7 Most Common Cannabis Problems

Over the course of your grow, you’re going to face lots of challenges with your marijuana plants.

And one of the biggest and most annoying ones is facing pests and other annoying problems with your marijuana trees.

Unfortunately, it’s part of the deal, but the good news is you can minimize these problems to achieve better going.

So what exactly are some of the most common cannabis problems?

Deficiencies in nutrients, spider mites and other pest infestations, mold, heat stress, light burn, and root rot are some of the most common issues you will encounter when growing cannabis.

The good news is that there are ways in which you can combat and prevent these problems from occurring in your marijuana garden.

So let’s take a closer at the most common marijuana plant problems and exactly how you can avoid them.

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7 Most Common Marijuana Plant Problems

#1 Nitrogen Deficiency

Marijuana Nitrogen Deficiency

If you’ve noticed that the older or lower leaves on your cannabis plant are yellow, wilting, and eventually falling off, then your plant probably has a nitrogen deficiency.

In this case, the plant would appear lime or pale in color. The yellow leaves may also show signs of brown and will become soft and fold in. Ultimately, they die and fall off.

These plants are usually pale-colored.

In some cases, they may not have obvious markings or spots when a nitrogen deficiency is present; however, you will notice that the entire plant is overall a lime green color.


This is a sign that nitrogen is lacking in your marijuana plants. Alternatively, your plant getting too much nitrogen will be much darker in color.

Nitrogen is known as a mobile nutrient, and ultimately this means that it moves throughout the plant as necessary.

Finally, your marijuana plant needs nitrogen so that it can stay green and make energy from the light.

New leaves get plenty of nitrogen to make them green and healthy via photosynthesis.

Ultimately, the fact is fresh leaves get priority over older ones, and if you are not getting the required amount of nitrogen, they will steal it from the older ones.

And ultimately this is what causes the yellowing and wilting in the older leaves.


Okay, so the solution to this problem is to find premixed nutrients that you can buy from the store.

Most of these premixes contain nitrogen or use nitrate of soda and sometimes organic fertilizer, which are both excellent sources of nitrogen.

The truth is almost all plant nutrients of various kinds would include nitrogen.

So if you’ve been providing your marijuana plants and high-quality nutrients, try supplementing the natural nutrients with more nitrogen and see if you can’t start the recovery process.

If your leaves are tiny near harvest time, then don’t panic; it is 100% normal.

#2 Spider Mite Infestation

Spider Mite Infestation

Spider mites are tiny pests that have the ability to breed very easily. Inevitably they can destroy a marijuana plant in a short space of time.

So if you suspect that you have an infestation, the best you can do is act quickly. Please don’t waste any time and go straight to getting rid of the problem.


Spider mites can enter your home, your marijuana plants, and just about any space pretty easily.

Because they are so small and travel in the air, getting around is a breeze.

For more information on exactly how you can get a spider mite infestation in your home, take a look at our previous post, which will explain the causes, effects, and ways to get rid of spider mites in your home.


Getting rid of spiders can prove to be a challenge if you don’t know exactly how to do it.

Perhaps the worst part is that they lay eggs on the underside of the leaves, and this can often be hard to get to.

The biggest pests are the female spider mites, and in order to reduce the number of eggs being laid, you have to kill the female’s first.

So ultimately they’ll be the main target.

Before you begin the process of eliminating the spider mites, you need to move your plants from the grow room.

It will need to be cleaned and disinfected while your plants are outside.

Ultimately the logic behind this is that it’s pointless to bring your plants back into a grow room that is not 100% bug-free.

Spider mites can be killed using homemade remedies such as homemade neem oil pesticides, which are organic yet still effective.

You can also use pyrethrin pesticides or use other predatory bugs to kill spider mites.

One of the bugs that you can try introducing is ladybirds.

To avoid another infestation, make sure your grow room is always clean and sanitized and free of any pests.

#3 Overwatering

Signs of Overwatering Plant

Water is good for your plants but in moderation. Excessive amounts of water can prove detrimental to your plant’s health.

Signs of overwatering include firm leaves that are curled down. In some cases, they may also be yellow in color, and this process is called chlorosis.

Overwatered cannabis plants are droopy. As a result of overwatering, they turn yellow and show signs of nutrient deficiencies as well.

However, this doesn’t always mean that overwatering is caused by literally giving your pants too much water.

It may also mean that you have been giving your marijuana plants the right amount of water but a little bit too often.

Alternatively, using a growing medium that tends to retain water, without giving the soil enough air is another problem that leads to overwatered plants.


  • Watering your plants too often
  • Giving plants too much water each time
  • Using water retention mediums to grow your marijuana in
  • Mediums not having enough air circulation


So one of the best things that you can do is to give your marijuana plants enough time between watering.

Also, ensure that the water is able to drain out of the bottom of the pots that you’re growing marijuana in.

Also, be very careful about placing small plants in extra-large containers.

Ultimately there is a proper way to water your cannabis, and this is how you should go about doing it:

  • Insert your finger up to the first knuckle into the medium to ensure that it is dry
  • Add water until you notice 20% of the water running out through the bottom drainage
  • Repeat step one
  • If you notice that the top of the medium is still wet for quite a long period of time, use less water on your plants or improve drainage.
  • Ultimately, the goal is to water your plants every 2 to 3 days.

