Guide to Nutrient Deficiency or Toxicity

nick17gar said:

So 99% of the times I come in here to see what people are up to and check what forum threads I can throw some advice in, its plant issues.

"theres yellowing" or "leaf is dry and brittle" or "OMG SPOTS!"

so instead of using the 'cut and paste' tools, over and over all day, like I feel I have been, i figured id start this. Theres other stickies on here, but apparently people either dont read them, or cant connect their plant's issues to what those authors are describing.

*NOTE: to make sure your plant is getting what it needs, keep soil pH to 6.5 and 5.8 in hydro, otherwise, the nutes can be there, but the roots cant take them in*

Also, make sure if you notice a deficiency, please please PLEASE, dont drown the plant in that chem to save the day. your not superman. feed the plant. dont suffocate it! Slow changes are the best way to make sure you dont go from a deficiency to an abundance, and the inevitable burn.

So lets start with the basics, NPK.

Nitrogen: This element is everywhere, your breathing it in right now! For your plants, its key in the vegetative growth. It stimulates and powers the formation of leaves, strengthens the stems, and helps the chlorophyll production.

An abundance of this is rare during vegetative, but it happens with new growers that think more ferts = more plant (and your right, but to a limit!). To tell if you have an abundance of nitrogen, simply look at the plant. You want green leaves, but not a dark green -> black color.
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A deficiency of this causes yellowing of the leaves. its common during vegetative simply because the plant is using it up just as fast as your putting it in. It also happens during flowering sometimes because most flowering fertilizers contain little or no nitrogen, as this is not a key nutrient in that phase of the plant's life cycle.
Usually the deficiency will be noticeable on the lower part of the plant, on the older leaves. then, as it progresses it will move upwards towards the newer growth.
*unlike a magnesium deficiency, nitrogen def will start from the tips and works its way inward* (ill get to mag def later). Most of all yellowing of leaves is caused by this, and it will stunt growth severely!
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Phosphorus (P):
The 2nd element in our NPK ratio and just as important! So, whats it do? Root growth. This nutrient is essential for the roots to thrive, and big roots can feed big plants. Its key from the time the seed hits the dirt. it speeds up germinating, it supports vegetative growth by providing the roots to support it. Its a MAJOR nutrient in reproductive stages of the plant (yes, flowering). No phosphorus, no buds.

Abundance: too much can affect plant growth by suppressing the intake of iron, potassium, copper and zinc. (wierd huh? but yea, phosphorus abundance is generally followed by a zinc deficiency)

[if someone has a pic of P abundance lemme know and ill add it in]

Deficiency: Didnt i go over this? slow growth! slow leaf growth, slow root growth, slow germination of seeds, slow bud production, the edges of eaves will be brown. Even fan leaves, the plants solar cells, will be affected by this, turning them to a dark green, purple and blue color. (not the kind of purple you want.)
*Deficiency of this can be caused by low temperatures - below 50F/10C

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Potassium (K):
a.k.a. potash, this nutrient is key for the usage of carbs/sugars. This is key for sturdy/thick stems, small bushy plants and disease resistance. Its needed for all stages of plant growth, especially bud formation.

Abundance: this is pretty rare to notice, excess potassium usually isnt absorbed by the plants but can mess with levels of magnesium, manganese zinc and iron. This in turn leads to salt damage acid fluctuations and possibly a calcium deficiency

Deficiency: this has yellowing of leaves, from outside in, but with a dark green center vein, and curling of leaf tips, this is mistakenly diagnosed as nitrogen def or iron def a LOT. Stems and branches will be weak, easily broken. the plant may also stretch. *too much sodium (NA) can cause a potassium deficiency.

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Ok so thats the basics. Now on to the trace elements. Wonder why they call them 'trace' elements? and why you dont see ratios or percentages on how much of them to use? its becuase you dont want too much of them. you want them, but very very little.

Magnesium (Mg): this is a component of the chlorophyll molecule, it works with enzymes in the plant. Magnesium helps support healthy veins, and leaf production.

Abundance: Excessive levels will create a toxic amount of salts, that will inturn kill your leaves, and lock out calcium.

Deficiency: This is pretty easy to notice, green veins but fully yellow leaves. leaf tips can discolor and curl upwards. leaf edges can feel dry and crispy. the necrosis on the leaf will start at the edges, work all the way around the leaf. the tips will twist and turn, then the leaves will fall off without withering. *mag def is common with too acidic pH*
heres 3 pics of early-med-late deficiencies of magnesium:

early:
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later:
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Zinc (Zn): Zinc does a little of everything, helps in plant size production of leaves, stalks, stems branches... Essential component in enzymes and growth hormones. its key in the formation of chlorophyll. Plants that have a healthy amount of zinc are more resistant to drought.

Abundance: this is rare. it can cuase wilting and death in extreme cases. but usually, this wont happen.

Deficiency: Spotting, bleaching of spots between veins (commonly confused with iron/mag def). Usually appears on older leaves first. It will affect the tips of growing points on the plants. Small crops due to zinc def is common. Pale/greyish leaves will be apparent (check for a nice shine to the leaves, if they lack some luster, they might lack zinc!)

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Calcium (Ca): Strong bones, duh. no really. strong cell walls, cell division, and root growth (mostly the newer root hairs). Helps absorbtion of K. Calcium moves slow, and tends to concentrate in roots/older growth.

Abundance: Too much can lead to other deficiencies. this can be caused by clay soils, unbuffered coco/humus, or excessive lime in the soil.

Deficiency: First visible in newer growth, leaf tips will die, tips may curl, growth is stunted. there will be a weakness in stems/branches. underdeveloped roots, and bacteria problems can arise. *can be cuased by too much potassium/nitrogen* calcium deficiency is commonly mistaken for over ferting. its key to notice in these pics that early stages of deficiency appear in the serrated edges/tips of the leaves, but its not just a death/necrosis, its a small circular spots of death, not just burn marks. young leaves will develop dwarfing, a strap-like shape, and shoots stop growing and thicken.
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later, it appears all over the leaf, and becuase its usually on the older growth, many people think its bugs. (noobs.... do you see bugs anywhere?)
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Iro


happy growing!

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slownickel said:

Roco,



Eirearan
Hey dude.
Ok if cannabis was to be fed electrolights what do you reckon the outcome would be?[

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Tigerpaws said:

Any idea what could be ailing her?

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drfish93 said:

Can anyone tel me what the problem with this is???

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BecauseIgotHigh said:

plant looks calmag nitrogen tox, keep your ph perfect and see what happens then. Plant looks good from that though?


magnesium

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Roger A. Shrubber said:

at first glance i would say something is eating it. looks like leafminer damage, which is actually the small larvae of several different pests that haven't emerged yet. spraying isn't very effective, as they're inside the plant. do you have any insects like small flies around your grow room? using yellow sticky traps helps, and i've found that watering with a half strength dose of spinosad if they get bad helps knock them down a lot. they aren't the same as fungus gnats, but if fungus gnats like the conditions, so will they.

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