on the inside.”
~ Cannabis Grower

Table of Contents

What Does Cannabis Bud Rot Look Like?

What Causes Bud Rot?

• How does the Botrytis fungus get to my plants?

How Do I Control Bud Rot?

• Prevention
• Treatment
• Mold-Resistant Strains

What Does Bud Rot Look Like?

Usually, a bud rot infection becomes visible on just certain parts of your cannabis plants. Indoors, it’s often the bigger and denser buds that get affected first. Outdoors you may get patches all over the plant, even on smaller buds, especially after a few rainy days.

With bud rot, certain areas on the colas (buds, hairs and/or attached leaves) start dying, in stark contrast to the rest of the buds. The changes happen quickly, within just a day or two. Affected buds may appear strangely colorful, yellow, or brown. Buds often appear dried up.

The deadened spots usually stand out and catch people’s attention, even if growers don’t know what’s wrong, they often instinctively know that something is wrong since the spots don’t look like the rest of the buds on the plant.

In addition to the rot itself, you may see white or gray fuzzy mold on the outside of the bud. With advanced bud rot, the bud will easily separate so you can see inside. When a bud with bud rot is inspected, it will be dark gray or brown on the inside, and possibly dusty (this “dust” is fungus spores).

Depending on the life stage or particular species of mold/fungi, bud rot can look…

• white and fluffy

• dark gray or brown (sometimes even dark purple)

• the buds can be full of dark speckled dust which easily blows away (fungus spores)

“I lost half my plants last year to bud rot…  After a couple of drizzly days, I noticed spots, and then I saw that it had spread to all my plants.”
~ Cannabis Grower

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 🙁

Usually, the bud easily splits at the base of the sick leaves to reveal the rot inside. At this point, there was still white mold inside, but within a day it would have darkened and the inside would look brown or gray.

Another example of marijuana bud rot from afar… (it’s that brown dead patch on the bottom half)

And here’s that same bud rot up close.

What Causes Bud Rot?

Cannabis bud rot is caused by a type of fungus known as Botrytis cinerea. Sometimes you may get another type of fungus or mold that attacks the buds, but the cause, symptoms, and effects are usually similar.

In cannabis plants, Botrytis causes buds to rot out from the inside, hence the name “bud rot.” If you crack open an infected bud, the inside will be a moldy dark gray or brown.

Bud rot can cause different symptoms on different plants. For example, this cola (big main bud) responded to bud rot by turning purple and mushy. The leaves became crispy and started dying alongside the buds. This is what the grower came back to find after a few days of rain.

Did you know? In addition to cannabis bud rot, Botrytis causes problems for many different types of plants, including wine grapes, strawberries, and peonies.

The Botrytis fungus is sometimes referred to as “botrytis bunch rot,” “botrytis blight,” “bud rot,” “grey mould” or “gray mold.” When it comes to cannabis, it is often only called “Bud Rot” since that’s the main symptom cannabis growers are worried about.

Any part of the cannabis plant affected by bud rot should be discarded immediately! This helps prevent further infection and all buds touched by this toxic fungus should never be smoked or used.

Throw Away All Buds with Any Sign of Bud Rot! (brown is not a healthy bud color)

This is bud rot after the buds are broken apart. Not safe to consume.

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.

Luckily, healthy cannabis plants will usually not develop bud rot unless exposed to stagnant air and wet conditions or high humidity for an extended period of time. Your plants are also more susceptible to bud rot, fungus, or mold when the temperature is hot or cold. Aim for a temperature of 75°F (24°C) in the late flowering stage if possible (this also helps produce the highest quality buds).

How does the Botrytis fungus get to my plants?

Bud rot is spread to plants by dusty gray spores, usually in wind or water. If your plants are never exposed to these spores, they will never get bud rot.

Unfortunately, the spores can easily be carried to your plant by a breeze, rain, from contact with animals, or even by clones from another grow room. Indoors they may be floating around the air. Dormant spores can survive in many conditions only to affect your crops another time. It’s much more effective to try to prevent the conditions that allow bud rot to grow than to try to protect your buds from any contact with spores. That being said, infected buds can spread millions of spores and must be immediately and carefully moved away from your plants.

If you see rot like this, toss carefully so the rot can’t spread millions of spores over your other buds.

The fungus will never germinate if you keep buds in great environmental conditions. The spores are also more likely to take residence in your buds if there is some sort of “wound” on the plant. Possible wounds that can let Bud Rot fungus in include cracks in the stem from wind or over-training, damage from caterpillars, snails, worms, white powdery mildew, other pests, and larva. Any injury or weak point can be a good point of entry for bud rot spores into the plant.

Bud Rot needs wet or humid conditions to thrive. Even if your plant gets exposed to spores, you can usually prevent a bud rot infection by providing your cannabis with a moderate, dry, breezy environment (much easier indoors than outdoors).

What triggers spores to grow into a full-blown case of bud rot?

Wetness or High Humidity <– MOST IMPORTANT FACTOR, DON’T IGNORE THIS!

