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proper ratio of n-p-k for cannabis etc

Discussion in 'General Indoor Growing' started by mikegreenthumb, Jun 2, 2010.

  1. GrowFAQ <GrowFAQ%20Basic%20Topics.html> :

    *ChristianKungFu - Basic Elements and Nutrient Balance (long)*

    Added by: snoofer Last edited by: snoofer Viewed: 256 times Rated
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    *Basic Elements and Nutrient Balance*

    Intro - N <#n> - P <#p> - K <#k> - Ca <#ca> - Mg <#mg> - S <#s> - Micros

    I suppose a basic introduction to the nutrients would be in
    may be common knowledge for many, so just skip on ahead, but like I once
    was, many are just getting familiar and knowing the basics makes each
    additional step that much easier to grasp. So hang in there!

    To start, here are the approximate ratios of elements generally needed
    by plants.
    primary nutrients
    secondary nutrients

    O, C, and H are provided through air and water mainly. We are
    responsible for the rest.
    Remember... this is a GENERAL approximation for all plant life, and
    cannabis, like any other plant, has certain and specific biological
    needs which call for some alterations to these percentages. There is no
    scientific standard on the proper ratios of these elements for cannabis,
    however it IS some agreement on the specifications for N,P,K during
    different stages of growth....
    This is also a generalization based on VEGETATIVE growth....seedling,
    flowering, and flush stages require different ratios..phosphorus being
    the obvious! But this is a good barometer for balancing your own fert

    As far as specific cannabis ratios for is a quick
    reference. (these are just ratios...not recommended fert formulas) You
    may find a number of different ratios presented by different 'experts'.
    Feel free to experiment, but keep a record of fertilizing, so you can
    judge results.
    Seedling 5-3-4
    Vegetative 5-2-3
    Flowering 5-5-3

    (Side note, many growers refer to N-P-K as macronutrients while
    referring to the others as micronutrients. This gives the impression
    that they aren't as important. While its true that most organics and
    some commercial soils have ample micronutrients...Ca, Mg in particular
    usually need to be added, hence the distinction as SECONDARY nutes.
    Sulfur often comes through various salts, so don?t worry as much. The
    micronute ratios are so small that variances aren't very significant in
    terms of maximizing yield or quality. As long as you have some in there
    you're good...and its pretty hard to OD on most micronutes as long as
    you aren't pouring it on!)

    Notice that the N and K requirements are very close. One mistake often
    made by us growers is to use a high N fert while neglecting K. If you
    use a 12-0-0, 5-1-1 or something similar, you NEED to supplement with K.
    Of course, then during flowering we boost the P and lower the other macros.

    Another reason the P,K figures are higher than maybe expected is due to
    a bit of trickery on the fertilizer labels of commercial products.

    The N figure is straight forward because N comes from organics or
    salts....almost NEVER in mineral forms, but because P and K come in some
    degree of rock/mineral form, much of it isn't immediately available for
    uptake by root system because the nutrients aren't in ionic form.
    Therefore, the label figures actually represent the amount of P2O5 and
    K2O (NOT the amount of P,K) available in the FIRST year.

    You can figure the ACTUAL amount of P by multiplying the label# by 0.44
    and the K amount by 0.83.

    For example, let's say you're using a superphosphate at 0-20-0. You'd
    think that meant 20% Phosphorous. But it really means that, by weight,
    20% of this fertilizer is phosphorous in MINERAL form of p2o5 available
    in the first year. The actual amount of ELEMENTAL phosphorous would be
    20 x 0.44 = 9% available phosphorous.

    This labeling gimmick is why growers are FAR more likely to overfert
    with N than with P,K and why we need a bit more P,K than usually

    After all that, for the sake of confusion, I'll just standard N-P-K
    format when posting formulas, and let you do the math if you really want
    to see exactly how much P is available.

    As a result of a phenomenon involving growers' increasing predisposition
    for urinating on their plants, I'll take a minute to touch on this.
    Basically, urea nitrogen CAN be a good source of Nitrogen, but I don?t
    advise this indoors in small containers. There are too many variables to
    consider and monitor.

    The problem with ureas is that they FIRST must be broken down into
    ammonium nitrogen THEN further broken down into nitrate nitrogen.
    Obviously this is a lengthy process so the grower must have a much
    better sense of timing and be much more accurate in the dosage because
    while nitrate nitrogen leeches out of soil, urea and ammonium N do not.
    Many growers do not see immediate gains from urea and mistakenly fert
    again leading to toxicity and pH nightmares.

