The Importance of [P]hosphorus

squ1rrely

Well-Known Member
Part 2 of a three part on the N, P, and K of growing marijuana.

part one on Nitrogen
https://www.rollitup.org/general-marijuana-growing/187212-fresh-look-nitrogen.html

from SKUNK magazine
vol. 5 issue 3

by The Rev
veratim

N, P, and K (Nitrogen, Phosphorus, and Potassium). In the first one regarding Nitrogen I tried to impact how all the nutrients work together as a team and how being out of balance with your nutrient additions is even worse than not adding enough nutrients. One of the first stepping stones when learning to master all-natural growing. True Living Organics style especially, is getting the bigger yields, even in smaller container sizes. At first you will bet the quality, but your yields will likely fall short of expectations. Follow my advice and the yields will come.
I think it is very important that you wrap your head around the fact that cannabis cannot absorb a shitload of phosphorus (P) in a single feeding. Even worse, often times is the fact that it there is plenty of leftover P in your container-mix -especially as in liquid additions - this can lead to a plethora of problems, because it tends to bond up with other elements like iron and calcium especially, making them all unavailable. Potassium, zinc and copper can also be interfered with to some degree, with too much P regarding uptake/availability. So pouring on powerful liquid P nutrients is not the way and is absolutely counterproductive in my experience. You often see I mention Fox Farm's liquid Big Bloom nutrients. Take note regarding the very low numbers for the N, P and K. So this liquid is all good to use here and there and especially in compost teas, but jus dont go ape shit with it. The strongest I ever use it is in teas during flowering and I use no more than 1 tablespoon per 2 gallons of tea.

Giving Her the Big P
Phosphorus is very important, especially for root development and flowering; it is a huge factor for getting large yields in any style of growing. For sprouts, it is important to hav some P available to them, and this is best done in balance with a dry all-purpose all-natural nutrient with more even N, P, and K numbers, like 5-5-5 for example. Too much P, especially when in concert with a high pressure sodium light source, can often times give you much higher male ratios when sexing them; so just FYI - in my experience.
Using dry, all-natural nutrients to supply your plant with good sources of slow release, steady P is thee way here, my friends. I am a huge fan of the Bulb Food 3-8-8 (NPK) blend by Peace of Mind line. It is a good buffer for pH right off the bat and has the added benefit of the higher K number than something like bone meal would deliver. K is every bit as important as P when it comes to flowering so always keep that in your melon. The lower numbers are also good for the fungi in you soul-mix, because a P number over 8ish tends to inhibit your fungi if mixed globally into your soil-mix, like say steamed bone meal would be, with an NPK rating of 3-15-0; however, non-steamed bone meal is all good to mix in globally, it's just important to kno that it won't really start working for about 30 days or so. Non-steamed bone meal is a much slower release than the steamed versions. If you dont kno why u love to keep the fungi in your mix happy, you need to do a little reading up. These fungal microguys are on of the main forces when it comes to high P uptake by your plants, especially the Mycorrhizal fungus.

My Favorite Ways to P
A great way to detect a P problem early is to look at the upper (top) couple sets of leaves on your plant(s). Pay attention to the petioles and make sure they are not purple. Lower ones can be purple that's all good but if the upper petioles are purple, then it is more than likely you having some P uptake issues. Other possible causes are cold temps, like below 50F or so, and sometimes this coloring can be genetic, but not commonly. More severe P issues can resemble them starving, often lower larger leaves will look purple/reddish with yellowing. From the tips of the leaves to about halfway down, the edges of the leaves will turn brown and crispy, often curling upwards.
Things that enhance P uptake are, a well aerated soil-mix, warmer temps - specifically root temps - and last but by no means least, the active decomposition of organic matter in the presence of dry P nutrients. Optimum soil temps for the microlife are at around 80F or so, and my gro rooms usually run around 79F lights on; and never get colder than 65F during lihts off, unless I am trying to make the buds pruple at the end with an air conditioner bringing my temps down around 50F for the last few nights before harvest. ::I PERSONALLY DO NOT AGREE WITH THIS PRACTICE. IF YOU WANT PURPLE BUDS, GET IT IN YOUR GENETICS. DO NOT STRESS YOUR PLANTS ON PURPOSE FOR ANY REASONS::

