Lesson 06: Cannabis Nutrient Requirements and Deficiencies

Every single plant on the planet, like all other living things, need food for their growth and development. Without the right nutrients at the right times Good Medicine would not be possible. Cannabis nutrients can be broken down into available elements through time, soil availability, biological, and chemical reactions. Cannabis requires 16 essential elements derived from nutrients to grow from seedling, vegetative plant, and flowering plant. Carbon, hydrogen, and oxygen are derived from the air in the atmosphere, soil or growing media provided for the cultivation system, and balanced water. The other crucial 13 essential elements are nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, zinc, manganese, copper, boron, molybdenum, and chlorine. [1]

These nutrients are supplied from a unique combination soil mineral, soil organic matter, sugars, biological activity or by organic or inorganic fertilizers depending on the system, certifications, and preferred method of cultivation. For you to have healthy grows and optimal yields, nutrients, light, heat, and water must be adequately supplied throughout the duration of the grow. Cultural practices and control of diseases and insects also play important roles in crop production besides just nutrient sources and availability.

Nutrient requirements for each plant are determined by a myriad of different factors starting with the genetics of the plant, the species of the plant, the environment it is being grown in, when it was started (season, indoors, etc.), and the experience of the system that it is placed in. In this lesson we are going to cover the macro and micronutrients required to cultivate the Good Grow.

As you begin to understand the elements required for a successful system you will need to know their ability to move throughout the plant from the soil horizon. You will need to know the plants mobility. No, the plant isn’t going to move and grab these nutrients and nor will these nutrients grow legs to feed your plant, but the pH of your water and the plants natural respiratory actions will move some of the nutrients throughout the plants tissue from the soil and nutrients you place into it.

Nutrient Mobility

When the grower has an understanding what element has mobility in the plant the grower will be able to identify deficiencies, optimize grow cycles, and be able to tangibly quantify nutrient amounts per crop turn more effectively.

Mobile

The elements that can be moved through the plants tissue with growth are mobile nutrients. These are nutrients that can be moved throughout the plants from older growth to new growth. For these elements you will be able to determine the deficiency by observing it older plant growth first.

Elements Mobility in Plant Nutrient Deficiency Location
Nitrogen (N) Mobile Old Leaves
Phosphorous (P) Mobile Old Leaves
Potassium (K) Mobile Old Leaves
Magnesium (Mg) Mobile Old Leaves


Immobile

When elements cannot be moved from old growth to new growth it is an immobile nutrient. These mineral nutrients are usually an indication of depletions in the plant tissue and soil horizon and will show in the new growth because of the depletion.

Elements Mobility in Plant Nutrient Deficiency Location
Calcium (Ca) Immobile New Leaves
Sulfur (S) Immobile New Leaves
Iron (Fe) Immobile New Leaves
Manganese (Mn) Immobile New Leaves
Boron (B) Immobile New Leaves
Molybdenum (Mo) Immobile New Leaves
Zinc (Zn) Immobile New Leaves


Nitrogen

The first letter on all nutrient and fertilizer bags, nitrogen. Nitrogen has the elemental symbol: N; is available to cannabis as nitrate ((NO3 –, and ammonium (NH4+) ions. Nitrogen is rightfully mentioned first because it is a critical element for optimal crop production, determines the success of the season, and has a significant impact on economic return for cultivators. Nitrogen is a mobile macronutrient that plays a significant role in photosynthesis and changes forms in the soil horizon. It exists in as much as four different forms depending on the chemical and biological influences.

The organic nitrogen for plants is made available by the biological cycle of microorganisms in the soil changing atmospheric nitrogen (dinitrogen N2) into nitrates by way of bacteria, algae, and other natural means to ammonium then to nitrate (NO3) in the soil. Nitrate is the most used form of nitrogen and is crucial for healthy growth and development throughout each stage of the photoperiod. It can be lost through over watering and through nutrient lockout through poor pH management. The ammonium form of nitrogen is directly utilized for protein creation in plants and not as easily lost in the soil horizon. If you do not find the optimal range for your plant during the growth cycle you will cause deficiencies or excesses that will damage your final yield, come harvest.

 

Nitrogen Deficiencies

A deficiency in this nutrient will be observed in the oldest leaves on the plant due the nutrient's mobility. It will result in the yellowing of older fan leaves, leaves dropping off of the plant, and the eventual yellowing and discoloration of the entirety of the plant. This will significantly reduce the yields of the plant and will result in a total crop failure.


Common Observations of Nitrogen Deficiencies

• Yellowing Leaves
• Wilting Leaves
Prevention of Nitrogen Deficiencies
• Keep pH in soil within an optimal range (5.8-6.5) to prevent nutrient lockout
• Utilize the correct Peace Pipe Potting mix for a nutrient dense soil media. Vegetative Outdoor for the vegetative plant.
• Utilize Comanche Compost to ensure nutrient dense mediums in your grow
• Add mycorrhizae to boost the number of nitrogen-fixing bacteria (they convert unavailable nitrogen and ammonium to more available forms of nitrate), to boost nitrogen levels.


Phosphorus
The second letter of the most recognized acronym of agriculture's NPK, is P. Phosphorus has an elemental symbol P; available to plants as orthophosphate ions (HPO4 2 –, H2 PO4 –). Phosphorus is required for the energy storage and transfer of ADP and ATP inside the plant’s energy cycling. Phosphorus replenishes itself in a biogeochemical cycle in the ecosystem known as the phosphorus cycle: Plants that have taken up phosphorus from the ground are eaten by animals. If you look at the Phosphorus Cycle Figure you can see

[1] ch3 (hawaii.edu) Essential Nutrients for Plant Growth: Nutrient Functions and Deficiency Symptoms R. Uchida Accessed January 16, 2021