    If you use piss and are happy with results, you're likely an expert or
    just damn lucky. Knock yourself out...but wouldn't advise it. If you
    insist on the golden shower, I understand that pine bark helps to
    facilitate the nitrification process making ammonium nitrogen available
    more quickly.

    That said, I would still STAY AWAY from ureas and ammonium....find a
    nitrate source. In addition to the above problems, I forgot to mention
    that if you use ammonium nitrogen ferts in the same medium as lime,
    ammonia gas will be produced, much of the N will leave the soil medium
    into the air.
    Nitrate sources DO raise pH, which can lockup nutrients, so using them
    alone may require some pH modifier like iron sulphate, but chances are,
    you will be adding other ferts which lower pH. I'll touch on balancing
    these later on.

    SODIUM NITRATE (Nitrate of Soda)
    is GREAT! Its about 15% nitrate nitrogen with no ammonium or ureas. Good
    pure source of readily available N. (Unfortunately, it is much harder to
    locate nowadays because of the Oklahoma City incident) It will raise pH
    by itself at about 1/3 the rate of limestone, so supplementing with iron
    sulphate would be a good idea unless you have an acidic soil. Only
    drawback is very high salt index. Be sure you have a medium that allows
    leeching and do NOT overdo this.

    Keep in mind, as you become more familiar with salt fertilizers, you
    will find a myriad of products and combinations. For example, POTASSIUM
    NITRATE is highly soluble and provides TWO key elements! K-45%, N-12%.
    The only reason I'd avoid it is because you'd have to supplement with
    more N during veg state anyway...and its high salt which leeches easy.
    There are other salt sources, but they almost all contain too much
    ammoniacal nitrogen. I use fish emulsion which is NOT a salt fertilizer!

    is my favorite...bit stinky but not as bad as advertised! I actually use
    it myself. Doesn't alter pH, low salt index, water soluble-- I love it.
    I know, its an organic source really, but its one that I can easily work
    in with salt fertilizers. The N-P-K ratio is usually around 5-1-1 and
    supplies a number of micronutrients unavailable in chemical ferts. The
    Nitrogen breakdown is about .5% ammonium-nitrogen and 4.5% water soluble
    nitrogen. You could use this stuff alone during veg, although I would
    supplement a bit with potassium. Then during flowering, you could still
    use sparingly if needed while focusing more on salt fert mixtures.

    Phosphorous helps to enhance growth and vivid colors, especially during
    flowering. It will strengthen stems early in growth and will increase
    blooms during flowering....pretty obvious why high P is so crucial
    during flowering cycle!

    Many sources of phosphate, especially those made to mix INTO the soil
    before planting, come from mined phosphate rock which has very little
    available P....remember, plants only uptake in ionic form.

    A whole thread could be written on the processes which make P
    available....I'm not an expert, so I'll stay away from the details.
    Basically, mineral phosphate deposits, taken from rock, are treated with
    acid or extreme heat, producing a salt fertilizer much more readily
    available to plants. Varying degrees of treatment result in various
    amounts of available P which is water soluble. Rock phosphorous is the
    beginning of it all...superphosphate and triple super phosphate are more
    refined....phosphoric acid...oh yeah.

    PHOSPHATE ROCK 0-3-0 has about 30% TOTAL available P, but only 3%
    available, in p2o5 form, in the FIRST YEAR...and that means about 1.3%
    elemental P.
    ITS takes FOREVER to provide nutes.

    Most SUPERPHOSPHATE is 0-18-0 and is about 85-95% water soluble. It also
    consists of about 20% Calcium and 12% Sulfur. be careful you dont OD on
    these micros.

    TRIPLESUPERPHOSPHATE 0-48-0 at 85-95% solubility. Also provides 14% Ca
    and 1% S. My fave...much more soluble and not so high a concentration of
    S and Ca...easier to control.

    PHOSPHORIC ACID is about 0-45-0 and 100% soluble.
    SuperPhosphoric Acid is 0-70-0 and 100% soluble....need I say these are
    HIGHLY acidic?

    AMMONIUM PHOSPHATE...11-48-0 ...also high pH...besides, remember
    ammonium N....yuck.

