Select Page

Medical Marijuana Essential Nutrients

When growing medical marijuana, plant nutrition is essential to know for overall plant health and growth. Nutrition is defined as the process of producing food. Minerals are required by plants for various synthetic activities and production of energy, which are called nutrients. Medical marijuana plants require different elements for their growth and development these are called mineral nutrients. Soil or the grow medium is the source of the mineral nutrients and plants absorb these by their roots.


There are sixteen elements that are essential for normal healthy growth of medical marijuana. It was found that plants contain 60 elements but only 16 were observed to be essential for the growth of a plant.

These 16 elements can be categorized as macro and micronutrients. There are 9 macronutrients, which are required in large quantities. Carbon, hydrogen, oxygen, nitrogen, sulfur, phosphorus, calcium, potassium, and magnesium are all macronutrients. N-P-K is present in macronutrients. There are 7 micronutrients, which are required in small quantities or trace amounts. Iron, manganese, boron, copper, zinc, molybdenum, and chlorine are all micronutrients. A complete diet for your medical marijuana includes all 9 macronutrients and all 7 micronutrients. To figure out how much fertilizer to give your medical marijuana you need to know how much is already present in the water and grow medium. The nutrients in the grow medium or reservoir changes as the plant absorbs nutrients. It is a good idea not only to measure nutrients carefully but measure ppm and PH with testing devices. It is always best to check the labels of fertilizers to see exactly what nutrients are in the fertilizer.

The following nutrients, nitrogen, phosphorus, and potassium play a crucial role in the development of your medical marijuana. They play an important role in root growth, flowering, bud development, and in yield. The need for critical nutrients such as nitrogen, phosphorus, and potassium varies with the growing conditions and changes during the plant’s life cycle. Medical marijuana uses more nitrogen during the vegetative cycle than in flower stages. The plant’s use of phosphorus increases when the plant begins to flower, while the need for potassium increases after fertilization to aid in flower formation and seed production. A plant’s nitrogen requirements vary with light intensity and temperature. It is suggested for plants under hot conditions to be given 10-20 percent less nitrogen. It is recommended for plants growing under cooler conditions to have 10-20 percent more nitrogen because they will not be absorbing as much water. It is also suggested to use more nitrogen under intense light conditions and use less nitrogen in low-light conditions.

Nitrogen-Phosphorus Potassium

Macro-nutrients are nitrogen (N), phosphorus (P) and potassium (K).

Medical Marijuana Fertilizers

When feeding your medical marijuana there are numerous choices of fertilizers to choice from. The three easiest ways to meet the plant’s needs are to use liquid organic fertilizer, compost tea, or hydroponic fertilizers.

Hydroponic fertilizers are balanced and complete nutrient formulas. Non-hydroponic fertilizers often contain only macronutrients including nitrogen, phosphorus, and potassium. Organic fertilizers such as manures, guanos, and fish emulsion contain additional trace elements. Fertilizers may contain an incomplete selection of nutrients.

Nutrient solubility for growing medical marijuana

Medical marijuana plants grown in high quality soil mixes can usually get by using basic fertilizers. Medical marijuana plants grown in soilless mixes require macro and micronutrients. To ensure a well-balanced diet of nutrients some growers mix several products into a solution and switch fertilizer formulas between feedings. It is best to choose proven products from reliable and established companies and follow their recommendations. Plants grown in nutrient-rich mediums with manure, compost or time-release fertilizers may not need additional fertilizing. Additional nutrients can be used in supplemental amounts  if the plant begins to show deficiencies. Organic compost tea that is made by soaking matter or compost in water enhances the plant’s ability to absorb nutrients and fight off pests and diseases. The nutrient value of many organic compost tea varies by ingredients and is usually not well described on their labels. Organic ingredients usually contain micronutrients and macronutrients. When looking at labels make sure to look at the N-P-K ratio and see if the product contains calcium, sulfur and magnesium, which are crucial for bud formation.

Medical Marijuana Deficiencies

It is important to keep a close eye on your medical marijuana’s minor symptoms of deficiencies. If added nutrients cure deficiency, the plant usually responds within 3 to 5 days depending on what element is deficient. Many nutrient deficiencies are the result of minerals unable to be absorbed because of PH or nutrient imbalance. Rather than adding more nutrients you should first check the PH. To get nutrients to the plants parts immediately spary foliage with nutrients. Do not foliar feed during the flowering stages because this can result in mold and mildew. Do not foliar feed during darkness or within a couple hours of the night cycle. The best time to foliar feed is in the morning.

Cannabis Plant Deficiencies
Cannabis plant deficiencies by Jorge Cervantes

Medical Marijuana Macro & Micronutrients

Nitrogen is a major component of proteins, hormones, chlorophyll, vitamins and enzymes essential for plant life. Nitrogen metabolism is a major factor in stem and leaf growth (vegetative growth)
Phosphorus is necessary for seed germination, photosynthesis, protein formation. It is essential for flower and bud formation
Potassium is necessary for formation of carbohydrates, protein synthesis and cell division in roots and other parts of the plant. Enhances flavor and color, increases the oil content of buds.
Sulfur is a structural component of amino acids, proteins, vitamins and enzymes and is essential to produce chlorophyll
Magnesium is a critical structural component of the chlorophyll molecule and is necessary for the functioning of plant enzymes to produce carbohydrates, sugars, and fats. It is used for bud formation.
Calcium activates enzymes, is a structural component of cell walls. It is necessary for cell growth and division
Iron is necessary for many enzyme functions and as a catalyst for the synthesis of chlorophyll.
Manganese is involved in enzyme activity for photosynthesis, respiration, & nitrogen metabolism
Boron is necessary for cell wall formation, membrane integrity, calcium uptake & may aid in the translocation of sugars. Affects 16 functions in plants. Th functions include flowering, pollen germination, bud formation, cell division & the movement of hormones.
Zinc is a component of enzymes including auxins which is a plant growth hormone. it is essential to carbohydrate metabolism, protein synthesis & stem growth.
Molybdenum is a structural component of the enzyme that reduces nitrates to ammonia. Essential for protein synthesis.
Chlorine is involved in osmosis, the ionic balance necessary for plants to take up mineral elements and photosynthesis,

When selecting fertilizer for your medical marijuana’s diet there are numerous options and it is best to read labels and decide which ones contain the full range of macro and micronutrients.