[Sticky] Macro and Micro Nutrients in a Cannabis Plant
Macro and Micro Nutrients in a cannabis plant are the elements that are important to plant growth. The three major macronutrients are:
All cannabis growing nutrients will have these three elements in them. The N-P-K ratios will of your nutrients will be displayed as three numbers such as; 1-2-3. 1, being Nitrogen, 2 being Phosphorus, and 3, being Potassium.
During their vegetative stage, cannabis plants need more “N” and “P”, for energy and growth of leaves and stems. In their flowering-stage, more “P” and “K” will be needed, to build bigger flowers and provide the plants with lots of energy.
If you have any questions about how a cannabis plant uses its nutrients, then feel free to ask for help in our cannabis growers forum
Along macronutrients, plants also require micronutrients. They will be used in smaller doses than NPK, but they are still just as important to healthy plant growth.
Some of these micronutrients are Calcium (Ca), Magnesium (Mg), Sulfur (S), Manganese (Mn), Boron (B), Zinc (Zn), and Copper (Cu).
List of Macro and Micro Nutrients in a Cannabis Plant
Below is a list of macronutrients and micronutrients. along with information on how it is used by a cannabis plant. There will also be descriptions of deficiencies and excess for each nutrient.
Uses in Cannabis Growing: Nitrogen promotes photosynthesis, and is directly responsible for the production of chlorophyll. It stimulates leaf and stem growth, and aids the overall size and vigor of the plants.
Nitrogen Deficiency: A nitrogen-deficiency can be recognized by reduced growth-rates and yellowing of the leaves. This will start with the older/lower leaves).
Nitrogen Excess: Leaves will be dark green, and suffer from "The Claw". The leaf tips will curl under. Most importantly, if the plant is in flower, the buds will have low density and be "Airy".
Macronutrient : Phosphorus
Uses in Cannabis plants: Phosphorus aids in the germination of seeds, and the growth of seedlings and roots. It is also vital the production of terpenes, resins, flowers, and starches. Phosphorus also influences overall plant vitality.
Phosphorus Deficiency: A phosphorus-deficiency will cause a cannabis plants growth-rates to slow down. Also smaller leaves which wilt. The leaves will be a dull, bluish-green, which will turn purplish or bronzy, and will have seared edges.
Phosphorus Excess: The top leaves of the cannabis plant will develop yellow veins, and the tips will show signs of nutrient burn. Lower leaves will develop spots.
Uses in cannabis plants: Potassium is important to your cannabis plants for metabolic changes during flowering, and the production of flowers. It also promotes general plant-vigor, disease-resistance, and strong growth.
Potassium Deficiency: A potassium-deficiency will slow down growth-rates. It will also cause leaf-tips and edges to become a scorched-brown colour, with curled margins.
Potassium Excess: The root zone of a cannabis plant will become acidic if it has too much potassium. As a result, roots can be damaged. This will affect the overall intake of nutrients. Because of this, potassium excess will display symptoms of many other Macro and Micronutrient deficiencies.
Micro Nutrients in a Cannabis Plant
Element Name: Calcium
Uses in Cannabis Plants: Calcium is a key ingredient in cell-walls. It strengthens stems, stalks and branches. It also contributes to root-development/growth, mostly that of the root-tips.
Calcium Deficiency: Calcium-deficiency can be recognized by distorted leaves, with hooked tips and curled margins. A deficiency would also result in under-developed roots, with weak root-tips.
Calcium Excess: Red and orange spots will develop on leaves. Your plants will also suffer from nutrient lock out and show signs of many deficiencies.
Element Name: Magnesium
Uses in Cannabis Plants: Magnesium is significant for chlorophyll-production and most enzyme reactions. It is responsible for healthy leaf-structure and production, as well as sustaining healthy vein-structure in the leaves.
Magnesium Deficiency: A magnesium deficiency will affect various plant species differently. The most common symptoms in cannabis plant are a vivid yellowing of the leaves, followed by leaves falling without withering, starting with the older/lower leaves.
Magnesium Excess: Excessive “Mg” levels may initiate a calcium-deficiency. Leaves will be dark, and show signs of salt build up, with leaf tip burns.
Element Name: Sulfur
Uses in Plants: Sulfur, being an ingredient in plant-proteins, is vital for protein-production, chlorophyll-production and vegetative growth.
Sulphur Deficiency: A sulfur deficiency can be identified by slowed down growth-rates. This will also be accompanied by small, mutated leaves which are round in shape and roll upwards. Also, leaves will become stiff and brittle, and will fall off. A “S” deficiency will also cause flowers on the top of colas to die.
