Plant Nutrition and Visual Diagnosis

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Plant Nutrition and Visual Diagnosis by Grat3fulh3ad

Plants use inorganic minerals for nutrition, whether grown in the field or in a container. Roots absorb mineral nutrients as ions in water. Many factors influence nutrient uptake for plants, plant nutrition is a term that takes into account the interrelationships of mineral elements in the soil or soilless solution as well as their role in plant growth. This interrelationship involves a complex balance of mineral elements essential and beneficial for optimum plant growth. To determine elemental plant deficiencies and nutrient problems, most growers rely on visual symptoms.

Essential and Beneficial
A plant is unable to complete its life cycle in the absence of the essential mineral elements. The function of these element is not be replaceable by another mineral element. These elements are directly involved in plant metabolism.

Beneficial elements are those that can compensate for toxic effects of other elements or may replace mineral nutrients in some other less specific function such as the maintenance of osmotic pressure. The omission of beneficial nutrients in commercial production could mean that plants are not being grown to their optimum genetic potential but are merely produced at a subsistence level.

There are 20 mineral elements necessary or beneficial for plant growth. Carbon C, hydrogen H, and oxygen O, which are supplied by air and water. The six major essential elements are called macronutrients. They are nitrogen N, phosphorus P, potassium K, calcium Ca, magnesium Mg, and sulfur S, and are required by plants in large amounts. The rest of the elements are required in trace amounts and are called micronutrients. Essential trace elements include boron B, chlorine Cl, copper Cu, iron Fe, manganese Mn, zinc Zn, and molybdenum Mo. Beneficial mineral elements include silicon Si, cobalt Co, sodium Na and nickel Ni.

Balance and Ratio
This chart demonstrates the ratios of the different elements present in different plants.


Average ratio across the chart is...
N : P : K : Ca : Mg : S
7 : 2.5 : 9 : 1.9 : 1 : 1
and according to Agriculture Canada: Report on Hemp,hemp extracts more nutrients per hectare than grain crops, removing about two to three times as much nitrogen, three to six times as much phosphorus, and 10 to 22 times as much potassium per hectare, owing to fast biomass production.

This chart is Cannabis specific and shows nutrient concentration recomendations in parts per million.


For many years, there have been a few people who claim that there is an ideal ratio of the three principal soil cation nutrients (K, Ca, and Mg). This concept probably originated from New Jersey work by Bear in 1945. It is generally accepted that there are some preferred general relationships and balances between soil nutrients. There is also a significant amount of work indicating that excesses and shortages of some nutrients will affect the uptake of other nutrients . However, no reliable research has indicated that there is any particular perfect ratio of nutrients.

For an example, in Wisconsin researchers found that yields of corn and alfalfa were not significantly affected by Ca:Mg ratios ranging from 2.28:1 to 8.44:1. In all cases, when neither nutrient was deficient, the crops internal Ca:Mg ratio was maintained within a relatively narrow range consistent with the needs of the plant. These findings are supported by most other authorities. A soil with the previously listed ratios would most likely be fertile. However, this does not mean that a fertile soil requires these specific values (or any other). Adequate crop nutrition is dependent on many factors other than a specific ratio of nutrients. It will rarely be profitable to spend significant amounts of fertilizer dollars to achieve a specific soil nutrient ratio.

While there is no perfect ratio, balance within the range of acceptable ratios is important. Otherwise antagonisms (interference of one element with another) will occur.


Nutrient Uptake
Plant roots require certain conditions to obtain these nutrients from the soil.
First, the soil must be sufficiently moist to allow the roots to take up and transport the nutrients.Sometimes correcting improper watering strategies will eliminate nutrient deficiency symptoms. Over watering can lead to macro and micronutrient deficiencies. As oxygen levels are inhibited by overwatering, root growth can be limited and water uptake slowed. Elements such as calcium are transported via waterflow and deficiency symptoms can develop rapidly on new growth. Also the inactivity of root systems due to saturated conditions can lead to inefficient uptake of iron or phosphorus.
Second, the pH of the soil must be within a certain range for nutrients to be release-able from the soil particles.


