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cannabis leaf problems

Common cannabis leaf problems and how to fix them

While growing weed, you’re bound to experience a hiccup or two before harvest. That doesn’t always mean that you’re not giving your herbs enough love and care. 

Cannabis leaf problems range from internal complications to external ones like leaf problems.

When you notice an issue with your marijuana leaves, act fast to prevent more damage. Below are a few common cannabis leaf issues you might face and their easy solutions. 

Now, let’s get this show on the road!

Signs of dying leaves

The first step in solving weed leaf problems is identifying what they mean. Unhealthy leaves are easy to spot with a little attentiveness. 

Your plants send a signal that they’re struggling so that you save them before it’s too late.

Here are some cannabis leaf symptoms to observe:

  • Discoloration—brown, bronze, yellow, pink, purple, or blue-green. May appear as spots, patches, and at the tips or edges of the leaf.
  • They start to twist or curl.
  • Drooping or bending.
  • White/grayish powder or dust.
  • A full leaf may darken altogether.

cannabis leaf problems

Cannabis leaf problems and their solutions

You may encounter various causes for weed leaf problems like:

Let’s look at a few conditions to help you make the proper marijuana leaf diagnosis:

pH imbalances

pH is the measure of how acidic or basic something is. Weed grows best in slightly acidic soil of the range 6–6.9. For hydroponics, it’s a little higher at 5.5–6.5.

The wrong pH level is one of the main causes of cannabis leaf problems. It should be the first thing to check whenever there’s trouble. 

A pH imbalance prevents nutrient and mineral intake in the plants.  It consequently leads to different weed deficiencies, causing further damage.

If the test reveals an imbalance, store-bought products help in making adjustments. 

Natural methods like using baking powder, water, vinegar, or lime work as well. The marijuana leaf symptoms disappear a little while after the change.

Water, fertilizers, and boosters affect the pH level, so keep a testing kit handy. Mix and test the solutions before giving them to your plants to lower the chances of an imbalance. 

Allow the pH to move within the required range because cannabis absorbs different nutrients at different points.

cannabis leaf problems

Watering problems

A crucial factor to remember, especially for soil cultivators, is that how you water weed can also cause cannabis leaf issues.


Growers often overestimate how much water plants need—too much could destroy the air pockets in the roots, thereby reducing oxygen and suffocating them.

Marijuana leaf symptoms that come from overwatering include:

  • Drooping
  • The whole leaflet curls or bends downwards
  • Yellow discoloration
  • The leaves feel plump and rigid due to the excess water in their system

To solve and prevent these weed leaf problems:

  • Test the soil’s wetness by putting a finger an inch deep. If it’s still muddy or sluggish, give your herb a break.
  • Increase the time interval between watering sessions, or reduce the amount of water per session.
  • Ensure your medium has proper drainage—20% of the water should flow out.
  • Mix in pebbles, gravel, or sand to encourage proper air circulation if your soil is heavy.


Growth slows down when your weed doesn’t get enough water. 

All the cannabis leaf symptoms from overwatering apply here, except one. Instead of being rigid and succulent, the leaves look paper-thin and weak.

To take care of underwatering:

  • Test the soil’s dryness using your finger. Extreme dryness suggests it’s time for a drink.
  • Reduce the time interval between the watering sessions, or increase the amount of water you provide.

Nutrient problems

Living things need nutrients to grow healthy, and cannabis is no exception. A lack of nutrients like copper, potassium, and iron—or if there’s a problem with intake—may compromise your harvest.

Here are a few nute troubles that cause marijuana leaf problems:

cannabis leaf problems

Nutrient lockout

A nutrient lockout is when marijuana roots are unable to absorb any more nutes. It’s brought about by a pH imbalance or excessively using strong chemical fertilizes  

If the problem persists, it can cause more issues like cannabis iron deficiency. Note that not providing your weed with necessary nutrients and minerals brings about marijuana deficiencies as well.

Symptoms of a nutrient lockout include cannabis leaf discoloration, curling, darkening and stunted growth.

To treat it:

  • Stop providing nutrients.
  • Test and adjust the pH range appropriately.
  • Flood your growth medium with distilled water to flush out the excess chemical fertilizers. Give your herbs some time before feeding them more nutrients.

