White Spots On Cannabis Leaves? This Might Be The Cause!

White spots on cannabis leaves indicate that your crop is in trouble.

However, there are several reasons why white spots appear on weed leaves.

It can be due to spider mites, thrips, powdery mildew spores, and many more.

If not treated on time, these issues can lead to infestation and may even kill your plant.

So, how can you avoid that? Worry not!

Today, we’ll explore why your weed plants have white spots, their causes, and the solutions you can apply to eliminate them ASAP.

Let’s get into it, shall we?

What Causes White Spots on Your Cannabis Leaves?


Thrips, spider mites, and powdery mildew are the primary reasons for white spots on weed leaves.

However, to find out precisely the reason for your specific case, you must look out.

And as quickly as you identify, you can go for the solution to save your baby crops.

Here is a detailed overview of the causes of white spots on cannabis leaves:

1. Fungal Diseases

When you grow cannabis plants, you should know weeds are usually susceptible to fungal diseases.

These pathogens can spread quickly throughout the plants to destroy them.

One of the infamous fungal diseases is the white powdery mildew, on cannabis that represents white spots on the leaves.

  • Powdery Mildew

Powdery mildew is a fungus with surface-level fuzzy texture growth you can see on the plant leaves.

The powdery mildew is quite a common issue in cannabis plants.

Powdery Mildew On Grown Cannabis Plant

It attacks the foliage of leaves and disturbs the plant’s photosynthesis ability.

In the early stages of infection, you can observe small white spots on the leaves.

However, you need to identify the problem and stop the infection quickly.

It is because if it spreads, it can ultimately damage your crop.

The sign of severe powdery mildew is when you observe your leaf being covered with white fuzz.

The leading cause of the powdery mildew is the climate, especially in cool and humid conditions.

Also, fungus affects the lower leaves mainly, but mildew infection can present on any part of your cannabis plants.

However, one of the other things that may cause this issue is the use of cannabis fertilizer excessively.

Even though the fertilizers speed up the plant’s growth, their excessive use can make it susceptible to fungal diseases.

The only good part of powdery mildew disease is that it can be identified quickly, and thus, the issue can be solved quickly.

2. Pests

Several pests destroy cannabis plants.

Spider mites and thrips are some of the most common pest issues in weed; therefore, we’ll discuss them along with the other pest issues in detail.

  • Thrips

Thrips are one of the common pests that can cause white spots on cannabis leaves.

These are the tiny and thin insects that appear yellowish-white with elongated bodies.

The lopsided mouth part belongs to the Thysanoptera order and is up to one mm long in size.

Thrips even have wings, which makes them fly from one plant to another.

These insects eat the leaves of the marijuana plants and thrive on them while they draw out the essence of the leaves, leaving a sheen stain (slight silvery) on the cannabis leaves.

These thrips make cannabis leaves weaker with nutrients, while female thrips even lay their eggs there, increasing the infestation.

Thrips are among the most common indoor marijuana problems, and these insects reproduce fast.

So, they must be treated in time.

  • Spider Mites

Spider mites also cause white spots on fan leaves of the cannabis plants.

These tiny insects appear on the plant leaves in red, black, yellow, and brown dots.

There are around 1200 species, but these belong to the Tetranychidae family, acari, or mites subclass.

Spider mites are common pests that thrive on the cannabis plant leaves and make white spots appear.

A Close Up Image Of Spider Mite

These little insects pierce the leaves cells and feed on them.

If you observe white spots, it might be an alarming sign that your crops are in trouble, and they must be treated quickly before these insects damage the plants entirely.

These nasty insects spread out quickly if not treated in time, so frequent checks for the plants are necessary.

Spider mites can easily be spotted on the edge of the branches or under the leaves.

These tiny insects guard their little webs that might look like sliver dots. Even mites may also appear like white dots on the plants.

You can also check the presence of eggs or web underside the cannabis leaves, and if there are eggs, it is a clear sign that your plants might have spider mites.

Another key factor that makes spider mites thrive is the hot and dry climate conditions; they even reproduce quickly.

  • Fungus Gnats

Another common pest problem in cannabis plants is fungus gnats.

These pests are also harmful to the plants and may be the reason for white spots on cannabis leaves.