Third, the temperature of the soil must fall within a certain range for nutrient uptake to occur. The best example is the purpling that occurs in cool weather from the decreased ability to use phosphorous. Here is a chart comparing root growth and leaf growth for several categories of plant species.


Symptom Manifestation
The location of the initial symptoms of nutrient deficiency , whether it occurs on either new or old leaves, is a key to proper diagnoses. If symptoms appear on new leaves, the problems could related to iron, zinc, manganese, copper, boron, chlorine, calcium, or sulfur. If deficiency symptoms appear on old leaves, the problem could be from lack of nitrogen, phosphorus, potassium, or magnesium.

Chlorosis and necrosis are two terms which describe symptoms of disease in plants. Chlorosis means lacking green (chlorophyll). Chlorotic leaves are pale green to yellow or white. Chlorotic leaves often show some recovery after the necessary nutrient is supplied. Necrosis means that the tissue is dead. Dead tissue can be gold, rust, brown, or grey. It is dry and crumbles when squeezed. Necrotic tissue cannot recover.

Factors that can confuse diagnosis of plant nutrient issues include excessive top growth beyond the capacity of the root system to support, pesticide toxicity, aphid infestation, mite problems, certain virus problems, damage to the root system by insects, disease, or other conditions detrimental to the root system and its environment. Dry atmosphere or wet soil may cause the blade tips to turn brown. Brown leaf tips also may indicate a nutrient deficiency, but in this case, more tissue will turn brown than just the end tips.

It is also very important to note, that the best remedy for a deficiency is Not Always adding more of that element. Deficiencies result from a variety of conditions, usually one of the following: low content (not enough present), high or low pH, Toxic levels of a competing cation (too much of an element, which could interfere with uptake), root disease, over or under watering, and high or low temperatures.

Even under the best conditions, not all leaves form perfectly or remain perfectly green. Small leaves that grew on the young seedling normally die within a month or two. Under artificial lights, bottom leaves may be shielded from the light, or be too far away from the light to carry on chlorosynthesis. These leaves will gradually turn pale or yellow, and may form brown areas as they die. However, healthy large leaves should remain green at least three to four feet below the plant tops, even on those plants under small light systems. Under low light, the lower-growing shoots as well as the large leaves on the main stem are affected. Some symptoms of nutrient deficiencies begin first at the bottom of the plant, but these symptoms generally affect the lower leaves on the main stem first, and the progress to the leaves on the branches.

Disease and Deficiency
Organisms like Pythium feed on the nutrients in roots causing an inefficient uptake of minerals. Iron deficiency can occur if root rot pathogens infect the root system. Foliar diseases, particularly fungal diseases can cause chlorosis of leaf tissue, a direct reflection of harvesting nitrogen from plant cells.

Visual Diagnoses

Old leaves affected first
(mobile nutrients)

Type: primary macronutrient
A major component of proteins, hormones, chlorophyll, vitamins and enzymes essential for plant life. Nitrogen metabolism is a major factor in stem and leaf growth (vegetative growth). Nitrogen is a key element in the structure of amino acids, the molecules which make up proteins. . 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.
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.
Deficiency symptoms: Leaves turn light green to yellow or becomes necrotic and drop off; plants are stunted and secondary shoot development is poor. Usually there is a rapid yellowing and loss of the lower leaves that progresses quickly to the top of the plant unless nitrogen is soon added.
Toxicity symptoms (nitrogen): Plants are stunted, deep green in color, and secondary shoot development is poor. High N causes vegetative growth instead of reproductive bud formation.
Toxicity symptoms (ammonium): Roots turn brown and appear unhealthy, with necrotic root tips; plant growth is decreased; necrotic lesions occur on stems and leaves; vascular browning often occurs in stems and roots; severe chlorsis and stunting of new leaves are symptoms on some plants.
Ammonium toxicity is common in soilless media, in highly acidic media, and under low temperatures. High carbohydrate and potassium levels in the plant can prevent some of the toxicity symptoms in some plants.
Ammonium fertilizers tend to make the soil more acidic, and nitrate fertilizers tend to make the soil more alkaline.