Use organic fertilizers, and check the pH regularly to prevent a lockout in the long run.

Nutrient toxicity

In the excitement of growing your herbs, you might find yourself overfeeding them. Then you’re left stumped, wondering why you have weed leaf problems.

Also known as nute burn, this occurs when you excessively provide nutrients or if they’re too strong. Symptoms include curled brown tips that feel dry and crispy or look burnt.

To fix it, simply stop feeding your baby for about two weeks. A cannabis leaf symptoms chart helps you identify the exact nutrient that’s causing toxicity so that you can reduce its quantity.

Light burn

Cannabis light burn, otherwise called light stress, occurs when we expose indoor weed to too much grow light.

You’ll likely face marijuana leaf problems such as:

  • Inward folding of edges and tips
  • Yellow leaves from the ones closest to the light, spreading down

Move the plants further from the lights to treat the light burn. If that’s impossible, move the lights higher, or reduce the number of bulbs. The cannabis leaf symptoms should disappear in a week or two.

To prevent it altogether, incorporate Low-Stress Training to grow short and thick marijuana instead of tall and thin.

Spider mites

One tough cannabis leaf problem is the spider mite. They’re very small orange, red, brown, or pale pests found on the underside of the leaves. 

These little devils rapidly reproduce, are hard to notice, and difficult to get rid of—any growers’ worst nightmare.

Signs of an invasion include tiny bite marks resembling tiny dots or spots on the leaves. You may also find fine webs.

To get rid of this weed leaf problem:

  • Separate the infested plants from the others
  • Prune the affected leaves
  • Thoroughly spray organic pesticides
  • Increase humidity for all the herbs since the mites survive in hot and dry environments
  • Ladybugs help get rid of them and prevent future infestations

cannabis leaf problems


Aphids are very tiny, destructive pests that also live under the leaves. They may be green, pale, or brown. They suck water and nutrients from leaves, causing marijuana leaf symptoms like:

  • Yellow discoloration
  • Drying up leaves that end up withering

As they suck, aphids leave behind a sticky substance called honeydew, attracting other pests and insects. They also spread plant diseases.

Get rid of them by pruning, introducing ladybugs, and using pesticides.

Powdery mildew

Powdery mildew is quite the stealthy cannabis leaf problem. It’s a quick-spreading fungus that’s encouraged by poor air circulation and high humidity.

You can easily identify powdery mildew since it appears as powdery or flour-like patches on the surface of leaves. It prohibits photosynthesis, so they may start to turn yellow.

To stop and prevent this marijuana leaf issue:

  • Spray your leaves with organic mildew treatments
  • Reduce and maintain humidity at 40–60%
  • Leave enough space between the plants to limit congestion
  • Ensure proper air circulation to prevent the mildew in the air from settling

Heat stress

We get pretty uncomfortable when the temperature is too high, and so does marijuana. Above 85 °F (29.44 °C), the tips and edges of leaves curl inwards, dry up and become crispy/burnt.

To save your plant from this cannabis leaf problem, you can choose to:

  • Increase the distance between the herbs and lights
  • Change your lights to the appropriate low heat grow lights
  • Introduce fans and ensure proper ventilation
  • Use an air conditioner to have better control of the temperature

For outdoor herbs, increase their shade, relocate them indoors if they’re portable, or water them when the temperature is lowest.

Bud rot

Bud rot is the final marijuana leaf issue we’ll be exploring. Similar to powdery mildew, this fungus thrives in high humidity and poor ventilation. 

It starts from the stem, turning leaves brown and dry, while gray blueish mold grows on the rotting buds.

To combat bud rot:

  • Immediately cut out the infected buds
  • Reduce humidity to the optimal range
  • Ensure your grow room is spacious with proper air circulation

Free ticket to healthy cannabis

There you have it, folks—a guide to living free of cannabis leaf problems. Remember to stay vigilant and spot a symptom or two when they appear.

We offer a variety of cannabis nutrients that cater to the different growth stages and protect and boost your weed’s growth. Feel free to contact us if the need arises.