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What Causes Cannabis Leaves to Get Dry or Crispy?


There are many reasons that the leaves of your marijuana plant can get dry or crispy. Sometimes crispy leaves can be normal, but most of the time, this means that something is wrong with your cannabis plant.

If you're seeing symptoms spreading through your marijuana plant, you need to react quickly! For example, these crispy, dry leaves with yellowing, curling and spots are caused by a mixture of heat and light stress. Simply moving the grow light further away would have helped keep the dry leaves from spreading! Don't wait!

Example of dry, crispy leaves with lots of brown spots and yellowing - caused by too much light and heat! 

 

8 Most Common Reasons for Dry, Crispy Marijuana Leaves

Check out our diagnose your sick marijuana plant page if you still don't see your symptoms here, but without further ado...

1.) Old, Light-Starved Leaves Are Dry or Crispy - May be Normal

Usually, the bottom-most leaves start to get a little crispy or yellow as they start getting old. If your dryness problem is just affecting the oldest leaves that don't get much light anymore, you likely don't need to worry.

After your plant has grown a few sets of leaves, it's very normal for the first few sets of leaves to turn yellow and die, especially if they're not getting light anymore.

This fast, healthy young vegetative cannabis plant is growing over an inch a day
 

2.) Leaves Closest to Light - Light Burn 

If the leaves affected are the ones which are closest to your lights, it's possible that the crispiness is a result of 'light burn' or 'heat burn'. You can tell if this is the cause because the only cannabis leaves affected are the ones closest to the lights or source of heat.

Light Burn (can happen even if the temperature is cool because the light is too close)

Example of cannabis symptoms caused by light burn. Yellowing top leaves under the grow lights, and the leaf margins often stay great. With light burn, leaves may turn red instead of yellow.

Cannabis suffering from light stress

This cannabis seedling is being burned by too-close LED grow lights
 

3.) Leaves Near Hot Lights - Heat Stress

Even if the grow light is a good distance away from your cannabis plants, they can still get stressed out by heat. Cannabis plants generally prefer temperatures under 85°F / 30°C, though some strains are more sensitive to heat (shorter, bushier strains are often more sensitive to heat than the longer, lankier strains). Most plants are fine with a few hot days, but if it's hot every day for weeks, your plants can really start to suffer. Most marijuana plants can handle a small heat spell, but they don't want to live in a desert! Get Learn 5 secrets to controlling heat in the grow room!

Heat Stress

A little heat will cause some problems like leaf tacoing and discoloration, like you can see with this heat-stressed marijuana seedling

Heat Stress on a thirsty outdoor cannabis plant

This plant is getting spots and other discoloration of the leaves because it's in too-hot conditions.

A hot day causes these leaves to shrivel up overnight
 

4.) Leaf Edges - Likely Nutrient Burn

If the dryness affecting leaves that are new growth, it's possible that you are you are giving your cannabis too many nutrients and it's showing the first signs of nutrient burn. Usually, the first signs of cannabis nutrient burn are yellow or brown tips on leave. 

Brown burnt tips on leaves - The first signs of nutrient burn on a marijuana seedling
 

5.) New Growth - Possibly a PH or Nutrient Problem

The last reason your cannabis may get crispy or dry leaves is due to some sort of nutrient deficiency.

Nutrient Deficiencies (These Were Caused by Incorrect pH)

The leaf edges and tips turn bright yellow during a cannabis copper deficiency

This pot plant is showing the signs of a sulphur deficiency (odd yellowing of leaves starting from the center)This marijuana plant appears to have a potassium deficiency (odd yellowing of leaves starting from the edges) which can look like nutrient burn but is actually caused by incorrect pH

A young cannabis plant with the yellow leaves of a potassium deficiency

The best way to prevent nutrient deficiencies is to make sure you're giving your plants the right type of nutrients and pHing the water to the proper level depending on your growing medium. But that doesn't mean more is better. It's important not to overload your plants with too high levels of nutrients.

Too Much Nitrogen (Nitrogen Toxicity) causes dark green leaves that often feel dry and crispy

A Nitrogen toxicity can also cause certain leaves to turn yellow, but other than that it looks nothing like a cannabis nitrogen deficiency

Magnesium Deficiency

This marijuana leaf is showing signs of a magnesium deficiency (yellow stripes in between the veins)

Iron Deficiency

Example of a cannabis plant that has yellow leaves as the result of an iron deficiency

How to Fix

  • First, check the pH.
  • If a Magnesium or Iron deficiency, consider getting a Cal-Mag supplement that is made for plants (you should always add Magnesium and Calcium at the same time because these two nutrients work together closely in the cannabis plant, and are important in iron uptake).
  • If grow lights are on a 24/0 schedule, change to 18/6 and move the lights up a few inches. This nighttime break and slightly lower levels of light will help an ailing plant recover more quickly. Once the plant is growing fast and healthy again, you can go back to full power.
  • If you don't know what type of nutrients to use, I recommend using the General Hydroponics Flora trio for hydro or coco, and Fox Farms Soil Nutrient Trio for your soil grow. 
  • Learn everything you need to know about cannabis nutrients!

Fox Farm Soil Trio is great for soil grows

Get the Fox Farms trio nutrient for growing cannabis in soil - lots of great stuff for your roots, get it on Amazon!

General Hydroponics Flora trio is great for coco coir or hydroponic grows!

Get the General Hydroponics Flora Trio on Amazon.com
 

6.) Root Problems, Root Rot or Bad Watering Practices 

Chronic overwatering can sometimes cause unusual deficiencies even if the pH is spot on, like this plant grown in muddy soil. The biggest sign that these symptoms are caused by overwatering and not pH (or something else) is that the plant is always droopy. 

This apparent cannabis potassium deficiency looks like a pH problem, but it's actually been caused by overwatering

Another example of a deficiency that's actually caused by overwatering (notice how this seedling is also droopy)

Another example of a deficiency caused by overwatering

Root Rot

Example of a sick cannabis leaf caused by root rot

The burnt discolored leaves of a cannabis plant with root rot

 

7.) Bugs or Mold

If your plant gets bugs, it can cause lots of symptoms including dry, crispy leaves!

Dry, crispy, yellow leaves caused by a fungus gnat infestation

Cannabis leaves damaged by fungus gnats

Bud Rot

One of the first signs of bud rot is often yellow leaves where the mold is taking hold

Broad Mites

Example of leaf damage from broad mites or russet mites
 

8.) Other Possible Causes

If you accidentally spill full-strength nutrient filled water on some of your leaves and don't wipe it off, it's possible that they will get burned from this as well, either from the nutrients or the lights being magnified by the water.

Another thing to think about is, "Did anything different happen right before I started seeing problems?" Was there a hot day, a new supplement, or some other change? Sometimes this might give you a hint to the cause!

Did Anything Different or Unusual Happen Recently?

If you've gone through this tutorial and are still having problems, check out this page which explains the symptoms of nutrient deficiencies in marijuana!

If you have anything to add, or if you have any other questions, I'd love to hear from you regarding your experiences growing weed!

 


 

More Resources for Cannabis Plant Problems

Cannabis Problems Guide

Diagnose Your Sick Plant

Bugs & Other Cannabis Pests

How to Prevent Nutrient Deficiencies

7-Step Remedy That Fixes 99% of Grow Problems

 


 

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