Sulphur Excess: General nutrient burn, with dark green leaves. A plant with sulphur excess will grow shorter with uneven growth.
Element Name: Manganese
Uses in a Cannabis Plant: Manganese is a catalyst for many enzymes, and also aids photosynthesis/ chlorophyll-production.
Manganese Deficiency: Firstly, you must consider a manganese-deficiency will have varying symptoms, depending on plant-species. The most common symptoms in cannabis plants are a yellowing of chloroplasts while stems remain relatively green. White or grey specks/spots may develop on the surfaces of leaves. As is usually the case, older/lower leaves will be affected first.
Manganese Excess: Excessive “Mn” levels may cause an “Fe”(iron) deficiency, which will exhibit symptoms similar to a “Mn” deficiency. New leaves will develop orange , to brown, coloured patches.
Element Name: Boron
Uses in Cannabis Growing: Boron aids the movement of necessary sugars, as well as reproduction, and water intake by cells. It also assists in the production of stems, stalks and branches, and keeps calcium in a soluble form. Furthermore, “B” contributes to leaf-production:-colouring and structure.
Boron Deficiency: A boron deficiency can be recognized by symptoms such as; distorted and dead growing tips, hollow stems, and malformed flowers. Plants suffering from a “B” deficiency frequently exhibit scorched, curled leaves, which are often spotted and discolored; young/vegetative leaves are affected first.
Boron Excess: Excessive “B” levels may cause plants to exhibit symptoms similar to those of “Mg”/”K” deficiencies. Leaves will droop, and begin to turn yellow.
Element Name: Zinc
Uses in Cannabis Plants: Zinc levels directly affect plant size and maturation, as it is necessary for the production of plant proteins. Consequently, “Zn” is vital to the production of leaves and stalks/stems/branches.
Zinc Deficiency: A deficiency of zinc will result in the yellowing of chloroplasts between leaf veins, usually with purplish spots of dead cells on leaf surfaces. You will find older/lower leaves are the first to show symptoms. Vegetative growth is deformed, and floral growth is reduced.
Zinc Excess: Excessive “Zn” levels can initiate an “Fe”(iron) deficiency. But this is very rare as it is only found in small amounts in cannabis growing nutrients.
Element Name: Copper
Cannabis Plant Uses: Copper is responsible for healthy, vigorous growth, and strengthens stalks/stem/branches. It is also necessary for the production of plant proteins, and is crucial for reproduction.
Copper Deficiency: A copper deficiency can cause otherwise green leaves to adopt a bluish hue. As a result of copper deficiency, vegetative growth may fail to unfold, and may be yellow at the tips and edges.
Copper Excess: Roots will become thick, slow down in growth, and in worse cases, will root and die. The plant will be less bushy, because it will grow less stems.
Final notes on Macro and Micro Nutrients
If your plants are suffering with micronutrient deficiency, adjusting your PH can probably fix it. This will bring the PH of the medium back into the correct range, and will result in the Macro and Micro Nutrients available again.
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Is this normal looking? The leaf curl happening at the flowers?
Hmm, judging by those fresh pistils, I'd guess you've just started your flowering. Right when flowering begins, the new growth starts to change, and the leaves start to become super thin and kinda weird looking - much like what you have there. The curling and contorting is a bit odd but, it seems okay to me.. at least from this angle, lol. The plant in my display pic is similar to yours I think.
I will say they do look a hungry for some Magnesium though, by the looks of that slight yellowing in the leaves.. maybe that has something to do with the curls..?
Welcome to Percys by the way. ?
Great! Thank you so much ?
Yes, flowering began very recently. This is a Northern Lights Auto from Seedsman grown in Fox Farms Ocean Forest organic soil, perlite and worm castings. I have watered with tap water, citric acid to PH down to 6.5 and cal mag. I’ve just been topping the pot with the fox farms & perlite mix and using Great White Mycorrhizae instead of adding nutrients to the water.
I will Up the Calmag & hopefully that will fix the curling.
This is my first grow inside. I like the way is smells up the area ?
Welcome to Percys Tess, the plants look great! A little yellowing in the veins, but I think TG is right that it might be magnesium, which is common at this stage of growth.
Flowers are still small, I would consider spraying them with some epsom salts, just a fine mist will be fine not too uch. But this will deliver the MAG directly to the plants where they need it.
Go for half a tea spoon per litre, not a full one in this case. This should get yer to green up a bit more 🙂
Great advice! Thank you so much! I am going to do this when the lights go off in the morning ?
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