Type: primary macronutrient
Necessary for seed germination, photosynthesis, protein formation and almost all aspects of growth and metabolism in plants. It is essential for flower and fruit formation. 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.
Deficiency symptoms: Growth is stunted and old leaves initially dark green; older leaves may turn purple. Leaves overall are smaller and dark green; red colour appears in petioles and stems. The leaves may also develop red or purple colour starting on the veins of the underside of the leaf. Generally the tips of most of the leaf blades on the lower portion of the plant die before the leaves lose colour. Lower leaves slowly turn yellow before they die. Very acidic conditions can dramatically decrease P availability.
High P in the plant can cause Fe and Zn deficiencies. High P levels in the soil can help to deter aluminum toxicity in very acidic conditions.

Type: primary macronutrient
Necessary for formation of sugars, starches, carbohydrates, protein synthesis and cell division in roots and other parts of the plant. It helps to adjust water balance, improves stem rigidity and cold hardiness, enhances flavor and color on fruit and vegetable crops, increases the oil content of fruits and is important for leafy crops. 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.
Deficiency symptoms: Leaf margins turn chlorotic and then necrotic; scattered chlorotic spots often occur on the leaves, and these spots may later turn necrotic. K deficiencies sometimes show on indoor plants even when there is apparently enough supplied for normal growth. Often, potassium-deficient plants are the tallest and appear to be the most vigorous. Starting on the large lower leaves, the tips of the blades brown and die. Necrotic areas or spots form on the blades, particularly along the margins. Sometimes the leaves are spattered with chlorotic tissue before necrosis develops, and the leaves look pale or yellow.
High amounts of K can cause Ca, Mg, and N deficiencies. High sodium can cause K deficiency.
High soil Mg can reduce K uptake, but it seems to occur only when the soil Mg saturation is in the range of 25% to 30%, or higher.
Numerous studies have looked at the possibility of using the K/(Ca + Mg) ratio to explain certain nutrition problems. While this ratio may be useful at some times, often there is no relationship between these cation ratios and crop performance.
High K levels can help against ammonium toxicity.
There is no evidence that K has a direct elemental toxicity. Excess K is more likely to be experienced first as an induced Mg deficiency. Next on the scale of probable high K damage signs might be induced Ca deficiencies

Type: secondary macronutrient
A critical structural component of the chlorophyll molecule and is necessary for functioning of plant enzymes to produce carbohydrates, sugars and fats. It is used for fruit and nut formation and essential for germination of seeds.
Deficiency symptom: Interveinal chlorosis on older leaves. Magnesium deficiencies also occur in mixtures that contain very large amounts of Ca or Cl. Symptoms of Mg deficiency occur first on the lower leaves. There is chlorosis of tissue between the veins, which remain green, and starting from the tips the blades die and usually curl upward. Purple colour builds up on stems and petioles.A plant in a pot may lose much of its colour in a matter of weeks. You may first notice Mg symptoms at the top of the plant. The leaves in the growing shoot are lime-coloured. In extreme cases, all the leaves turn practically white, with green veins. Iron deficiency looks much the same, but a sure indication of Mg deficiency is that a good portion of the leaf blades die and curl.
High sodium, K, and Ca can cause Mg deficiency.
High Mg can cause Ca deficiency.
Numerous studies have looked at the possibility of using the K/(Ca + Mg) ratio to explain certain nutrition problems. While this ratio may be useful at some times, often there is no relationship between these cation ratios and crop performance.
Very acidic conditions can cause Mg to be less available.
Magnesium toxicity's are very rare.

