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Thread: What are Macro-/Micro-Nutrients, and what is each responsible for?

  1. #1

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    Default What are Macro-/Micro-Nutrients, and what is each responsible for?

    What are Macro-/Micro-Nutrients, and what is each responsible for?

    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.

  2. #2

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    Smile help with nutrients

    can some one tell me what nutrients to get coz i just cant get my head round it all thank you

  3. #3

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    Quote Originally Posted by badboy View Post
    can some one tell me what nutrients to get coz i just cant get my head round it all thank you

    There are about 15 elements known to be essential to plant life. Carbon, hydrogen, and oxygen are absorbed from air and water. The remaining 12 elements are absorbed primarily from the soil, in mineral (inorganic) forms such as NO3- and K+. They constitute a natural part of soil that becomes available to the plant os organic matter decays and soil particles such as sand and clay dissolve.

    Soil elements that are necessary for normal growth are called nutrients. The elements nitrogen (N), phosphorous (P), and potassium (K) are considered major nutrients. The three numbers that appear on all fertiliser packages give the available percentage of these three nutrients that the fertiliser contains; and always in the order N-P-K. For example, 10-2-0 means 10 percent N, 2 percent P (actually, 2 percent P2O5), and no K (actually, no K2O). Fertility is often measured by the amounts of major nutrients a soil contains. Relatively large amount of N-P=K are needed for lush growth.

    Three other elements - calcium (Ca), sulphur (S), and magnesium (Mg) - are called secondary nutrients. Plants require less of these nutrients, and most cultivable soils contain adequate amounts for good growth.

    Six remaining elements are called trace elements or micronutrients. As their name implies, they are needed in very small amounts. Commercial soils contain enough trace elements to sustain normal growth. The trace elements are also present in manures, humus, ash, and limestone.


    The amount of nitrogen a soil can supply is the best indication of its fertility. Nitrogen, more than any other soil nutrient, is inextricably linked with the living ecosystem. Nitrogen is continually cycled through living systems: from soil to plants and back to the soil, primarily by the activity of soil microorganisms. Nitrogen is essential to all life. Nitrogen is a key element in the structure of amino acids, the molecules which make up proteins. These, and all other biomolecules, are synthesised by the plant. Chlorophyll, genetic material (for example, DNA), and numerous enzymes and plant hormones contain nitrogen. Hence, N is necessary for many of the plant's life processes.

    Cannabis is a nitrophile, a lover of nitrogen. Given ample N, Cannabis will outgrow practically and plant. Ample nitrogen is associated with fast, lush growth, and the plant requires a steady supply of nitrogen throughout its life. Marijuana's requirements for N are highest during the vegetative growth stages.


    P is a constituent of energy-transfer compounds such as NADP and ATP, and molecular complexes such as the genes. The energy compounds are necessary for photosynthesis, respiration, and synthesis of biomolecules. Cannabis takes up large amounts of P during germination and seedling stages. During flowering and seed set, Cannabis' need for phosphorous is also high.


    K influences many plant processes, including photosynthesis and respiration, protein synthesis, and the uptake of nutrients. Just as with P, K uptake is highest during the earliest growth stages. K is associated with sturdy stems and resistance to disease in plants.


    Ca functions as a coenzyme in the synthesis of fatty compounds and cell membranes, and is necessary for normal mitosis (replication of cells). Plants take up much more Ca than the small amount necessary for normal growth. Ca is not added to soil as a nutrient; is added to adjust the soil's chemistry or pH.


    S is a constituent of certain amino acids and proteins. It is an important part of plant vitamins, such as biotin and thiamine, which are necessary for normal respiration and metabolism. (Plants synthesise all vitamins they need.) Most soils suitable for growing marijuana contain plenty of S.


    Mg is involved in protein synthesis and metabolism of carbohydrates. Mg is the central element in the structure of chlorophyll molecules and hence has an important role in photosynthesis. Most mineral soils and commercial soils have a good supply of Mg.

    Trace Elements

    The trace elements (Fe, Mn, Mb, B, Cu, Zn) are particularly important in the coenzymes and catalysts of the plant's biochemistry. Many life processes, particularly the synthesis and degradation of molecules, energy transfer, and transport of compounds within the plant, depend on trace elements. Trace elements are not used in large quantities to spur growth, but are necessary in minute amounts for normal growth. Indoor soils rarely require an addition of trace elements.

    All the nutrients are needed for normal growth. However, most of them are supplied by the potting soil. Ca, S, and the trace elements rarely present any problems. For most growers, fertilising will simply require periodic watering with a complete fertiliser, one that contains N, P, and K.

    Application. Fertilising.

    To grow to a large size, marijuana requires a steady supply of nutrients. These can be added to the soil before planting or anytime during growth. Bulk fertilisers are added while the soil is mixed, as described in section 6. These include manures, composts, humus, and concentrated fertilisers, such as rose food. Once the plants are growing, never condition or mulch indoor soils with bulk fertilisers. they promote moulds and fungi and attract other pests to the garden. Concentrated fertilisers can damage the plants if they come in direct contact with the stem or roots.