The appearance of the fungus gnats is like dark flies that look like gnats and are small in size.

These pesky insects belong to the family of Superfamily Sciaroidia.

The larvae of the insects feed on the plant roots, which affects the young cannabis plants grow up’ ability to absorb water and nutrients.

Moreover, these insects also damage roots and ultimately hinder plant growth as these fungus gnats live in the soil.

Therefore, when the cannabis plant is in the seedling stage or young condition, these issues can damage it.

Hence, you are recommended to check out for the issues of it regularly.

As these insects live in the soil, you might have to look for the symptoms of the plants as you can not identify them on the plant leaves like other bugs.

What Can Happen If You Ignore White Spots On Cannabis Leaves?

Before I talk about the solutions, you should be aware of the problems that these insects might cause.

It doesn’t matter which insect issue occurs in your plant. If it is not treated on time, it may lead to the ultimate decrease in the crop quality and quantity, which you, as a grower, never want.

Therefore, a good cannabis growing habit is regularly checking for plant health.

Ignoring Plant Health Issues May Lead To Severe Bug Infestation

If white spots are ignored on the cannabis leaves, then it might lead to:

  • Severe bug infestation
  • Decrease in plant growth
  • Decrease in the bud production from the plants

You are growing weed plants for the weed plant buds. Right?

If, during the growth stages, your plants have a bug infestation, then it might lead to the issues mentioned above, which you should always prevent.

3 Step Solution For White Spots On Cannabis Leaves

As you already know about the possible causes for white spots on cannabis leaves and what can happen if you ignore the issue, it is an excellent time to dive deep into finding a solution to prevent that.

To spot and stop white spots on cannabis leaves, these are the possible solutions that one may try.

However, we recommend identifying your specific infestation or problem type first before you can apply the solution accordingly.

Step 1: Identify

White spots on cannabis leaves may be for multiple reasons.

Therefore, it is necessary to identify your plants’ problems first.

Identify The Plant Issue Before Jumping To The Solution

For instance, if you believe spider mites are the reason for white spots on weed plants, you can identify them by looking for spider mites underside the leaves.

As these tiny insects hide under the leaves, you can easily find them and apply the solution accordingly.

Also, with identifying the exact reason, you have to check for the infestation stage.

If the infestation is starting, then the solution can also be light.

But if the infestation is severe, you might need to apply a solution more frequently to eliminate the problem.

Step 2: Solution

Once you have identified what causes white spots on cannabis plants, you can start with the solution step.

Here are the proven methods by growers that have prevented the white spots on cannabis leaves.

1. Prevention

The best way to avoid bug infestation is to clean and tidy your growing area.

It will also protect the weed and flower buds from dust as well as from the bugs.

You can frequently collect dead leaves or other plant matter from your growing space to practice garden cleanliness.

Ensure no dog, cat, rabbit, or other pets are kept in the grow space.

Keep the dead plant matter out of your grow room.

Most of the bug infestation in plants happens due to uncleanliness.

By keeping your grow area clean, you can make sure at least one of the factors for bug infestation is prevented.

Once you take the first step of cleanliness, the next step is to keep a healthy grow environment in your grow area.

You can do so by keeping an excellent airflow in your room, as spider mites thrive in stagnant air, which you can avoid by maintaining an excellent airflow.

It will not only help the pests keep away from your plants, but your plants will love it, too.

For prevention, you can even sprinkle Diatomaceous Earth on top of your plant soil, which works as a natural remedy and is safe for plants and humans.

2. Pruning The Leaves

Any cannabis infestation problem in one plant can also cause the infestation to rise in the other plants.

Therefore, if your entire cannabis plant, is having severe infestation, then one of the ways to prevent infestation in the other plants is to prune off the infested leaves.

You can prune off the leaves and stems of the infested plant to get rid of the bug infestation and save the other plants.  

3. Using Neem Oil

One proven way to stop white spots on cannabis leaves is by spreading neem oil.

The neem oil affects the bugs’ nervous system and kills them, ultimately leading to the cleaning of bugs from the cannabis plants.

For spider mites’ case, you might have to take an additional step to remove the web of the bugs.