New leaves affected first
(non-mobile nutrients)

Type: secondary macronutrient
A structural component of amino acids, proteins, vitamins and enzymes and is essential to produce chlorophyll. It imparts flavor to many vegetables. 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.) Some water supplies may contain Sulfur.
Deficiency symptom: Uniform chlorosis first appearing on new leaves. Sulfur is needed for formation of chloroplasts (not part of chlorophyll molecule). After the plant is deficient for a long time it may be difficult to tell S deficiency from N deficiency.
Sulfate/sulfur toxicity symptoms begin as an interveinal chlorosis and scorching of the leaf margins, which gradually proceeds inward.
Excess sulfate-S (SO4--) can reduce the uptake of some anions such as nitrates (NO3-) and the available form of molybdenum (MoO4-). Excessive amounts of nitrates can also reduce the uptake of sulfate-S.

Type: secondary macronutrient
Activates enzymes, is a structural component of cell walls, influences water movement in cells and is necessary for cell growth and division. Plants use calcium to help take up nitrogen and other minerals. 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. Calcium, once deposited in plant tissue, is immobile (non-translocatable) so there must be a constant supply for growth.
Deficiency symptoms: Light green color or uneven chlorosis of young leaves; margins of young leaves fail to form (strap-leaves); growing points of stems and roots cease to develop (blunt end); poor root growth and roots short and thickened.
Very acidic conditions can cause Ca to be less available.
Calcium, for all practical purposes, is not considered to have a directly toxic effect on plants. Most of the problems caused by excess soil Ca are the result of secondary effects of high soil pH. Another problem from excess Ca may be the reduced uptake of other cation nutrients. Before toxic levels are approached in the plant, crops will often suffer deficiencies of other nutrients, such as phosphorus, potassium, magnesium, boron, copper, iron, or zinc.
Numerous studies have looked at the possibility of using the K/(Ca + Mg) ratio to explain certain nutrition problems. While this ratio may be useful at some times, often there is no relationship between these cation ratios and crop performance.
High Ca can cause Mg or B deficiencies.
High sodium, K, and Mg can cause Ca deficiency.

Type: micronutrient
Necessary for many enzyme functions and as a catalyst for the synthesis of chlorophyll. It is essential for the young growing parts of plants.
Deficiency symptoms: Interveinal chorosis of new leaves followed by complete chlorosis and/or bleaching of new leaves . Symptoms of iron deficiency are usually distinct. Symptoms appear first on the new growing shoots. The leaves are chlorotic between the veins, which remain dark green and stand out as a green network. To distinguish between Mg and Fe deficiencies, check the lower leaves for symptoms. Iron symptoms are usually most prominent on the growing shoots. Mg deficiencies will also show in the lower leaves. If many of the lower leaves have been spotting or dying, the deficiency is probably Mg. Mg deficiencies are much more common than iron deficiencies in marijuana.
Alkaline conditions, high P, high Zn, Mn, Cu, or nickel in acid soils, poorly drained soils, and other poor root conditions can induce Fe deficiency. Iron deficiency also results in reduced rates of growth. Very acidic conditions can result in iron toxicity.

Type: micronutrient
Involved in enzyme activity for photosynthesis, respiration, and nitrogen metabolism.
Deficiency symptoms: lnterveinal chlorosis of new leaves with some green next to veins and later with grey or tan necrotic spots in chlorotic areas.
Alkaline soils, poorly drained soils, and soils high in available Fe can induce Mn deficiency. High available Mn can cause Fe deficiency.
Manganese toxicity is a relatively common problem compared to other micronutrient toxicity. It normally is associated with soils of pH 5.5 or lower, but can occur whenever the soil pH is below 6.0. Symptoms include chlorosis and necrotic lesions on old leaves, dark-brown or red necrotic spots, accumulation of small particles of MnO2 in epidermal cells of leaves or stems, often referred to as "measles", drying leaf tips, and stunted roots

