Marijuana Foxtails

Despite being hardy by nature, cannabis plants are responsive to the environment they grow, meaning a double-edged sword for growers. 

On the one hand, they use the responsiveness of cannabis to increase its yield through plant training techniques and different growing methods. 

On the other, this means cannabis is more likely to respond to stress and poor environmental conditions.

And that’s what foxtail weed is, a sign for growers that their marijuana plants are stressed. 

However, there’s more to foxtailing than just stress. It could also indicate that genes or other factors relating to the environment impact the weed you grow.

Foxtailing on weed
Foxtailing on weed

What is foxtailing on weed?

Before we explain what causes foxtailing, we first need to know more about the formation of buds on cannabis. 

Typically, weed will begin developing its buds after six weeks of vegging or when you finally switch the light cycle from vegging to flowering.

The first sign that your plant is developing its buds is the white hairs that you see growing on the main stem, typically in the topmost part, referred to as the cola. 

It would take 2-5 weeks of flowering for your buds to fully mature from that point.

When grown in the best conditions, the colas of your cannabis plants will look heavy and dense

However, if your weed was under a lot of stress while flowering, there’s a high possibility that your plant will produce foxtail buds.

Furthermore, the odds increase depending on your strain’s genetics, as foxtailing is a trait found in some weed strains. 

Foxtail weed
Foxtail weed

What does foxtail weed look like?

Compared to regular buds, which are fat, dense, and cone-shaped, foxtailing cannabis has a long and slender appearance. 

The sugar leaves of foxtail weed buds are long and stretched, giving them a bushier look, which is where the condition gets its name.

Sativas and Foxtails

Although foxtail weed indicate a sign of stress for your cannabis plants; it could also be a natural trait. 

Foxtailing is a common genetic trait in many sativa strains, which generally means that they’re not a serious concern for growers.

You can tell if your sativas are foxtailing if their buds have a firm and spiky appearance.

What causes marijuana to foxtail?

Foxtailed marijuana
Foxtailed marijuana

Light Stress

In most cases, light stress causes foxtail weed. 

If your grow lights are too close to your cannabis plants during their flowering phase, it could lead to your plants’ colas elongating and producing the distinct spire-like shape that foxtailing cannabis has. 

This type of foxtailing typically has burnt or bleached tips due to the heat from grow lights.

Excessive Heat

When exposed to an excessive amount of heat, the buds of your cannabis plants will also foxtail. 

However, this type of foxtailing is distinct since it continuously causes your buds to produce pistils. 

While the increased number of pistils isn’t a cause for concern, it should be a warning sign that your plants are getting too much heat, leading to less potent buds.

Download my Grow Bible to start growing like a pro by learning how to deal with foxtailing.

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To safely prevent your plants from getting too much heat, you can follow this chart:

Stages Temperature
Seed germination 21-32°C
Seedling 20-25°C
Vegetation stage 22-28°C
Flowering stage 18-26°C

Poor Root Health

Soil and everything in it can also be a factor in foxtails. Weed is a responsive plant that reacts to changes in its environment. 

In particular, the area that’s most susceptible to these changes is the root system.

Stress brought about by poor soil conditions can cause a decline in root health and cause foxtailing buds.

Improper pH

The pH level in your soil is one of the few important factors for maintaining a healthy soil environment for your cannabis plants. 

The optimal pH level that your soil needs to be is between 6.0-7.0 since cannabis plants love slightly acidic growing mediums

And while slight fluctuations in your soil’s pH level aren’t a concern, if it continues to spike and drop, it can cause your roots to have difficulty absorbing nutrients from the soil, resulting in foxtail buds.

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Bad Microbes

While some beneficial fungi and bacteria help break down nutrients in your soil to something that your cannabis can absorb, there are harmful microbes that feed on and damage the roots of your plants

Harmful microbes like nematodes are parasites to cannabis since their primary food source is the contents inside of their roots. 

The stress of these microbes can cause foxtailing.


In some cases, cannabis just grows foxtails, an innate trait in some weed strains, particularly with sativas strains and, by extension, tropical strains

It was a trait to allow the buds to survive the hot and dry growing conditions they originated. It’s similar to how purpling and hermaphroditism occur in weed.

How to manage marijuana foxtailing

Marijuana foxtailing
Marijuana foxtailing


To avoid light-stressed foxtailing cannabis, you have to adjust the lights in your grow room in response to the growth of your plants. 

As your cannabis plants get taller, the distance between the colas and the lights closes in. 

By adjusting the elevation of your lights, you can maintain the minimum distance (25cm or about 10 inches) between them and the canopy of your plants.


Any grow room can suddenly spike in temperature during summer. 

Having a set of extra fans blowing on your plants and a proper ventilation system to cycle warm and cold air in your grow room can prevent this sudden heat rise. 

For outdoor-grown cannabis, you can put a shade cloth over your garden to protect them from the heat.


Monitoring your pH levels is necessary when growing cannabis. 

Like how you would monitor the humidity and temperature in your grow room to prevent heat stress, you would need to check the pH of your soil to prevent a nutrient lockout in your plants. Keep pH levels between 6.0-7.0


The best way to rid yourself of harmful microbes in your soil is to use microbes.

Introduce beneficial microbes such as rhizobacteria and mycorrhizal fungi into your potting soil. These will combat harmful microorganisms like nematodes.

Good vs Bad Foxtailing
Good vs Bad Foxtailing

Good vs Bad Foxtailing

Foxtailing either doesn’t affect your cannabis and its yield, or your buds lose potency, depending on what causes it. 

Whether it’s a bad thing depends on how the grower sees foxtail buds in general.

However, many people separate good foxtailing from bad foxtailing based on these guidelines: 

Good foxtailing

It means it was a product of genetics, meaning the grower knew and intended their strain to produce foxtail buds. 

It’s also important to understand that this type of foxtailing doesn’t affect the potency of the strains’ buds, and in some cases, it’s merely an aesthetic choice.

Bad foxtailing

It is caused by environmental stress. Typically they’re produced by weed strains that don’t usually grow foxtails. 

The harvested buds from these stressed plants will have lower potency, not to mention they would either have burnt tips or a high number of pistils (depending on the type of stress).

Foxtail weed
Foxtail weed


Foxtail weed is either a unique trait or a sign of stress with your plants. 

The best way to differentiate between the two is by knowing whether it’s a product of genetics or the environment. 

You can download my Grow Bible to start growing like a pro by learning how to deal with foxtailing and other cannabis plant problems.

If you want to avoid (bad) foxtailing entirely, the best way to do so is by growing cannabis strains that have strong genetics which resist foxtailing. 

You can buy high-quality seeds with strong genetics at

Happy Growing,


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