It is because the spider mites build their web like a canopy and may survive the spray.

Apart from this, you can also use the Diatomaceous earth, which is also helpful in slowing the infection.

You can use the powder on the leaves, and the mites will die.

The best part about neem oil is that no harmful components might affect the weed buds.

4. Treating Grow Area With Insecticides

Although we don’t recommend using insecticide as your first step towards stopping white spots on cannabis leaves.

However, if you have already tried all the natural and simple ways to eliminate the problem you are facing, then one of the methods is to use insecticide in the whole growing space.

(Try to avoid this step and try the other methods first.)

Note: Many growers avoid the chemical sprays as it contains chemicals that are harmful to humans. Therefore, when choosing an insecticide, look carefully for the ingredients, read the instructions carefully, and go through warnings (if any) and the quantity to use. Try to use natural insecticides first and avoid the chemical ones.

Step 3: Prevent White Spots on Your Cannabis Plants

Once you eliminate the insects and pests’ issues, you must keep control of your growth environment so they don’t return to your plants.

Take prevention steps to avoid the causes that produce insects, such as cleaning (that I mentioned earlier).

Ensure to keep good airflow, high humidity under control, and heat in a normal range so that bugs don’t get any factors to thrive.

Also, if you have visited another grow room or space, try to check your plants after changing clothes, as you don’t want to bring insects or mites to your plants.

If you find any single plant having spider mites or bug infestation, then ideally, you should take that one infected plant out so that the other plants remain safe.

Treat that single plant separately and involve them with the other plants.

How To Get Rid Of White Spots On Weed Leaves?

The best way to eliminate white spots on cannabis leaves is to take prevention steps to avoid bug infestation and other issues.

For example, you must regularly check for any plant health issues as well as for the cleanliness of the garden.

However, if you observe any problem with the plants, then you must first identify the problem.

The above guide lets you quickly identify if your cannabis plants have spider mites, thrips, or powdery mildew issues.

You can easily approach the solution once you know about the specific plant problem.

Depending upon the infestation stage, you can apply the solution accordingly.

Sometimes, you might even have to do the solution twice or thrice a week (depending on the infestation).

Once you have eliminated the infestation and bug problem, you can keep checking on the remaining plants so that the infestation doesn’t happen again.

FAQs About White Spots On Cannabis Leaves

What is the white stuff on my cannabis leaves?

The white stuff on cannabis leaves may be due to bug infestation or fungus issues.

One of the primary reasons for the white spots on cannabis leaves is spider mites, thrips, or fungus gnats.

You can quickly get rid of the white stuff from cannabis leaves by applying the solution accordingly to the infestation you identify.

What are the white spots on my cannabis leaves, not powdery mildew?

If you have observed white spots on cannabis leaves and are sure they are not powdery mildew, then it might be the spider mites or thrips.

These pesky insects suck out the nutrients from the leaves and create a white spot there, which is why you are observing them.

However, to eliminate them, you can identify the specific infestation problem and then apply the solution.

What nutrient deficiency causes white spots on leaves?

Nutrients are the required components that keep plants growing. And if they lack any nutrients such as nitrogen, phosphorus, or potassium, they may also develop white spots.

How do you recognize fungus gnats?

One of the methods to identify fungus gnats is through their appearance. These tiny insects are grey to black and have slender legs and segmented antennae.

These are the appearance quality that helps you recognize fungus gnats from the related shore fly.

One of the other qualities is the Y-shaped vein in the wings, which makes them easily distinguishable.

Conclusion: How To Prevent White Spots On Cannabis Leaves?

Prevention is better than cure.

Therefore, to prevent white spots on young cannabis plants and leaves, you must practice good cleanliness habits in your growing area.

You can keep the dead plant matter in the trash bin so there are fewer chances of bug infestation.

Also, maintain a good and healthy growing environment for your weed plants by keeping humidity and temperature in control with excellent airflow of fresh air.

However, still, if you face any bug infestation or fungus issue, then there are several methods by which you can eliminate them.

Christopher Andrews
I am Christopher Andrew, the owner of 420 Expert Adviser. I have been in cannabis cultivation for more than ten years, and I'm sharing my experience with you guys using this blog!

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