Type: micronutrient
Necessary for cell wall formation, membrane integrity, calcium uptake and may aid in the translocation of sugars. Boron affects at least 16 functions in plants. These functions include flowering, pollen germination, fruiting, cell division, water relationships and the movement of hormones. Boron must be available throughout the life of the plant. It is not translocated.
Deficiencies kill terminal buds leaving a rosette effect on the plant. Leaves are thick, curled and brittle. Fruits, tubers and roots are discolored, cracked and flecked with brown spots. B deficiency may occasionally occur in outdoor soils. The symptoms appear first at the growing shoots, which die and turn brown or grey. The shoots may appear "burned," and if the condition occurs indoors, you might think the lights have burned the plant. A sure sign of boron deficiency is that, once the growing tip dies, the lateral buds will start to grow but will also die.
High boron causes many cellular activities to be partially inhibited and the toxicity to mature tissues is not considered to arise from the disruption of a single process, but from the accumulated retardation of many cellular processes.
The range between a correct application rate, and a toxic one is not large, so it is relatively easy to apply too much boron. Because of this, it is very important to get uniform mixing and application, especially when applying in concentrated bands or foliar. Because of the slow transport of B in the plant, symptoms generally appear on the older leaves and consist of margin or leaf tip chlorosis, browning of leaf tips, which is quickly followed by the death of the affected tissue or defoliation. The critical plant level for toxicity can range from 10 - 50 ppm in sensitive plants and as high as 200 ppm in tollerant ones.

Type: micronutrient
A component of enzymes or a functional cofactor of a large number of enzymes including auxins (plant growth hormones). It is essential to carbohydrate metabolism, protein synthesis and internodal elongation (stem growth).
Deficiency symptoms: Interveinal chlorosis of new leaves with some green next to veins; short internodes and small leaves; rosetting or whirling of leaves.
Plant roots appear to absorb Zn and Cu by the same mechanism. This causes interference in the uptake of one when the other is in excess in the root zone.
it has been reported that additions of Mg can increase the uptake of Zinc.
High pH and high P or Mn can induce Zn deficiency.
Excessive Zn availability or uptake could just as easily cause deficiencies of other nutrients such as P, resulting in their deficiency symptom being the only apparent symptom, or could manifest as chlorotic and necrotic leaf tips, interveinal chlorosis in new leaves, retarded growth of the entire plant, and injured roots which resemble barbed wire.

Type: micronutrient
Concentrated in roots of plants and plays a part in nitrogen metabolism. It is a component of several enzymes and may be part of the enzyme systems that use carbohydrates and proteins.
Deficiency symptoms: lnterveinal chlorosis of new leaves with tips and edges green, followed by veinal chlorosis and finally rapid and extensive necrosis of leaf blades.
Acid soils increase Cu uptake and High pH inhibits uptake.
High Zn levels will reduce Cu availability.
Cu defiencies due to low content are very rare.

Type: micronutrient
A structural component of the enzyme that reduces nitrates to ammonia. Without it, the synthesis of proteins is blocked and plant growth ceases. Seeds may not form completely, and nitrogen deficiency may occur if plants are lacking molybdenum. Molybdenum is the only micronutrient that has increased availability as the pH increases.
Deficiency signs are pale green leaves with rolled or cupped margins.
Because of the intensity of interactions, toxic symptoms will normally manifest themselves as deficiencies of other nutrients (Usually Cu).

Type: micronutrient
Involved in osmosis (movement of water or solutes in cells), the ionic balance necessary for plants to take up mineral elements and in photosynthesis.
Deficiency symptoms include wilting, stubby roots, chlorosis (yellowing) and bronzing.
Some plants may show signs of toxicity if levels are too high.
Toxic symptoms are similar as is found with typical salt damage. Leaf margins are scorched and abscission is excessive. Leaf/leaflet size is reduced and may appear to be thickened. Overall plant growth is reduced.
Chloride accumulation is higher in older tissue than in newly matured leaves.