This is the most important factor. If you’re suffering from bud rot or mold, even if you remove the affected buds, it will likely keep spreading until you fix the humidity and keep buds dry.

• High humidity (above 55-60% RH) is the biggest contributor to mold growth and bud rot
• Leaves should not be touching each other creating wet spots (defoliate plants that are too bushy)
• Any situation where buds remain wet or in humid air for several continuous hours can be a trigger for bud rot
• Great air circulation in the grow space helps prevent any mold or fungus from growing

Outdoor

• Bud rot is often triggered by rainy or humid weather, especially if it lasts for days in a row
• If outdoor plants collect dew during the night or get rained on, consider shaking plants to remove as much moisture as possible
• Frost can also trigger bud rot because it creates wet spots when it melts

Cool Air Below 60°F (15°C) Can Trigger Bud Rot

• The Botrytis fungus thrives in the 50-60°F (10-15°C) temperature range. So if you have a bunch of cool, rainy days, it creates the absolute perfect home for Botrytus to grow.

Freezing Temperatures Can Trigger Bud Rot Outdoors

• When temperatures fall, you may see frost on your leaves. The freezing temperatures are hard on your plants already, and then when the frost melts it creates an ideal environment for spore germination of the Botrytis fungus on outdoor plants. It’s common to get bud rot outdoors if it’s hitting freezing temperatures (or close to it), and causes freeze/melt cycles. Protect plants from frost in the flowering stage if at all possible. If you do get frost and it melts, make sure to shake the plants to get rid of excess moisture on the leaves or buds (just like you would after dew or rain). If the weather is not going to improve, it may be a good idea to harvest now.

Heat Triggers Mold and Fungi When Combined with High Humidity

• Many different types of mold can strike thick buds with symptoms similar to Botrytis, and warm temperatures are ideal for most other relevant species of mold that cause bud rot. Every degree above 75°F or 24°C tends to increase the chance of many kinds of mold especially in high humidity (mold typically won’t grow below those temperatures indoors). Since botrytis can strike at lower temperatures, it’s recommended to aim for a medium of about for 70-75°F or 20-24°C if possible if it’s humid and you’re worried about bud rot or mold in the late flowering stage.

Bad Air circulation

• Stagnant air invites bud mold. The lack of wind or air circulation over the top, underneath, and/or through the inside of the plant, helps provide fungus and mold a good place to grow

• Leafy plants tend to collect water in between leaves and create humid pockets of air. This can cause wet spots and prevent air circulation through the plant, which also makes a good environment for mold or fungus.

“My fan could not circulate the air behind those colas. I thought it would be okay, but then I noticed super white fuzzy areas. Next thing I knew, half the colas had dead spots.”
~  Cannabis Grower

Big Fat Buds

• Massive colas have moist conditions on the inside which don’t get exposed to air. This makes them a prime target for Botrytis bud rot or other types of mold.

• It’s a cruel irony that you usually only get attacked by bud rot after producing lots of big buds. Bud rot has earned the moniker “Curse of the Successful Grower”.

Sick Plants

• Many types of stress, including bud rot, are more likely to hit your cannabis plant if it’s sick or suffering from nutrient deficiencies.

Certain strains are more susceptible than others to bud rot

• Some strains are very mold-resistant, while others have little defense.

• Here’s a list of a few mold-resistant strains

How to Control Bud Rot (these are most important!)

Focus on keeping the humidity under 50-55% (most important!) and give plants plenty of air movement in a moderate environment.

How to Prevent Bud Rot

These are the most important points to remember…

• Keep humidity under 50-55% RH (Most important!) – This is the most important thing you can do to prevent bud rot from growing. It’s extremely rare to see Botrytis in dry conditions. Learn how to control the humidity. If you don’t fix high humidity, the bud rot will likely keep spreading even after you’ve removed all the affected buds.

• Good air movement – Create good air circulation and make sure there’s always plenty of air moving over all the buds and leaves. Make sure your plants are getting access to cool, fresh air.

• Protect plants from heat/cold or big temperature swings – Controlling temperature and keeping the grow space from experiencing big temperature changes can go a long way. Aim for 75°F or 24°C when you’re worried about bud rot, and avoid letting plants get overly hot or cool.

• Avoid letting buds get exposed to wetness – Don’t allow buds to sit in damp or overly humid conditions for long. Protect your plants from rain and shake them if you notice they’re wet from rain or covered with dew.

• Remove all affected buds immediately – Carefully remove and discard any and all buds that have possibly been affected by bud rot. Don’t let any rot touch other parts of your plant. This helps prevent bud rot from spreading, but it’s not enough if you don’t take care of the environment. Remember, the spores are always around, and it’s just a matter of whether they get the right conditions to grow.

Other tips to help prevent bud rot…

Avoid plant wounds. Avoid injuring your plants, especially in the flowering stage. Don’t leave open wounds to seep out water and nutrients. Instead, cover any open injuries with tape or some other “cast” until the injury closes up. Avoid pests like caterpillars or broad mites which burrow inside the plant, and overall try to keep plants healthy. A healthy plant is much less susceptible to all kinds of infections.

