Cannabis plants require a variety of nutrients to grow and produce healthy flowers. The three main nutrients that cannabis plants need are nitrogen, phosphorus, and potassium, which are commonly referred to as NPK. In addition to these primary macronutrients, cannabis plants also require secondary macronutrients and micronutrients to grow and produce high yields.
Primary Macronutrients
Nitrogen (N)
Nitrogen is an essential nutrient for cannabis plants during the vegetative stage. It is responsible for leafy growth and the development of new stems and branches. Nitrogen is a crucial component of chlorophyll, the molecule that helps plants produce energy from light. Plants that lack nitrogen will have yellowing leaves and stunted growth because they cannot produce enough chlorophyll.
There are several ways to add nitrogen to a cannabis grow. Organic fertilizers like compost, worm castings, and blood meal are good sources of nitrogen. Synthetic fertilizers like ammonium nitrate and urea are also good sources of nitrogen, but they can be harmful to the environment and difficult to use correctly.
Phosphorus (P)
Phosphorus is needed by cannabis plants during the flowering stage. It is responsible for the development of strong roots and the production of flowers. Phosphorus is a vital component of adenosine triphosphate (ATP), the molecule that helps plants store and use energy. Plants that lack phosphorus will have purplish leaves and poor flower development because they cannot produce enough ATP.
Phosphorus can be added to a cannabis grow using organic or synthetic fertilizers. Organic sources of phosphorus include bone meal, rock phosphate, and guano. Synthetic fertilizers like superphosphate and triple superphosphate are good sources of phosphorus, but they can be expensive and difficult to use correctly.
Potassium (K)
Potassium is important for overall plant health and helps with stress tolerance, disease resistance, and water uptake. Potassium is a crucial component of stomata, the microscopic pores on leaves that regulate water loss and gas exchange. Plants that lack potassium will have yellowing and curling of leaves, and poor flower development because they cannot regulate water loss and gas exchange effectively.
Potassium can be added to a cannabis grow using organic or synthetic fertilizers. Organic sources of potassium include wood ash, kelp meal, and granite dust. Synthetic fertilizers like potassium sulfate and potassium chloride are good sources of potassium, but they can be harmful to the environment and difficult to use correctly.
Secondary Macronutrients
Calcium (Ca)
Calcium is important for cell wall development and root growth. Calcium helps to build strong cell walls and improve the overall structure of the plant. Plants that lack calcium will have stunted growth and poor root development because they cannot build strong cell walls.
Calcium can be added to a cannabis grow using organic or synthetic fertilizers. Organic sources of calcium include bone meal, eggshells, and dolomite lime. Synthetic fertilizers like calcium nitrate and calcium chloride are good sources of calcium, but they can be expensive and difficult to use correctly.
Magnesium (Mg)
Magnesium is needed for chlorophyll production and photosynthesis. Magnesium is a crucial component of the chlorophyll molecule and helps plants produce energy from light. Plants that lack magnesium will have yellowing leaves and poor growth because they cannot produce enough chlorophyll.
Magnesium can be added to a cannabis grow using organic or synthetic fertilizers. Organic sources of magnesium include Epsom salt, dolomite lime, and compost. Synthetic fertilizers like magnesium sulfate and magnesium oxide are good sources of magnesium, but they can be expensive and difficult to use correctly.
Sulfur (S)
Sulfur is important for amino acid production and protein synthesis. Sulfur helps plants produce amino acids, which are the building blocks of proteins. Plants that lack sulfur will have yellowing leaves and poor growth because they cannot produce enough amino acids.
Sulfur can be added to a cannabis grow using organic or synthetic fertilizers. Organic sources of sulfur include gypsum, compost, and manure. Synthetic fertilizers like ammonium sulfate and potassium sulfate are good sources of sulfur, but they can be harmful to the environment and difficult to use correctly.
Micronutrients
Micronutrients are needed in small quantities but are still important for plant growth and development. There are many micronutrients that cannabis plants need, including iron, zinc, manganese, copper, boron, and molybdenum.
Iron (Fe)
Iron (Fe) is important for chlorophyll production and helps plants produce energy from light. Plants that lack iron will have yellowing leaves and poor growth because they cannot produce enough chlorophyll. Iron can be added to a cannabis grow using organic or synthetic fertilizers. Organic sources of iron include blood meal, kelp meal, and fish emulsion. Synthetic fertilizers like iron sulfate and iron chelate are good sources of iron, but they can be expensive and difficult to use correctly.
Zinc (Zn)
Zinc (Zn) is important for enzyme production and helps plants use nutrients effectively. Plants that lack zinc will have stunted growth and poor nutrient uptake because they cannot produce enough enzymes. Zinc can be added to a cannabis grow using organic or synthetic fertilizers. Organic sources of zinc include compost, manure, and rock dust. Synthetic fertilizers like zinc sulfate and zinc chelate are good sources of zinc, but they can be expensive and difficult to use correctly.
Manganese (Mn)
Manganese (Mn) is important for photosynthesis and helps plants produce energy from light. Plants that lack manganese will have yellowing leaves and poor growth because they cannot produce enough energy. Manganese can be added to a cannabis grow using organic or synthetic fertilizers. Organic sources of manganese include compost, manure, and rock dust. Synthetic fertilizers like manganese sulfate and manganese chelate are good sources of manganese, but they can be expensive and difficult to use correctly.
Copper (Cu)
Copper (Cu) is important for enzyme production and helps plants use nutrients effectively. Plants that lack copper will have stunted growth and poor nutrient uptake because they cannot produce enough enzymes. Copper can be added to a cannabis grow using organic or synthetic fertilizers. Organic sources of copper include compost, manure, and rock dust. Synthetic fertilizers like copper sulfate and copper chelate are good sources of copper, but they can be expensive and difficult to use correctly.
Boron (B)
Boron (B) is important for cell wall development and helps plants use calcium effectively. Plants that lack boron will have stunted growth and poor root development because they cannot build strong cell walls. Boron can be added to a cannabis grow using organic or synthetic fertilizers. Organic sources of boron include compost, manure, and seaweed. Synthetic fertilizers like borax and boric acid are good sources of boron, but they can be harmful to the environment and difficult to use correctly.
Molybdenum (Mo)
Molybdenum (Mo) is important for nitrogen fixation and helps plants use nitrogen effectively. Plants that lack molybdenum will have stunted growth and poor nitrogen uptake because they cannot fix nitrogen effectively. Molybdenum can be added to a cannabis grow using organic or synthetic fertilizers. Organic sources of molybdenum include compost, manure, and rock dust. Synthetic fertilizers like sodium molybdate and ammonium molybdate are good sources of molybdenum, but they can be expensive and difficult to use correctly.
Stages of Nutrients
Vegetative
Your cannabis plants will require nutrients during the vegetative stage to support healthy growth. Nitrogen is especially important during this stage, as it is needed for leaf development and stem growth. You can use a high-nitrogen fertilizer or organic amendments, such as blood meal or fish emulsion, to provide your plants with the nutrients they need.