Phosphorus (P) is one of three essential macronutrients for cannabis, along with nitrogen (N) and potassium (K). Phosphorus is required for all known life forms and is particularly important for many critical plant functions such as :

  • Early root development
  • Essential for plant metabolism
  • Nutrient uptake
  • Stem strength
  • Disease resistance
  • Frost resistance
  • Flower formation
  • Increasing yield
  • Improving bud quality

Phosphorus is essential for all aspects of cannabis growth and development. A lack of phosphorus will lead to unhealthy plants. Most commercial cannabis nutrients contain adequate amounts of phosphorus, although deficiencies may occur due to poor soil quality, pH issues or other environmental factors.

Most cannabis plants will not require additional nutrients in the early stages until about the third week as there should be adequate amounts of phosphorus in the soil. During the vegetative stage, from about the fourth week on, plants require nutrients rich in N-P-K, with about 200 ppm of N, 120 ppm of P, and 200-250 ppm of K. Additional nutrients are required during the pre-flowering stage with about 200-250 ppm of N-P-K. When the vegetative stage ends and the flowering stage begins, cannabis plants require increased levels of phosphorus and potassium with very little nitrogen.