Keep some space between big buds. Cramming a bunch of plants with a lot of buds in a small space can increase the chance of bud rot. Buds should never be touching each other. Try to make sure every big bud has a little “breathing room” to itself.

Defoliate leafy plants. Remove some leaves on excessively leafy plants to help lower the humidity and overall moisture levels within the plant and around the buds. This is most effective indoors in a small space where the plant is greatly raising the humidity, but it can also be helpful outdoors. Remove any leaves are touching each other creating wet spots between them, or any big leaves that are covering or touching bud sites. Your plant won’t “mind” if you only remove leaves from leafy areas.

Watch out for symptoms of bud rot. Watch plants closely for signs of bud rot in the late flowering stage, especially on large or dense buds, and especially after humid or wet weather. If you notice leaves dying in patches on your plants, don’t wait. Investigate immediately.

When growing outdoors…

Get a strain meant for your local climate. If you live in a place with short summers and gets humid or rainy early in the fall, don’t get a strain that was developed near the equator.

There are fast-flowering, mold-resistant cannabis strains that are designed for growing outdoors in more rainy climates. For example, many auto-flowering strains have quick lives; perfect for a short summer before the Autumn rain or frost.

A good outdoor strain for those worrying about bud rot might be Pineapple Express, an award-winning, mold-resistant strain that performs well outdoors. This strain is fast-flowering and ready to harvest only 50 days after it starts flowering.

Purple Punch Auto is a great outdoor auto-flowering choice. Just plant seeds after the last frost in the Spring, then harvest about 2 months later (long before the rainy season in many climates).

Purple Punch Auto is resistant to fungus like bud rot. This strain is quick to harvest and will grow in any climate that has (at least) 2 warm summer months before it starts getting cold or raining.

Breezy location – Try to put your plants in a grow spot with a breeze, but not too much wind. This can be tricky, and it may mean visiting the grow spot a few times before planting.

Protect your buds from rain. If you know there will be drizzly conditions, cover your plants with a tarp to protect them from most of the rain. Don’t put tarp directly on plants or you’ll hurt your buds. Install the tarp up above the plants, and make sure it’s held up by the center part, that makes it so rain runs off the sides of the tarp instead of collecting in the middle.

Shake plants. Some growers shake their plants on dewy mornings or after rain, so any water drops that form on the leaves don’t become breeding grounds for spores.

Fungicides, Neem Oil & Burning Sulfur

In the flowering stage, never use fungicides, spray affected buds with anything including Neem oil, or burn sulfur.

These common tactics are not effective at stopping bud rot and will make your buds taste, smell, and look terrible.

Some growers use fungicides made specifically for Botrytis in the vegetative stage. But when it comes to cannabis, fungicides can only be used as a preventative before any buds have formed.

If you already have bud rot and can’t fix your environment (which is the best way to kill Botrytis), I highly recommend cutting your losses and taking down the plant.

• Most fungicides are not effective for bud rot. If you do plant to spray plants, it’s recommended to get one that’s specifically been developed to combat Botrytis.

• Any treatments for Bud Rot should be applied in the vegetative stage as a preventative.

• 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

How to Stop Bud Rot from Spreading

The inside of a dense bud provides a great place for Bud Rot spores to grow, and that’s the main place you’ll find developed Bud Rot on cannabis plants. Once you’ve spotted bud rot, it’s important to act immediately.

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.

Never Spray Your Buds with Anything!

Bud Rot Removal

• Immediately remove all rotted parts and nearby areas. The only way to stop the spread is to remove all signs of mold from the plant, then move plants to a cool, dry area with a nice breeze.
• Be extremely careful not to let any rot touch any part of the rest of your plant.

What Happens Next?

You can either…

• harvest the cannabis plant now
• let it continue to ripen, but only if you fix the environment

If your plant has been affected by bud rot, it means they need less dampness and air that’s more dry. If you can improve the environment, you can allow the plant to continue ripening after you’ve removed the infected buds. However, if you don’t fix the environment it will usually come right back, sometimes even attacking other buds overnight.

Here’s how to fix the environment:

• add additional air circulation
• lower the humidity (50% RH or lower is optimal if you’ve already seen bud rot, otherwise 55% should be low enough to prevent it)
• defoliate leafy plants (remove leaves covering bud sites, through the middle of the plant, and any leaves that aren’t getting light anyway)
• prevent wet spots on plant

If you can’t fix the environment, I highly recommend you cut your losses and harvest plants early. If you know that it’s still going to be cool, humid, or wet for your plants, your goal is to prevent further buds from becoming infected. Buds harvested early are better than moldy buds.

Whenever you do harvest your healthy buds, be extremely careful during the drying process. Normally growers want to slow dry buds, but if you’re worried about mold it’s better to dry them with plenty of air circulation and movement.

Jump to…

Cannabis Temperature Tutorial

Controlling Humidity in the Grow Room

Air Circulation & Exhaust Tutorial

Other Cannabis Pests, Bugs & Viruses

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