    While the plants are growing, nutrients are given in solution; they are dissolved in water, and the plants are watered as usual. Soluble fertilisers can be either organic or inorganic (chemical), and come in a wide range of concentrations and proportions of nutrients. Two organic fertilisers are liquid manure (about 1.5-1.0-1.5) and fish emulsion ((Some fish emulsion may contain whale by-products.)) (about 5-1-1). Chemical fertilisers commonly may have 20-20-20 or 5-10-5, or may contain only one nutrient, such as 16-0-0.

    A 10-5-5 fertiliser is 20 percent soluble nutrients and 80 percent inert ingredients. a 30-10-10 has 50 percent available nutrients and 50 percent inert ingredients. There is approximately the same amount of N in one tsp. of 30-10-10 as in three tsps. of 10-5-5.

    Actually, you can almost use any fertiliser, but the nitrogen content should be proportionately high, and there should be some P and L also present. For example, a 20-20-20 would work fine, as would a 12-6-6 or a 3-4-3, but not a 2-10-10 or a 5-10-0.

    How much fertiliser to use and how often to fertilise depend primarily on the fertility of the soil and the size of the container relative to the size of the plant. Small plants in large pots usually do not need to be fertilised. Even in small pots, most plants do not need to be fertilised for at least the first month.

    As the plants grow, they take nutrients from the soil, and these must be replaced to maintain vigorous growth. During the vegetative stage, even plants in large pots generally require some fertilising, particularly with N.

    The rate of growth of indoor plants is usually limited by the amount of light and space, once adequate nutrients are supplied. At this point, an increase in nutrients will not increase growth. Your goal is to supply the plants with their nutritional needs without overfertilising and thus toxifying the soil.

    Most fertilisers are designed for home use and have instructions for fertilising houseplants. Marijuana is not a houseplant, and it requires more nutrients than houseplants. The extra nutrients that it needs may be supplied by the use of large pots and a fertile soil mixture. In many cases, you will need to fertilise only in the dosages recommended on fertiliser packages for houseplants. For instance, Rapid-Gro (23-19-17) is popular among marijuana growers; use one tablespoon per gallon of water every two weeks.

    A typical program for fertilising might be to fertilise during the fifth week of growth and every two weeks thereafter until flowering. Then discontinue fertilising (or give at one-half concentration) unless the plants show a definite need for nutrients. It is better to fertilise with a more diluted solution more often than to give concentrated doses at longer intervals. (For instance, if instructions call for one tablespoon of fertiliser per gallon once a month, use one-quarter tablespoon per gallon once a week.)

    Make sure that a fertiliser is completely dissolved in the water before you apply it. Put the recommended amount of fertiliser in a clear glass bottle and mix with about one cup of water. Shake vigorously and then allow it to settle. If any particles of fertiliser are not dissolved, shake again before adding the rest of the water. If you have difficulty getting all the fertiliser to dissolve, first add hot top water. If the fertiliser still does not completely dissolve, you should use another fertiliser.

    Never fertilise a dry soil or dry Soilless medium. If the medium is dry, first water with about one-half quart of plain water per pot. Let the pots sit for about 15 minutes so that the water is evenly dispersed in the pot. Then fertilise as usual.

    It is difficult to give instruction for fertilising that will cover all garden situations. You want to supply the plant with its nutritive needs, but overfertilising con toxify the soil. Fertilising according to instructions for houseplants (both in frequency and concentration) should not toxify the soil. However, the plants may sometimes require more frequent or more concentrated fertilising. A good way to judge the plant's needs is not to fertilise one plant, double the fertiliser of another plant, and give the rest of the plants their normal dose. If the unfertilised plant grows more slowly, or shows symptoms of deficiencies, then probably all the plant are depending on soluble fertilisers and must be fertilised regularly. If the plants receiving the double dose grows faster than the other plants, increase the other plants' supply also. On the other hand, if there is little difference among the plants, then the soil is providing the plants with enough nutrients, and they either should not be fertilised or should be fertilised with a less-concentrated solution.

    Because they are grown in a relatively small area, it is easy to overfertilise indoor plants. When plants are vigorous, look healthy, and are growing steadily, don't be anxious to fertilise, particularly if you have already fertilised several times with soluble fertilisers. Slow growth or symptoms of deficiencies clearly indicate the need for fertilising.

    (i take no credit for this information).

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  5. #4

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    Hello, name is James...
    Last edited by OrangeWidow; 07-11-11 at 10:43 AM.

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    Brilliant. Both the above text and the info on nutes!

  7. #6

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    great detail on nutrients and macro nutes i been reading none stop since joining this forum every thread i had the privilege of reading so far is excellent work very informative
    and concise my eye lids are tired and closing but i keep reading, this is great stuff very inspiring

  8. #7

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    Ask a PT what Macronutrients and Micronutrients are!

    If its the same for plants as humans then I should be able to work this one out lol!

    Depends how active the plants are?

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    ShaolinSmoke (09-06-14)

  10. #8

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    Nitrogen phosphorus potassium magnesium and zinc are all mobile nutrients and are able to go from transport from old leaves to new leaves to help deficiencies, so deficiencies of these will show on old leaves first!

    The rest are immobile and deficiencies will show first on new growth at the top of the plant!

    Knowing this helps to rule things out!

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    great info thanksd

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