#4 Underwatering

Symptoms of Underwatered Plant

Underwatering is another common problem when it comes to marijuana growing.

When your plants are underwatered, you will notice that they’re drooping.

They also have a thin papery texture as there’s not enough water inside them.

This is as opposed to overwatering your plants where the leaves are bloated and fat because there’s too much water contained inside.

However, the reality is that chronic under watering would eventually lead to yellowing leaves and nutrient deficiencies in your cannabis.

If a medium looks extremely dry every time you water it, you know that your plants are not getting enough water.


  • The plant is not getting enough water
  • The plant is not being wanted to frequently
  • The plant may have overgrown its pot and needs to be transplanted.


If you suspect that your plants are being underwatered, then don’t wait until the leaf starts to droop to start watering your plants.

Water it immediately.

In most cases, to be absolutely sure your plants are under-watered notice that the leaves are drooping and once you water your cannabis plant, notice that the leaves are immediately perky.

So some of the best ways to properly water your plants are to wait until the plant needs water, wait until you get a little runoff, and then insert your finger into the medium up till your knuckle to make sure that the soil is dry after watering.

Another great way to tell if your plant needs water is to pick up the pot itself.

If the pot feels light, this means that there is no water in your soil, and it needs to be wanted.

#5 Root Rot

Marijuana Sick Root

Usually, when your plant has root rot, you’ll notice that the leaves are curled and drooping and usually have an unhealthy appearance.

This is because they are not getting enough oxygen from the roots. Often the symptoms of root rot shot appear like a soil-plant that has been over or underwatered.


The root rot can be caused by several different types of organisms.

Some of these organisms include fungi, bacteria, algae, and parasitic oomycetes.

The symptoms are similar between each type of organism; however, they don’t always look exactly the same.

In most cases, common triggers are light leaks, heat as well as the lack of oxygen inside the water.


  • One of the things you can do to combat root rot is to treat the plant root directly. Alternatively, you can choose to change of plants environment
  • Also, add beneficial bacteria
  • Prevent any light leaks inside the reservoir
  • Keep the grow room cool
  • Avoid disturbing your roots especially while they are still young
  • Keep your grow area clean and sterile

#6 White Powdery Mildew

Marijuana Plant Powdery Mildew

If you notice white spots on your leaves that look more or round, patches of powder, then you probably have a major problem.

This white powder is not a major annoyance; however and it and can easily be fixed.

But, you need to catch it before it turns into a catastrophe and ruins your entire harvest.


Some of the causes of white powdery mildew include high humidity.

This is usually a problem for young cannabis because it needs relatively high levels of humidity in order to grow healthy.

However, high humidity is only a problem if it is combined with no airflow.

So mildew will only settle in an area where the air is not circulating.

So if you have high humidity combined with no airflow, this is the ideal breeding ground for white powdery mildew.

Poor ventilation is another major cause of mildew since it will multiply when there is no ventilation and eventually land on your plants and reproduce.

So if you’re growing cannabis in a closed area, ensure that there are enough insulation and fresh air circulating inside.

Leaves that touch each other retain moisture between them and become more likely to develop mildew.


If you can catch mildew early enough and can get to it if it’s quite silly.

You can use a combination of homemade concoctions as well as stop what products to the original marijuana plants up part of the mojo.

Some of the homemade remedies include smoke and water mixtures, baking soda and water mixtures, neem oil and water, hydrogen peroxide.

#7 Windburn

Windburned Leaves

If you are growing your cannabis indoors, then you’re likely using a fan to blow air around it.

Although cannabis plants love a nice breezy environment, sometimes it can be too much.

Too much wind can eventually cause clawed leaves that sometimes develop spots. This condition is called windburn.

So when they droop down, they form claws, and the drooping may look like a result of nitrogen deficiency.

Ultimately though, they have windburn, and this is when they are getting too much of a breeze.

Too much wind can cause unusual problems on the affected leaves such as bronze or brown spots that look like burn marks.


  • Too much wind


  • When using a fan, there should be a nice breeze surrounding the main canopy, so ideally, you’d want plants getting a gentle breeze flowing over and under the plans. The leaves should be gently rustling; however, they should never be waving around.
  • A strong fan should never be pointed directly at the plant because too much wind can damage the plants and leaves. If you have a very small grow area or room, then you should point the fan at the wall instead of directly at the plants; just ensure that all parts of the plant are getting a slight breeze.
  • It is recommended that you use a small oscillating fan in the growing area as it provides a gentle breeze and doesn’t blow in one spot for too long.

Related Questions

Are Cannabis Problems Easy To Get Rid Of?

It is, provided you detect the issues early enough.

Should You Use Homemade Remedies Or Store-Bought Solutions To Combat Cannabis Problems?

It is entirely up to you. Some home remedies may work, however, in some instances commercial treatments are more effective. So always do your research.

Are Marijuana Problems Common?

Yes, when growing cannabis indoors or outdoors expects challenges.

James Alexander James Alexander
Hey, I'm James! The founder and head writer here at GreenBudGuru.com. I started this site to share my passion and knowledge of all things cannabis. I used to work as a budtender in central Amsterdam, and have over 7 years of growing experience.

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