Which nutrients do cannabis plants require?


Cannabis plants need three main nutrients in order to thrive.

These are nitrogen (N), phosphorus (P), and potassium (K), and they form the cornerstone of cannabis plants’ health. As such, these three nutrients are usually boldly displayed on fertiliser products in the form of an NPK ratio. The higher the number for each value, the higher the concentration of that particular nutrient.

  • Nitrogen is mostly responsible for a cannabis plant’s growth during the vegetative stage of its life. It’s a crucial part of chlorophyll production, and without it, a plant can’t turn sunlight into energy, and subsequently won’t be able to grow. It is also crucial for the formation of amino acids which act as building blocks for proteins in the plant.

  • Phosphorus is especially important for early-stage root development, stem strength, resistance to disease, nutrient uptake, flower formation, and yield.

  • Potassium plays several key roles which control the mechanisms through which plants maintain optimal health, including the regulation of water and salt concentrations in the plant, which is achieved by controlling the opening and closing of the stomata, and is how a plant exchanges CO2, H2O, and oxygen.

However, cannabis needs more than just three nutrients to survive; it also requires secondary nutrients like calcium, magnesium, and sulfur, which play equally important roles.

  • Calcium is important for cell wall development, can help reduce soil salinity, and improves water penetration when used as a soil amendment.

  • Magnesium plays a key role in photosynthesis and carbohydrate metabolism, and also helps with the stabilisation of plant cell walls.

  • Sulfur is necessary for the formation of chlorophyll and the production of proteins, amino acids, enzymes and vitamins, and protects plants against disease.

Aside from the nutrients mentioned above, cannabis plants also make use of several other nutrients in small quantities (micronutrients), which are also very necessary for them to thrive. These include boron, chlorine, copper, iron, manganese, molybdenum, and zinc.


Info on nutrient schedules based on life cycle stage to follow later on this week, along with organic vs synthetic nutrient comparisons.


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