    Obviously, the ACID forms are the most potent and are convenient because
    they are completely soluble in water. However, you WILL DEFINITELY need
    to balance the pH. DON?T think you can avoid doing so or you will screw
    your efforts. Hydrated Lime is a cheap, easy way to do this. Don't use
    the lime with SP and TSP though...they already have high concentration
    of Ca and too much Ca will lock up K.

    I go with TSP over SP any day simply because it is much more
    concentrated due to better solubility and therefore more accurate PPM
    'guesstimate'. My current source of P is TripleSuperPhosphate can even increase the solubility a bit by grinding further
    in a mortar/pestle or coffee grinder...but I don't bother. Let it sit in
    a plastic bottle at the recommended dosage (if given) for a few days,
    even a week maybe and periodically shake it up. You can even siphon off
    the solution later and toss away the undissolved solids. Sounds like a
    pain in the butt, but just mix a large bottle ahead of time and save it
    away from light and air. It will last a few grows!

    Dissolve @10 grams/Liter in distilled water. Let it work, open to air,
    for about a week or so before using....swirl or shake it up a couple
    times a day. This allows the Chlorine in the solution to interact and
    dissolve into the air. That way, you retain the P ratio, but you reduce
    the potential for Cl overdose.

    Remember the formula<<<<<<<<< for PPM measurement? 10 grams in a liter
    would result in 4800PPMs of P if fully dissolved. So if you mix 5mL (1
    tsp) of this solution in one Liter of distilled water, you will have
    diluted the solution to about 24PPMs....15mL (1 TB) would result in 72PPMs.

    So lets try an example...Let's say you just entered the veg stage and
    you need a gallon of water to feed your plants. You want about 100PPMs
    of P in this solution. Let's work backwards.
    1 Gallon=3.79 if you want 100PPMs in a gallon, you need
    379 PPMs in a liter. We already see that per liter, 1TB=72 PPMs, so 5TB
    would raise a Liter of water to 360PPMs....convert back and get 94PPM
    per gallon (and 27PPMs Ca). Close enough!!!
    That's 5 TB of that solution per gallon water. I know my math is hardly
    conventional....sorry..........Yeah, I think we Americans screwed up the
    metric here's a conversion table.

    The only reason to use SP is because it seems easier to find in some
    places. However, it dissolves a LOT slower with much more remaining
    residue (remember the AVAILABLE phosphorous in year 1)...makes you
    wonder how accurate the PPMs are. have SOOO much Ca and S
    with mindful of other sources like Epsom, lime, etc
    Remember, these PPMs are ESTIMATES! get a meter to be's an
    investment. But one that will take you from quality to primo herb!

    Side note--you can lessen the chance of overferting with P ferts by
    making sure you have adequate potassium, which helps promote phosphorous
    metabolism into plant compounds.

    potassium is a bit weird. Its different from the other macronutrients
    because it isn't a component of basic physical foundations like
    proteins, fats, carbohydrates, etc. But it is crucial to photosynthesis,
    enzyme synthesis and other biological functions on molecular level.

    Because of its involvement in metabolism, K will influence dense buds,
    better yields, and resistance to pests and diseases....I think it may
    have some role in stem, root development, but cant remember for sure!

    Anyway, like Phosphorous, most potassium sources are derived from
    mineral the funky formula applies.

    During the veg state you want a formula with nearly as much K as N,
    while keeping P low...too often we focus too much on N. 5-1-3 or
    5-2-3...something like that. Its pretty hard to OD on Potassium. For
    those who actually care, the ppm limit is about 750...above this
    wouldn't be an OD, but salt damage would be likely!

    Remember, too much K will lock up Ca (and vice-versa).

    ...also provides 45% Cl, (I know those 2 figures don't add up but
    remember that means 49% 'actual' K)so don?t use other ferts with high
    Cl. You can let this sit for a while to let Cl dissolve just like TSP
    solution. Its pretty highly soluble...much more so than the pain in the
    butt SuperPhosphate! Watch the salt content of soil!

    also supplies 11% Mg and 23% S....Good thing is that this wont change pH
    much. But ya have to watch your other sources here so as not to get too
    much S or Mg...DO NOT use with Epsom salts (magnesium sulphate)...also
    be careful of limes with high Mg.

    High salt index so be careful, but it does leech easy if make a booboo

    also provides 18% not with SuperPhosphate or neutral!!

    I use Muriate of Potash 0-0-60 (Potassium Chloride)....a bag will last
    you decades...

