Troubleshooting for Cannabis Growers

What is wrong with my cannabis plant?

One of the most common problems for new cannabis growers is not knowing what is wrong with their plants. There are many different things that can go wrong, from nutrient deficiencies to insect infestations, and it can be difficult to diagnose the problem without experience. However, there are a few basics that you can look for when trying to determine the health of your plants.

• Check the overall health of the plant. Are the leaves wilted, discolored, or distorted?
• Look for any pests or signs of damage caused by pests.
• Examine the roots of the plant. Are they healthy and white, or are they brown and rotting?
• Smell the soil. Does it smell earthy or like something is rotting?
  Feel the soil. Is it dry and crumbly, or wet and slimy?

What are common problems experienced by new growers?

There are a few common problems that new cannabis growers tend to experience, including nutrient deficiencies and toxicities, and environmental threats during your grow. We will break down each in detail below.

Nutrient Deficiencies

One of the most common issues that new growers have is not providing their plants with enough nutrients. This can cause a range of different problems, from slow growth to the yellowing or browning of leaves. Nutrient excesses can also be a problem that can cause the plant to burn and have brown tips and oftentimes the leaves will have an unusually dark green color among other conditions.
Click Here to Learn About Nutrient Deficiencies.

Environmental Threats

In addition to troubleshooting for problems that cannabis plants might have internally, you will want to troubleshoot your grow environment as well, specifically your watering schedule, temperature, and pest controls. It is important to make sure that your grow environment has enough airflow through the plant and not too much heat. You also want to make sure that your plants don’t get attacked by pests such as spider mites, powdery mildew, and fungus gnats although there are many more.
Pest threats can be difficult to troubleshoot because you might not always know what is attacking your plant at first glance. For more information on how to diagnose an environmental threat or pest infestation in your grow, please see our section on environmental threats below.
Click Here to Learn about Environmental Threats

Nutrient Deficiencies or Toxicity

How do I diagnose a nutrient deficiency or excess?

One of the most important things to know when troubleshooting cannabis plants is how to diagnose a nutrient deficiency or excess. This can be difficult without experience, but there are a few basics that you can look for.

For Nutrient Excesses

Look for signs of discoloration in the leaves, including wilting, browning, and a darker shade of green on the leaves. However, you will also want to look out for signs of nutrient burn, which includes plants that are pale or have big brown tips.
In addition to looking for these general signs of nutrient deficiencies and excesses, you can also take a soil sample to test the pH level and nutrient levels in your soil. This can be helpful in troubleshooting specific problems with your plants. For more information on how to take a soil sample, please see our article about using a soil slurry and how to PH your wate

What are the different types of nutrient deficiencies?

There are many different types of nutrient deficiencies that can affect cannabis plants, but some of the most common ones are: nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S).
Each of these deficiencies can cause a range of different symptoms, which makes troubleshooting difficult. However, there are some general things to look for when trying to determine the source of the problem.

Nitrogen Deficiency

Nitrogen deficiency is one of the most common nutrient deficiencies in cannabis plants and can cause leaves to turn yellow or pale while the veins remain green, which is called interveinal chlorosis. The leaves can also appear to have a lime green color. Nitrogen deficiency typically starts at the bottom of the plant and works its way up it.

Nitrogen Toxicity

Nitrogen toxicity is another common problem that new growers face. When cannabis plants are exposed to too much nitrogen, their leaves turn a very dark shade of green and the dark green coloring will move up the plant as it progresses.

Phosphorus Deficiency

Phosphorus deficiency is another common nutrient deficiency that causes trouble for cannabis plants. One of the first signs of phosphorus deficiencies is twisted dark bronze/brownish, or purple metallic-looking leaves near the bottom of the plant. As this deficiency progresses, it can cause dark purple or black blotches on leaves and the upper leaves may turn a bluish-green.

Phosphorus Toxicity

Phosphorus toxicity can also be a problem for cannabis plants and is caused by an excess of phosphorus. When this happens, the new leaves will have interveinal chlorosis with the leaf tips and edges displaying brown burn damage. The lower leaves will curl and some leaves may display signs of calcium or magnesium deficiencies.

Potassium Deficiency

K-deficiencies are another common nutrient problem that cannabis plants face and typically appear as a yellowing of the leaf tissue between veins that remain green (similar to nitrogen deficiency), but can also cause the entire leaf to turn yellow, which is also called chlorosis. This is especially true of the older leaves. The leaf margins or tips may also brown.

Potassium Toxicity

When cannabis plants are exposed to too much potassium, they can suffer from potassium toxicity, which is characterized by the lower leaves curling and developing spots that will eventually move up the plant. The new leaves will start to show interveinal chlorosis and have thin blades. Calcium and magnesium deficiencies can also develop.

Calcium Deficiency

If you have a calcium deficiency the lower leaves will contort and curl. Yellow or brown spots will develop on your leaf tips and margins and they will work their way up the plant. Your roots also may become black.

Calcium Toxicity

A calcium excess is normally characterized by your leaves wilting or appearing droopy and will also stunt your plant growth while causing a nutrient lockout.