Type: micronutrient
Required for the enzyme urease to break down urea to liberate the nitrogen into a usable form for plants. Nickel is required for iron absorption. Seeds need nickel in order to germinate. Plants grown without additional nickel will gradually reach a deficient level at about the time they mature and begin reproductive growth. If nickel is deficient plants may fail to produce viable seeds.

Type: micronutrient
Involved in osmotic (water movement) and ionic balance in plants.
One of the negative effects of excess Na is that it reduces the availability of K.

Type: micronutrient
The demand for cobalt is much higher for nitrogen fixation than for ammonium nutrition. Deficient levels could result in nitrogen deficiency symptoms.

Type: micronutrient
Found as a component of cell walls. Plants with supplies of soluble silicon produce stronger, tougher cell walls making them a mechanical barrier to piercing and sucking insects. This significantly enhances plant heat and drought tolerance. Tests have also found that silicon can be deposited by the plants at the site of infection by fungus to combat the penetration of the cell walls by the attacking fungus. Improved leaf erectness, stem strength and prevention or depression of iron and manganese toxicity have all been noted as effects from silicon. Silicon has not been determined essential for all plants but may be beneficial for many.


Related chart demonstrating element availibility across a range of pH conditions. As you can see correct pH is critical in avoiding deficiencies.


Some more related charts and tables...
Also additional information has been edited into the first post...

Cannabis nutrient profiles by Mel Frank and pH Imbalance


Miscellaneous Nute Charts:




In the chart that has visual diagnoses which 'common names' correlate to them?
e.g. Twisting,Clawing,Canoeing..

Thank you Logic and Greatful:drink


Plant Deficiency

You can never have too many resources for diagnosing deficiencies in your plants. Here's another one I've found:

It's also important to remember that sometimes the deficiencies can be caused by too much of another nutrient causing a "lock-out". So that when your plant looks like it has a deficiency in one nutrient the actual problem is too much of another and no increase in the first one will solve the problem.

That's the main reason that I quit using bargain basement nutrients on my girls. I was always trying to figure out what was causing one problem or another when all I needed to do to completely avoid deficiencies in my plants was to just supply them with a nutrient system that was formulated to avoid those problems in the first place.

After just a couple grows with Advanced Nutrients I became a bit of a cheerleader for them, I have to say.


New here. Great info. above .... need all the help I can get.

A friend told me that the little tiny flies in my grow room are (don't quote me !!) mold gnats or fungus gnats.


Anyone using 'Zero Tolerance" products???




Hi I’m pretty new to growing and have a few questions and was hoping someone would be willing to help.

I have a 4 pot Wilma system with coco soil and was wondering what my watering regime should be. Should I be running the dripper system 24 / 7 or should I be watering in cycles?

Can anyone help?


i grow in coco with pumps in 48 ltr pots and have them feeding every 6 hours for 15 mins but you will have to look at the size of your pots and how much water per hour your pumps pump


Premium Member
thnx guys....

nice read......more people should read this..i think it would save alot of "lock-ups" and dead plant....from mis-diagnosis....thnx for posting....Qwon...


cool thank you logic, great and informative.

Thanks for the information. Smoke on late night tokers.!

Jalisco Kid

It would seem like that one misc nutrient guide with 10 ppm of P would give you roots as long as my dick. Bad formula to follow in my opinion. JK


Premium Member
first timer with a problem

my blueberrys are approximately 5 weeks and 7inches. the bottom leaves are beginning to yellow and die, some have big,brown,rust colored spots. could someone please advise.


another beautiful thread logic just amazing you should write a book lol i would buy it =P


top info,i would be still scratchin my ass and head if it wasnt for that piece- cheers from seamus in the uk


That's great! That's quite a very informative post. Thanks for Tony share.


OH yea,just what i was lookin for!!well done dudes!!so i thought my soil was supposed to be 6.5??the chart says 5.6-5.8?? a bit confusing /im half peat half coco w/dolo/kelp ect.. sooooo PH isss???????????check water runoff{using drops} or soil tester???
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