I copied this from the Grow Room Forum "How to grow mj - everything you need to know" from the Fert/Feeding section.
Medical Marijuana;614028 said:Summary of Macronutrients
Macronutrients are the elements most vital to all plant-life. There are three major and most prominent macronutrients: Nitrogen (“N”), Phosphorus (“P”), and Potassium (“K”). All fertilizers contain these three fundamental elements, but in varying amounts, depending on fertilizer type/brand. The N-P-K ratio of the fertilizer will be listed on the side of the container/box in the form of three numbers separated by hyphens (e.g. 20-20-20, etc.); choose a fertilizer that correlates with your specific needs and stage of plant-growth. TIP: In their vegetative state, cannabis plants thrive primarily on “N” and “P”; and in their flowering-stage, “P” and “K” become more essential.
Summary of Micronutrients
Along with the basic macronutrients, plants also require micronutrients (or Trace-Elements) for sustained health and vigor. Some of these trace-elements are Calcium (“Ca”), Magnesium (“Mg”), Sulfur (“S”), Manganese (“Mn”), Boron (“B”), Zinc (“Zn”), and Copper (“Cu”). They are present in most, if not all, fertilizers, but in generally lesser portions than the major macronutrients.
Below is a list of the basic macronutrients and micronutrients/trace-elements, along with the horticultural-benefits and deficiency-symptoms of each:
# Element Name: Nitrogen
# Symbol: N
# Atomic Number: 7
# Atomic Mass: 14.00674
# Horticultural-Benefit: 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.
# Deficiency-Symptoms: A nitrogen-deficiency can be recognized by reduced growth-rates and yellowing of the leaves (starting with the older/lower leaves). Colder soil-temperatures make nitrogen less-available to plants.
# Element Name: Phosphorus
# Symbol: P
# Atomic Number: 15
# Atomic Mass: 30.973762
# Horticultural-Benefit: Phosphorus aids in the germination of seeds, and the growth of seedlings and roots. It is also vital the production of terpene resins, floral clusters, and necessary sugars and starches. Phosphorus also influences overall vigor.
# Deficiency-Symptoms: A phosphorus-deficiency can be noted by reduced growth-rates and the production of smaller leaves which wilt/drop quickly. The leaves will be a dull, bluish-green, which will turn purplish or bronzy, and will have seared edges. Excessive “P”-levels can initiate a potassium-deficiency.
# Element Name: Potassium
# Symbol: K
# Atomic Number: 19
# Atomic Mass: 39.0983
# Horticultural-Benefit: Potassium is important to your plants for metabolic changes during flowering, and the production of floral clusters. It also promotes general plant-vigor, disease-resistance, and sturdy growth.
# Deficiency-Symptoms: A potassium-deficiency will retard growth-rates, and cause leaf-tips and -edges to become a scorched-brown color, with curled margins.
# Element Name: Calcium
# Symbol: Ca
# Atomic Number: 20
# Atomic Mass: 40.078
# Horticultural-Benefit: Calcium is a key ingredient in cell-walls. It strengthens stems/stalks/branches, and also contributes to root-development/growth, primarily that of the rot-tips.
# Deficiency-Symptoms: A 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.
# Element Name: Magnesium
# Symbol: Mg
# Atomic Number: 12
# Atomic Mass: 24.3050
# Horticultural-Benefit: 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.
# Deficiency-Symptoms: A magnesium-deficiency will affect various plant-species differently. The most common symptoms in cannabis plants are a vivid yellowing of the leaves, followed by leaves falling without withering, starting with the older/lower leaves. Excessive “Mg”-levels may initiate a calcium-deficiency.
# Element Name: Sulfur
# Symbol: S
# Atomic Number: 16
# Atomic Mass: 32.066
# Horticultural-Benefit: Sulfur, being an ingredient in plant-protiens, is vital for protein-production, chlorophyll-production and vegetative growth.
# Deficiency-Symptoms: A sulfur-deficiency can be identified by retarded growth-rates, accompanied by small, mutated leaves which are round in shape and roll upwards. Leaves will become stiff and brittle, and will fall off. A “S”-deficiency will also cause flowers on the top of kholas to die.
# Element Name: Manganese
# Symbol: Mn
# Atomic Number: 25
# Atomic Mass: 54.93805
# Horticultural-Benefit: Manganese is a catalyst for many enzymes, and also aids photosynthesis/ chlorophyll-production.
# Deficiency-Symptoms: 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. Excessive “Mn”-levels may cause an “Fe”(iron)-deficiency, which will exhibit symptoms similar to a “Mn”-deficiency.
# Element Name: Boron
# Symbol: B
# Atomic Number: 5
# Atomic Mass: 10.811
# Horticultural-Benefit: 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/branches, and keeps calcium in a soluble form. Furthermore, “B” contributes to leaf-production/-coloring/and -structure.
# Deficiency-Symptoms: A boron-deficiency can be recognized by distorted and/or dead growing tips, hollow stems, and malformed fruits/flowers. Plants suffering from a “B”-deficiency frequently exhibit scorched, curled leaves, which are often spotted and discolored; young/vegetative leaves are affected first. Excessive “B”-levels may cause plants to exhibit symptoms similar to those of “Mg”-/”K”-deficiencies.
# Element Name: Zinc
# Symbol: Zn
# Atomic Number: 30
# Atomic Mass: 65.39
# Horticultural-Benefit: 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.
# Deficiency-Symptoms: A deficiency of zinc will result in the yellowing of chloroplasts between leaf-veins, usually with purplish spots of dead cells on leaf-surfaces; older/lower leaves are the first to show symptoms. Vegetative-growth is retarded and deformed, and floral-growth is reduced. Excessive “Zn”-levels can initiate an “Fe”(iron)-deficiency.
# Element Name: Copper
# Symbol: Cu
# Atomic Number: 29
# Atomic Mass: 63.546
# Horticultural-Benefit: 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.
# Deficiency-Symptoms: A copper-deficiency can cause otherwise green leaves to adopt a bluish hue. Vegetative growth may fail to unfold, and may be yellow at the tips and edges.