Magnesium Deficiency

Another common nutrient deficiency that affects cannabis is magnesium (Mg) deficiency and it is characterized by the lower leaves drying, browning, and eventually falling off the plant. Interveinal chlorosis is possible also accompanied by random brown spots on the leaves.

Magnesium Toxicity

If your plant has magnesium toxicity it will display very dark green leaves. Your plant may also be stunted.

Sulfur Deficiency

A sulfur deficiency is characterized by new leaves being yellow or lime green. Purples streaks on the stem are also possible and leaf tips can burn, which means they will have a brown or bleached color and will turn down.

Sulfur Toxicity

When your plant has sulfur toxicity the plant leaves will be a darker green than normal. The overall growth will also be stunted and your leaf tips and margins will show signs of burn.

These are the most common deficiencies and excess. Please click on each deficiency or toxicity to learn more from articles detailing each one and how to fix them.

Environmental Threats

What environmental threats do my plants face?

There are typically two different general threats that face your plant when you are growing and they are your environmental factors like lighting and temperature and pests such as fungus gnats, spider mites, and bud rot. Below we will detail the most common problems for each.

Environmental Threats

Light Burn

The most common environmental factor that affects cannabis plants is light burn. This occurs when the plant is getting too much light and the leaves will start to turn yellow or brown and may eventually die. This is especially common for indoor cannabis cultivation. Read more >>

Heat Stress

Another problem that can occur from environmental factors is heat stress. When a cannabis plant gets too hot, it can cause the leaves to droop and the stalks to bend. The flowers will also start to wilt and may not form correctly.

Too Much or Too Little Humidity

Humidity can play a large part in your grow room. When there is too much humidity, you may notice fungal gnat infestations and bud rot along with the leaves drying up or drooping. If there is not enough humidity it will cause slow growth and yellowing of the lower fan leaves which eventually fall off if they don’t recover.

Over or Underwatering

Another environmental factor we will discuss is watering. Overwatering your cannabis can lead to root rot, while underwatering will cause the leaves to turn yellow and eventually fall off. Overwatering is the first problem most new cannabis growers encounter. To learn more about watering your cannabis plant check out our article here

Nutrient Lockout

When you give your plant too much of a nutrient or if the pH is off, it will cause a lockout. A lockout means that the plant can’t uptake any of the nutrients and this will show as deficiencies in different areas of the plant.

Windburn

If your plant is in a drafty area, it may receive windburn. This occurs when the air blows on the leaves and causes them to dry out or burn which can cause leaf damage that looks like heat stress (drooping/bending).

Pests

Powery Mildew

Powdery mildew is a common fungus that affects cannabis plants and it will cause a white powder to form on the leaves. The buds may also start to get covered in this powder.

Bud Rot

Bud rot or mold is another common pest that affects cannabis plants. It will usually show up as a fuzzy white substance on the leaves and buds, but can easily spread to other parts of your plant.

Fungus Gnats

One of the most common pests that growers face when growing cannabis is fungus gnats. These tiny black flies will lay their eggs in moist soil and the larvae will eat away at your roots. The adults can be seen flying around plants because they are attracted to light.

Spider Mites

Another pest that cannabis growers frequently encounter is spider mites which feed on plant sap causing damage by puncturing holes into leaves and buds, often hiding from view. They will also make a webbing on the plants that some people may mistake for spiders.

Are there any tips for diagnosing my plant’s problems?

Yes, definitely! When you are troubleshooting, it is important to take into account all of the factors that could be causing the issue. For environmental problems, you want to look at light burn, heat stress, humidity levels, and watering. For nutrient deficiencies and toxicity, you want to look at soil pH levels, watering practices, and any nutrient add-ons that you have been using.

You also want to consider pests and look at your plants for signs of powdery mildew, bud rot, fungus gnats, spider mites, or anything else out of the ordinary. If everything is going right but all your troubleshooting points are a ‘no’ then it could be a pH problem.

There are a few other troubleshooting points you should be aware of as well:

• The first sign of nutrient deficiency is usually the lower leaves turning yellow and dying off. If only one or two leaves on the plant turn yellow, it could also mean that there’s too much direct light hitting those specific parts of your plant.
• Wilting is a common sign of overwatering, while curling leaves may be a sign of underwatering. Brown spots on the leaves can indicate heat stress or too much light.

Summary

In this article, we troubleshoot some of the common problems new cannabis growers face. We discuss environmental threats such as overwatering, underwatering, windburn, and pests. Then we go over nutrient deficiencies and toxicity and how to diagnose them. Finally, we give a few tips on troubleshooting in general. As always, if you have any questions feel free to ask! If you would like to learn more about what might be troubling your plant please read our linked articles to each problem which will provide detailed answers on how to fix them. For further reading, please read our articles on nutrient lockout, temperature, PH’ing your water and runoff, and humidity, or check out our cannabis growing environments page to learn how to maintain the optimal environment for  your cannabis plant to thrive. Thanks for reading our article and happy growing!

I don’t always grow, but when I dor, I grow with bionics.
J.M.