    I find that with this product, 1tsp=5grams.....Remember the formula
    again....This time we are adding straight into solution first.
    For veg stage again, we want about 150PPM. We see that 1 gram of potash
    would be a fifth of a teaspoon...and would provide 600PPM per liter.
    That same fifth of a tsp would therefore provide 159PPMs per gallon.
    (600/3.79) Again, close enough!!

    Its normally best to introduce potash alone into water first before
    adding any other salts or solutions. The TSP solution and fish emulsion
    are already chemically dissolved (liquefied) so I CAN add them in same
    total fert mix with potash....but dissolve potash first!!...WORKS GREAT!

    *CALCIUM (Ca)*
    Calcium functions as a ?glue? in plant cell walls. It partially
    regulates cell wall permeability and works as an enzymatic cofactor

    Without Calcium, plant cells couldn't reproduce because it is vital in
    meiosis and mitosis, cell-wall permeability and enzyme synthesis. In
    addition to this role in cell division, on a larger scale, Ca is crucial
    to the growth of the apical meristem (growing tip). Toppers pay attention.
    Calcium is also important for seed germination...but that's not usually
    an issue. It also helps to neutralize acids formed during metabolic

    AND Ca helps promote P uptake as well as the uptake of Molybdenum
    (Mo)...a neglected micro. But remember, too much Ca can lock up Mg or
    K...high tolerance, but be careful, as always.

    Despite the importance of Ca, most pre-mixed chemical ferts do not even
    HAVE any Ca...your plant is missing out BIG time. You can tell too...the
    plant will actually look retarded or deformed in some way!
    Calcium primarily comes in salt form, so the percentages are straight
    forward unlike P and K...most of the elements are from here on actually.

    Now, the first few sources I list are limestones and aren't actually
    chem ferts....this is an example of some things I use in conjunction
    with salts. Limestones are great...most are aware of their great ability
    to raise pH and mainly turn to lime for this reason, but they also
    increases microbiological activity especially the nitrification process.
    There are different types, just read ingredients. Some have high Mg,
    some don't....look for high levels of Calcium Oxide/

    This is what I use....has 52% total Ca...derived from Calcium Oxide and
    Calcium Hydroxide and no other elements. 1 gram/L

    20-30% Ca, 10-20% Mg....raises a bit more gently than Hydrated
    Lime....seen a number of ranges.

    usually around 30% Ca and 3% Mg...Good choice if you can find it.

    This is the best for total control as it is about 70-75% Calcium with no
    other elements to balance.

    about 35% calcium but also a large amount of Cl...If you aren't getting
    chlorine source anywhere else, go ahead...its easier to get than
    CaO....Home Depot has it.

    And don't forget our old friends SUPERPHOSPHATE AND
    TRIPLESUPERPHOSPHATE....go back and look at those healthy Ca amounts!

    *Magnesium (Mg)*
    Magnesium is a central element of the chlorophyll molecule, so is
    obviously crucial to photosynthesis. It is also an enzymatic cofactor
    and has a role in uptake of many nutrients. It also helps seed formation
    for you breeders!

    Pretty Important which is why I like calling it a secondary rather than
    lumping in with micros. Look at most of those chemical fertilizers and
    you'll find a large number have NO Mg....that's why Epsom salts are so
    popular with growers.

    EPSOM SALTS (Magnesium sulphate)
    11%Mg, 2%Ca, 14%S Very versatile...some work into soil, but I don?t
    recommend this as they leech easily...might as well just add with water.
    Can also use as foliar feeder too. Good point is the neutral pH, but the
    main drawback with Epsom is high salt index. Don't use too much,
    especially in soil that dries quickly.......Its other drawback is the
    slightly higher S to Mg ratio. We actually want 3-4 times as much Mg as using Epsom, you are necessitating another Mg source to balance
    this....gets complicated as you need to be mindful of your other sources
    of S and Mg....don't overlap and OD!

    just look at the previous post for refresher....but be aware these raise pH

    60% Mg....nothin else...pure, great for specific deficiency treatment.

    10% Mg and 11%N....don't really see the point here...N is so easy to
    provide with other salts or ferts.

    supplies 11% Mg, 22%K and 23% S....this is a good balance if you need
    potassium...otherwise Epsom salts would be better...remember too much K
    causes lockup.

