What Is Cannabis Foxtailing And What Causes It?

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What Is Cannabis Foxtailing And What Causes It?

Cannabis foxtailing is a phenomenon in which the buds of a cannabis plant start growing abnormal spires or tips. Read on for an overview of foxtailing, what causes it, and how it can affect your overall harvest.

Whether you’re a rookie grower or a veteran, chances are you’ve heard of foxtailing. But what exactly causes those iconic fox tails to form on your buds? In this article, we take an in-depth look at cannabis foxtailing, its causes, and what you can do to prevent and treat foxtailing in your plants.


Foxtails are a kind of aesthetic deformity we see in cannabis plants. Cannabis flowers, or buds, are formed by a bunch of unfertilized calyces. If pollinated by a male, each one of these calyces could house a seed. When left unfertilized, however, these calyces swell up and eventually form the buds we know and love.

In a normal cannabis bud, these calyces grow close to each other, around the branches of the plant to form round, even nuggets. Foxtails, on the other hand, form when these calyces grow unevenly on top of one another, creating a lop-sided, uneven looking flower.

Cannabis foxtailed calyces


Foxtailing can be caused either by genetics or by stress. If you’re growing outdoors, any foxtailing is almost always due to genetics. Some strains of cannabis are simply more prone to developing foxtails.

Indoors, however, foxtailing can be caused by light stress during the flowering phase. In this case, plants start developing foxtails in parts of the flowers that are too close to the light source for too long. This is most common in setups with HPS or plasma lighting. Plants with this kind of foxtailing usually also have bleached or burnt tips or buds as a result of the heat from the grow light.


This question is a little complicated. Technically, foxtailing doesn’t affect your buds in a negative way, other than making them look a little odd. However, it’s basically an aesthetic question and some growers even like the look of foxtailing. Others claim that a little foxtailing can help increase your yields, which is always positive.

Unfortunately, some foxtails can get out of hand and form big, long towers on the tip of a flower. While this kind of foxtailing is rare, it can throw off the even distribution of light across the rest of your flowers. This can ultimately affect the flower’s ability to grow and mature properly and may drive down your overall yield.


There’s not a lot you can do to prevent foxtailing. If you’re growing indoors, you need to closely monitor your plants and avoid having them too close to the lights. As most cases of outdoor foxtailing are caused by genetics, there’s literally nothing you can do to prevent foxtailing in your outdoor plants, except avoid strains that are more prone to this phenomenon.

If you start to notice signs of foxtailing on your indoor plants, the first thing you should do is move them further away from the light. Unfortunately, the heat and light stress that causes foxtailing indoors may also cause your buds to lose potency and decrease your overall yield. Hence, always keep a close eye on your plants and act quickly at the first signs of foxtailing to minimize any damage to your buds from the excess heat/light.