Nutrients needed for a Cannabis plant

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Marijuana Nutrients – Macro and Micro Nutrients thumbnail

Macro-nutrients? Micro-nutrients? What are they?

Hey there and welcome (back)!
In today’s article we’re going to cover the different nutrients necessary for the well being of Marijuana. We’ll look at macro-nutrients, micro-nutrients (aka trace elements) as well as their mobility and how the Cannabis plants uses them.

Macro and Micro Nutrients for Cannabis - Table of content

Content tip : This article goes in combination with our piece on mobile and immobile nutrients used by cannabis

Macro Nutrients for Cannabis

What are considered as Macro-Nutrients are the 3 main nutrients necessary for a healthy plant. It’s important to note that all these nutrients are mobile one’s

The 3 main nutrients are:

Nitrogen (N)

Marijuana looooves Nitrogen and requires high levels of it during the vegetative stage but much lower levels once the plant enters the flowering stage.
Nitrogen is a nutrient that easily washes away and needs to be replace regularly, especially during vegetative growth.

If there’s an excess of Nitrogen when harvesting the plant the buds won’t have as good of a taste and won’t burn well. It’s important to flush well your plants before harvest.

The Purpose of Nitrogen

Nitrogen regulates the cannabis’s ability to make proteins essential for new protoplasm in the cells.
Electrically charged nitrogen allows the plant to tie proteins, hormones, chlorophyll, vitamins and enzymes together. Nitrogen is essential for the production amino acids, enzymes, nucleic acids, chlorophyll and alkaloids.
This important nutrient is mainly responsible for leaf and stem growth as well as overall size and vigor.

Nitrogen is most active in young buds, shoots and leaves. Ammonium (NH4+) is the most readily available form of nitrogen.
If you use this, be careful not to use too much since it can easily burn the plants.

The Nitrate form of nitrogen is much slower to assimilate than ammonium, and will release much slower in the soil. Hydroponic fertilizers use this slower-acting nitrogen compound and mix it with ammonium.

Phosphorus (P)

Cannabis uses the phosphorus during all stages of it life since it has different purposes at each stage. From root development during the vegetative stage to bud growth during the flowering stage, phosphorus is one of those extremely important nutrients.
As is the case with Nitrogen, Phosphorus is a Mobile element, meaning that the plant can reallocate it where ever it’s needed.

Purpose of Phosphorus

Phosphorus is nessary for photosynthesis and provides a mechanism for the energy to transfer within the plant. It’s also one of the components of DNA, it’s also associated with overall vigor, resin and seed production.
The Highest concentrations of phosphorus are found in the root-growing tips, growing shoots and vascular tissue.

Potassium (K)

Potassium is used at all stages of growth. Soils with a high level of potassium increase a plant’s resistance to bacteria and mold.

Purpose of Potassium

Potassium helps combine sugars, starches and carbohydrates which is essential to growth by cell division. It increases the chlorophyll in the foliage and helps to regulate the stomata openings so plants make better use of the light and air.
Potassium is essential in the accumulation and translocation of carbohydrates. It’s necessary to make the proteins that augment the oil content and improve the flavor in cannabis plants.
It also encourages strong root growth and is associated with disease resistance and water intake.

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Secondary Nutrients

The secondary nutrients are also used by the plants in large amounts. Rapid-growing indoor marijuana crops are able to process more secondary nutrients than most general-purpose fertilizers are able to supply.
Many growers opt to use high quality 2 and 3-part hydroponic fertilizers to supply all the necessary secondary and trace elements, but be careful since these nutrients may be present in high levels in the ground water.

It’s important to consider these values when adding nutrient supplements. If growing in a soil or soillex mix with a pH below 7 such as Peat-Lite, incorporating one cup of fine dolomite lime per gallon into the medium will ensure adequate supplies of calcium and magnesium.

Here are the main secondary nutrients:

Magnesium (Mg)

Magnesium is a mobile nutrient used a loooot and magnesium deficiencies are common, especially in acidic soils. Adding dolomite lime to acidic potting soils before planting will stabilize the pH and add magnesium and calcium to the soil.

You can also add Epsom Salts with each watering to correct magnesium deficiencies if you didn’t add dolomite when planting.
Use Epsom Salts designed specifically for plants rather than the supermarket-type in order to ensure the quality.