    *Sulfur (S)*
    Sulfur is crucial in the formation of plant amino acids & proteins, as
    well as respiration, cell metabolism. It also is an important part of
    good root development and the metabolism of fatty has a
    definite impact on the "bouquet" and taste of herb! Also keep in mind
    that S helps to regulate N uptake, so a S deficiency also inhibits N as
    (I've seen recommendations of N:S as high as 2:1 and 4:1. That seems
    high to me...check the list I presented at the top of this post. That
    would lead you to believe a 10:1 ratio is good for VEG doubt
    the flower state is higher due to Sulfur's role in protein synthesis and
    metabolism...I go for 5:1 or 6:1 tops, but again....start with
    conservative amount and work the dosage up...keep notes for another day!)

    Remember, plants can only uptake elements in ionic form, in this case,
    SO4. There are pure elemental Sulfur compounds available that only need
    to be oxidized for availability in plants. Obviously, water would serve
    this purpose....but an S overdose severely lower pH... its hard to do
    with most S compounds, but pure elemental Sulfur isn't real safe.

    Whatever you use, it does leech easily, so don?t let soil get dry and be
    sure to maintain a consistent S source THROUGHOUT the grow. If you use
    some organics, you probably wont need to worry much as they release
    ample S.

    11%Mg, 2%Ca, 14%S First mention because so common and for good reason.
    Provides two essential secondary nutes that often aren't found in
    commercial chemical ferts, and it wont alter pH the
    previous post... If you use it with restraint, you can supply a steady
    source of S through the whole grow and increase the Mg and Ca ratios
    with other salts.

    I like this stuff!

    provides 18% S....similar to sulfate of potash-magnesia, but TWICE the
    potassium (50%)...careful of lockup if you have K supplied another way.

    Good stuff, completely water soluble....20-25% S...WATCH the IS
    an acid

    Our good friends again....good product and I use this myself....only
    drawback is that preparation (see post on Phosphorous) is a pain in the
    ass for some who aren't used to their own fert. Remember gives healthy
    dose of Ca out if using lime!

    Stay away from AMMONIUM SULFATE...if you've followed the thread, you
    know why!! If not, well, Im high and you're just gonna have to go back
    and find out! CALCIUM SULFATE (GYPSUM) is very slow to
    release...wouldn't recommend inside for short harvest.

    I don't really bother to make a big fuss about micros because they are
    used by the plant in such small amounts, that either you have them in
    the soil or you don?t. If you go organic you'd have all the micros you
    need. I use fish emulsion for N source because of its micros. You can
    also use liquid iron, iron-sulphate or various 'citrus' ferts....they
    both have essential micros.

    I'm using a chelated "liquid iron" from ferti-lome. It has 0.05%
    copper(Cu), 3.25% Iron (Fe), 0.15% Manganese(Mn), and 0.16% Zinc(Zn).

    Some of the other liquid ferts can be used, but I find that the S
    concentration ts TOO high in proportion to Mg.
    Last modified: 15:53 - Nov 17, 2002

    GrowFAQ © 2000-2004 Overgrow
    faq:1347 "ChristianKungFu - Basic Elements and Nutrient Balance (long)"
    wesk, Zorlac, Chronic Monster and 2 others like this.
  2. not mine so dont ask me about or flame me over just found it wanted to share I FOUND very helpful and precious info
  3. tried to give you rep for this mike but site say i gotta whore out some more before i can give to you so ill say nice info in this post instead, so... nice info dude.
  4. thanks bro appreciate that yeah i came across it trying to figure out what issues were in my growroom and thought i would share

  5. looking good
  6. thanks bro
  7. Gro


    thanks for the post MGT.good lookin out.
  8. Great info man keep up the work people like you makes things easier
  9. no problem man
    just trying to contribute
  10. interesting that the author suggest 3-1-3 as the proper ratio. Everything I've been reading lately says the proper ratio is 3-1-2 or 3-1-4 - and that is all the way through from veg through bloom.

    that's for pretty much all plants

    I attached a file for folks to read. edit: I should probably mention, skip to the part about Tom Ericsson (sp) on page 3

    scope this thread too:

    Attached Files:

  11. My mistake, I read this quickly and thought it was the author's recommendation

    the 3-1-2 and 3-1-4 ratios are based on plant tissue samples and fatman7574 claims to have tested cannabis.
  12. he suggest as base and for you to find what works "best for you" and it also said how to factor in what is actually obsorbable alot of shit in nutes isnt readily there for plants slow release so factor that in your formula as well
  13. ill follow this = )
  14. doesnt even mention calcium nitrate lol.

    this was an interesting read, but the dude who wrote it is a weird o haha