Leaf Health & Deficiencies
Leaf Burn
Leaf burn is damage to a cannabis plant’s leaves that causes the tips or edges to turn brown, yellow, or crispy. It usually occurs when the plant receives too many nutrients, too much heat, or excessive light.
What Leaf Burn Is and What Causes It
Leaf burn is a physiological condition in cannabis plants where leaf tissue becomes damaged due to environmental or chemical stress. It is most commonly associated with excess nutrient salts, high temperatures, or overly intense light exposure, all of which can overwhelm the plant’s ability to regulate water and nutrient movement within its tissues.
How Excess Nutrients Cause Leaf Burn
In cannabis cultivation, nutrient burn is the most frequent form of leaf burn. This occurs when fertilizer concentrations are too high, causing excess salts to accumulate in the growing medium or root zone. These salts draw water out of plant cells through osmotic pressure, dehydrating leaf tissue and resulting in burnt-looking tips or margins. Symptoms typically begin at the leaf tips and progress inward if the issue is not corrected.
Heat and Light Stress as Causes of Leaf Damage
Heat and light stress can also cause leaf burn. High temperatures increase transpiration and water demand, while intense light can overload the photosynthetic system. When these stresses exceed the plant’s tolerance, leaf tissue dries out or becomes damaged, especially on upper leaves closest to the light source. In severe cases, affected areas may appear bleached, brittle, or necrotic.
Root and Nutrient Imbalances That Contribute to Leaf Burn
Leaf burn may also occur as a secondary effect of nutrient imbalance or poor root function. Damaged or oxygen-deprived roots can impair water uptake, making leaves more vulnerable to environmental stress. While leaf burn itself is not a disease, it is a clear warning sign that growing conditions are out of balance.
How Leaf Burn Affects Growth and Recovery
If left unaddressed, leaf burn can reduce photosynthesis, slow growth, and limit overall plant productivity. However, when the underlying cause is identified early and corrected, new growth typically returns to a healthy appearance, even though damaged leaf tissue does not recover.
Related terms:
Nutrient Burn, Fertilizer, Electrical Conductivity (EC), Salt Buildup, Heat Stress, Light Stress, Root Zone, Transpiration.
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