Purpose of Magnesium

Magnesium is found as a central atom in every chlorophyll molecule and is essential to the absorption of light energy. It aids in the utilization of nutrients. Magnesium helps enzymes make carbohydrates and sugars that are later transformed into flowers. it also neutralizes the soil acids and toxic compounds produced by the plant.

Calcium (Ca)

Calcium is an immobile nutrient, meaning that the plant cannot reallocate it if it has a deficiency, thus the newer growth will be affected.
Cannabis requires nearly as much calcium as other macronutrients. Avert deficiencies in the soil and in most soilless mixes by adding fine dolomite lime or using soluble-hydroponic fertilizers containing adequate calcium levels.

Purposes of Calcium

Calcium is fundamental to cell manufacturing and growth since it’s necessary to preserve membrane permeability and cell integrity which ensures proper flow of nitrogen and sugars.
The famous “cell walls” that plant have and not animals is composed of calcium; take it out and you have some odd growth going on.

Calcium stimulates enzymes that help build strong cell and root walls, weed plants must have some calcium at the growing tips of each root.

Sulfur (S)

Many fertilizers contain some form of sulfur, and for this reason, sulfur deficiency rarely occurs. Growers avoid elemental (pure) sulfur in favor of sulfur compounds such as magnesium sulfate. The nutrients combined with sulfur mix better in water.

Purpose of Sulfur

Sulfure is an essential building block of manu hormones and vitamins, including vitamin B1. It’s also an indispensable element in manu pant cells and seeds. The sulfate form of sulfur buffers the water pH.
Virtually all grounds, river and lake water contain sulfate. Sulfate is involved in protein synthesis and is part of the amino acid, cystine and thiamine; Which are the building blocks of proteins. Sulfure is essential in the formation of oils and flavors as well as for respiration and synthesis as well as the break down of fatty acids.

Hydroponic fertilizers separate sulfur from calcium in an “A” and “B” container.
If combined in a concentrated form, sulfur and calcium will form crude, insoluble gypsum (calcium sulfate) and settle as residue to the bottom of the tank

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Micro Nutrients (aka Trace Elements)

Micronutrients, also called trace elements or trace nutrients, are essential to chlorophyll formation and must be present in small amounts. They function mainly as catalysts to the plants process and utilization of other elements.
For best results, and to ensure that a complete range of trace elements are available, use fertilizers designed for hydroponics. High quality hydroponic fertilizers use food-grade ingredients that are completely soluble and leave no residues. If using an inexpensive fertilizer that does not list a specific analysis for each trace element on the label it’s a good idea to add soluble trace elements in a chelated form.

Chelated micronutrients are available in powdered and liquid forms. Add and thoroughly mix micronutrients into the growing medium before planting. Chelated micronutrients are available in powdered and liquid form. Make sure to thoroughly mix the micronutrients into the growing medium before planting.

Micronutrients are often impregnated in commercial potting soils and soilless mixes. Check the ingredients on the bag to ensure that the trace elements were added to the mix.

These elements are necessary in small levels and can easily reach toxic levels so be careful and always follow the the advertised volumes.

Here are the micro-nutrients were going to cover :

Zinc (Zn)

Zinc is a mobile micro nutrients and is also the most common micronutrient found deficient in arid climates as well as in alkaline soils.

What is the purpose of Zinc

Zinc works with manganese and magnesium to promote the same enzyme functions. Zinc cooperates with other elements to help form chlorophyll as well as prevent its demise. It’s an essential catalyst for most plants enzymes and auxins; It’s also crucial for stem growth.
Zinc plays a vital part in sugar and protein production and zinc deficiencies are fairly common in soils with a pH of 7 or more.

Manganese (Mn)

Manganese is an immobile nutrient and deficiency is relatively common indoors.

What is the purpose Manganese

Manganese is engaged in the oxidation-reduction process associated with the photosynthetic electron transport. This element activates many enzymes and plays a fundamental part in the chloroplast membrane system.
Manganese assists nitrogen utilization along with iron in chlorophyll production.

Iron (Fe)

Iron is another immobile element and available in a soluble chelated form that is immediately available for absorption by the roots. Deficiency indoors is common in case of alkaline soils.

What is the purpose of Iron

Iron is fundamental to the enzymes systems and to transport electrons dring photosynthesis, respiration and chlorophyll production.
Iron allows plants to use the energy provided by sugars.

