Cannabis Foxtails: What Happens to Your Crop?

Although every marijuana grower hopes that their plants have no issues during the growth cycle, things don’t always go according to plan.

Foxtailing is a prime example, but it doesn’t necessarily spell disaster for your crop. It is an occurrence typically associated with stressed plants and could reduce their overall yield, though you can still harvest such plants safely.

This article explains what cannabis foxtailing is, the issues it may cause, the reasons it can happen, and how to deal with the situation.

What Are Foxtails?

Typically, when you grow marijuana indoors, your plants begin developing their coveted buds when you adjust the light cycle to change from the vegetative stage to flowering.

The white hairs on the cola are the first sign of bud development. From that stage, flowering buds mature in two to five weeks.

If all goes well, your plants will boast dense, heavy colas. However, something could go awry, resulting in the development of foxtail buds.


You’ll notice such buds because they look long and slender, and their irregular shape draws your attention. Rather than the dense, rounded, and tight buds you want, you get tall and narrow ones. ‘Foxtail’ buds get their name because their sugar leaves are long and stretched out. This bushy look makes them appear like a fox’s tail.

If you see cannabis foxtails, you don’t necessarily need to panic. After all, it isn’t a sign of a sick or unhealthy plant. Indeed, the buds may still be relatively potent and resinous. Nonetheless, foxtailing buds do have the following downsides:

  • Lower Market Value: This isn’t of concern to home growers. Yet, if you plan to sell your weed commercially, foxtails are not ideal. Rightly or wrongly, foxtailing buds are perceived as a sign of lower-quality marijuana, which means you’ll fetch less money when selling it.
  • Reduced Yield: It’s fair to say that foxtailing buds are less dense than “standard” ones. Thus, they have less bud mass, resulting in a lower overall yield compared to plants laden with tightly packed buds.
  • Unusual Cannabinoid/Terpene Contents: Cannabis plants with foxtailing buds may taste and smell differently. That’s because the process potentially interferes with the buds’ terpene and cannabinoid production

It’s worth noting that some breeders deliberately try to create foxtailing buds. This is primarily because they look cool!

What Causes Marijuana Foxtails?

If your goal is to prevent foxtailing buds, you must learn all about the different factors that cause this phenomenon. The bad news is that it’s a multifaceted issue. However, we outline six possible reasons why it happens below.


Certain genetic traits increase the chances of foxtailing. Reputable seed sellers will indicate this when unveiling new products. While factors such as heat or light stress (which we discuss next) can result in foxtailing, when a strain is specifically cultivated for this purpose, it tends to have a more uniform appearance.

It is a genetic trait mainly found in sativa strains, particularly “heirloom strains” such as Durban Poison and Acapulco Gold.

High Temperature

Foxtailing can happen if your plants are exposed to an excessive level of heat. When growing marijuana indoors, you want the grow room temperature to be between 68 and 77 degrees Fahrenheit during the seedling phase. The range nudges up slightly to a maximum of 86 degrees during the vegetative stage and falls to about 80 degrees during flowering.

If your grow room goes beyond these maximum temperatures for long periods, you might see the formation of foxtailing buds. Beware the effects of heatwaves, which can cause significant temperature spikes indoors.

Light Stress

Your marijuana plants require light to grow. However, a common mistake made by growers is to overdo their grow lights. Some experts suggest that anything above 1,000 PPFD (Photosynthetic Photon Flux Density) is too intense for certain strains when you don’t supplement with CO2.

If you have high-powered LED lights, there’s always a risk of exposing your plants to light stress. Yellowing leaves is another sign that this is happening.

Problematic pH

In a very general sense, it’s wise to keep the soil’s pH in the 6.0 to 6.8 region, although the sweet spot has a smaller range. The pH when using a hydroponics or aeroponics setup is usually slightly lower, with the ideal range somewhere between 5.5 and 6.5.

When the pH is at the correct level, your plants’ roots should find it easy to uptake nutrients. However, get the pH wrong, and roots stop absorbing nutrients. The resulting stress could lead to foxtailing buds.

Microbe Damage

The pH isn’t the only important soil-related issue to consider. The soil you use houses millions of microbes, which generally form what’s known as a symbiotic relationship with the plants’ roots.

However, if the soil contains harmful microbes, such as parasitic nematodes, you face big problems. Nematodes like to munch through plant roots, resulting in serious damage, with yellowing leaves once again a warning sign. This is yet another form of stress that leads to foxtailing.

How to Handle Cannabis Foxtails

If you spot foxtailing buds, it’s time to act quickly if you want a positive outcome. As is always the case when dealing with marijuana plant problems, the sooner you spot the issue, the more you can do to fix it.


For instance, if you find foxtailing buds early on, when lots of smaller flowers haven’t yet bloomed, you can reduce stress levels and prevent the foxtails from fully forming. Here are a few tips:

  • Control the Temperature: Invest in a hygrometer to help you track the temperature and humidity in your marijuana grow room. If you see evidence of excessive heat, switch on the fans to reduce the temperature to a more pleasant level. If you grow marijuana outdoors, put a shade cloth over your plants if the temperature is blazing hot.
  • Test the pH: Buy a pH meter and calibrate it before measuring the pH of your growing medium. Keep it in the appropriate ranges and take a reading once a week. If the pH is too high or low, use pH Up or Down to tackle the problem.
  • Microbe Management: If you’re concerned about nematodes invading your soil, introduce beneficial microbes such as mycorrhizal fungi or rhizobacteria. These are excellent at warding off nematodes.
  • Level Off Your Lighting: Don’t keep your lights in the same place throughout the growing cycle. You must move them as your plants grow to ensure light stress doesn’t become an issue. If you notice crispy, yellowing leaves, it could be a sign that the plants are too close to the light source.

Fix Cannabis Foxtails & Enjoy A Bigger Yield

Certain breeders enjoy the unusual appearance of foxtailing buds. However, if you allow this issue to take hold, you may find that the amount of harvestable bud decreases. You can reduce the risk of foxtailing by minimizing plant stress.

This means maintaining a comfortable grow room temperature, ensuring the pH is at the right level, and checking the soil for harmful microbes. It’s also important to avoid placing your lights too close to the plants, and you may want to veer away from certain sativa strains if you’re keen to lower the risk of foxtailing.

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