What's Wrong With My Plant? - How to Diagnose Nutrient Deficiencies in Cannabis
Updated: May 23
If you've ever grown cannabis, you know just how easily nutrient deficiencies can occur. Fortunately, most cases of nutrient deficiencies and toxicities have simple solutions.
In this article, we're going to discuss
Leaf anatomy
Symptoms of essential nutrient deficiencies & toxicities
The importance of pH to nutrient availability
Treatment options for correcting nutrient imbalances
Table of Contents
The Plant Nutrient Deficiency Chart
Diagnosing a Nutrient Deficiency
Understanding Nutrients
Nutrients are vital for plant growth and diagnosing nutrient can be difficult if you don't understand how nutrients interact with each other.
Before we learn how to diagnose nutrient deficiencies in cannabis plants, we'll need to learn a bit about how nutrients work on a cellular level.
Leaf Anatomy
Before we go any further, lets define a few terms:
Macronutrients
Macronutrients are elements that plants need in large quantities. These nutrients have a direct effect on critical plant functions, like amino acid (protein) formation, photosynthesis, and cellular respiration.
Nitrogen, phosphorus, potassium, calcium, magnesium, and sulphur all fall into this category.
Micronutrients
Micronutrients play an indirect role in plant biology and must be present for certain chemical reactions to take place; such as protein synthesis and regulating osmotic pressure.
Micronutrient deficiencies often occur simultaneously.
Iron, boron, manganese, copper, molybdenum, chlorine, zinc, cobalt, vanadium, silicon, and sodium are all micronutrients.
Mobile vs. Immobile
In addition to being micro or macro, nutrients can also be categorized as Mobile or Immobile.
Mobility affects where nutrient deficiencies first appear so by understanding which nutrients fall into which categories, we are able to diagnose nutrient issues more accurately.
The NPK Ratio
The NPK ratio is prominently featured on the front of most nutrient products and soils. The NPK ratio represents the percentage (by volume) of Nitrogen, Phosphorus, and Potassium that the product contains.
Why is pH Important?
The plant's ability to absorb nutrients is heavily dependant on the pH of the soil in which the plant resides. Macronutrients tend to be more available at higher pH levels whereas micronutrients tend to be more available at lower pH levels.