A catalyst for chlorophyll production, iron is necessary for nitrate and sulfate reduction and assimilation. Iron colors the earth from brown to red, according to its concentrations.
Pants have a difficult time absorbing iron; Acidic soils normally contain adequate amounts of iron.

Boron (B)

Boron is a immobile nutrient that usually causes no problems but boron must be available during the entire lifecycle of a plant.

What is the use of Boron

Boron is still somewhat a biochemical mystery. We know that boron helps with calcium uptake and numerous plant functions. Scientists have collected evidence to suggest boron helps with synthesis, a base for the formation of nucleic acid (RNA uracil) formation. Strong evidence also supports that boron’s role in cell division, differentiation, maturation and respiration as well as a link to pollen germination.

Chlorine-Chloride (Cl)

Chloride is found in many municipal water systems and Cannabis tolerates low levels of it. Usually you won’t find it in regular fertilizers and it is very rare to see deficiencies of it, whether indoors or outdoors.
Chloride is a Immobile nutrient.

How does Cannabis use Chloride

Chlorine, in the form of chloride, is fundamental to photosynthesis and cell division in the roots and the foliage.

It also increases osmotic pressure in the cells, which opens and closes the stomata to regulate moisture flow within the plant tissue.

Cobalt (Co)

This immobile nutrient is rarely mentioned as necessary for plant growth and most fertilize labels don’t include cobalt. Cobalt deficiency virtually never happens indoors.

How does Marijuana use Cobalt

Cobalt is necessary for countless beneficial bacteria to grow and flourish; It’s also vital for nitrogen absorption.

Scientific evidence suggests this element is linked to enzymes needed to form aromatic compounds.

Copper (Cu)

Copper is an immobile nutrient concentrated in the roots for enzymes, it’s also a good fungicide.

How does the Weed plant use Copper

Copper is a component of numerous enzymes and proteins. Necessary in small amounts, copper helps with carbohydrate metabolism, nitrogen fixation and the process of oxygen reduction.

It also helps with the production of proteins and sugars.

Molybdenum (Mb)

Molybdenum is an immobile nutrient that is very, very rarely deficient.

How does the Marijuana use Molybdenum

This trace element is a part of 2 major enzyme systems that convert nitrate to ammonium. This essential element is used by the marijuana plant in very small quantities.

It’s most active in roots and seeds.

Silicon (Si)

Silicon is readily available in most soils, water and, as far as we’ve read, does not cause cannabis any issues do to deficiency or toxicity.

How does the Marijuana use Silicon

Silicon is absorbed by the plants as silicic acid and assists in keeping iron and manganese levels consistent.
It will mainly be found in the epidermal cell walls where it collects in the form of hydrated amorphous silica, but it will also be found in other cells.

Adequate and soluble, silicon guarantees stronger cell walls that resist pest attacks and increase heat and drought tolerance.

Note: Pests and diseases have a difficult time penetrating plants that are sprayed with a silicon-based repellent/insecticide.

Nickel (Ni)

Nickel is used by Enzymes to break down and use the nitrogen; it’s also essential for iron absorption. Nickel deficiency is rare and it’s generally subtly mixed with other nutrients, most commonly nitrogen.

Sodium (Na)

This is one of the problem elements, just a little bit will go a long way! Sodium is taken up by the roots very quickly and in small amounts (50 ppm). It can block enough other nutrients causing severe deficiencies as a result.
When mixed with chlorine, it turns to table salt, which is the worst possible salt to put on the plants.

Be very careful to measure your input water and ensure that it contains less than 50ppm of sodium (the less the better)

Recommended amounts of Nutrients for Cannabis

In the chart Below you’ll find the suggested amounts of soluble-salt fertilizers for indoor growers.

Keep in mind that these amounts will vary depending on the strains and which step of the life cycle your plant is in, as well as which strain she belongs to.
All values are in parts per million (ppm)


Nitrogen (N)150-1000250
Calcium (Ca)100 – 150200
Magnesium50 – 15075
Phosphorus50 – 10080
Potassium100 – 400300
Sulfur200 – 1000400
Copper0.1 – 0.50.5
Boron0.5 – 5.01.0
Iron2.0 – 105.0
Manganese0.5 – 5.02.0
Molubdenum0.01 – 0.050.02
Zinc0.5 – 1.00.5
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Until next time,
be safe and grow easy

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