Rev's Big P

In my container mmixes I obey some great rules for giving my baybees the big P, and I flower 3' plants in 2 & 3 gal containers. First thing I do is make sure my container-mixes are aerated, with a soil-mix full of Perlite, shredded bark mulch and white rice. Also, I don't compact my container-mixes - just a couple little shakes to let the soil-mix settle a tad and thats it. I also lay down a layer of bark mulch on the floor of my containers about 1" thick before anything else goes in. In a 3 gal container in which I plan to flower in, I would put down the bark on the floor, then I would add about 2 teaspoons of blood meal and top it all off with about 1 tablespoon of bone meal or my favorite 3-8-8 Bulb Food, then about a tablespoon of balanced nutrients like 5-5-5 (NPK). At this point I then water the dry nutrients down into the bark layer a bit and then I would add the soil-mix.
Another fact about P uptake when growing all naturally, is the fact that in the presence of actively decomposing organic matter, the multitudes of microlife make P (and K) much more available to the roots via the microlife's exudes full of acids and enzymes, which are majorly responsible for making a lot of P available - even P that is bonded up into insoluble compounds. With this in mind always, I always globally add some P nutrients that have low P values, like never above 5. I use high P bat guano (0-5-0) and soft rock phosphate (0-2-0), both lightly at about 1 teaspoon per gallon of soil-mix. The roots like to "find" P as they go, its seems to me. I also use some alfalfa meal along with kelp meal - mixed globally into the soil-mix . to hav some nice organic matter ripe for breakdown into wonderful humus; while the plant is growing in the container.
I always use shredded bark as mulch on top of my container, about an inch thick. This is essential, so don't even think this won't make a big difference if you are an all-natural grower. This way I can top dress along the way with some High P bird guano (1-10-0)and kelp meal as well about once every 2 weeks or so. You can also use bulb food in concert here especially if your pH is running lower than you would like. This way oyou have the P coming in right alongside the organic matter (the kelp meal in my case) so the P is readyily available, and quickly too! I tend to use my bird guano in local zones, and I spread my kelp meal around the top pretty well and evenly. Examples of my additions in a 3 gal container every 10-14 days would be something like, 1 level teaspoon of bird guano, and 2 teaspoons of kelp meal. Once I am halfway through flowering, I only use the high P bat guano (0-5-0) until 3 weeks before harvest. At that time I stop all top dressings except for the kelp meal. You can see how I keep that organic decomposition process constant with kelp meal top dressings. Alfalfa meal would work too, but i really like the kelp meal as my first choice here; especially for the K kicker it brings to the table. Note that al bird and bat guanos are notoriously low in K, a very important element always!

Have A "doctor" Look At Your P
Things that contribute to P troubles are waterlogged, compacted and/or cold soil-mixes/roots. Also, high levels of calcium (Ca), like you find in many tap/well/spring water situations, combined with a little too much P will start big problems more times than not. So adding additional P at this point jus makes things worse.
P gets locked out at pH ranges of 4.0 - 5.5, so hav a good soil pH meter for troubleshooting purposes. Good ranges however, I do not recommend having any soil-mix run avove 6.8 - magor problems with micronutrients and secondary nutrient absorption will happen running a higher soil pH than this.


hope u learned something :mrgreen:bongsmilie
 

pinkus

New Member
part three on potassium (K) coming soon:blsmoke:
thanx guys. glad y'all appreciate it
Just read the N article...it contradicts one of the big trends right now: molasses in late flower. Molasses is a big Mg source and it says Mg is the major cause of harsh smoke. Damn! That's gonna have me rethinking my last 3 weeks of flower.

thanks again, that info (if true) is worth it's weight in weed :eyesmoke:
 

squ1rrely

Well-Known Member
these are not my studies nor hav i conducted many of these practices. i personally run DWC indoors and only hav dirt around once a yr for outdoor clones. although many of these nutrient regimens work jus the same in hydro as soil, jus different applications. but the sources for this information are credible in many ways. and u can use all the chems u want as long as u flush and cure correctly.
 

pinkus

New Member
these are not my studies nor hav i conducted many of these practices. i personally run DWC indoors and only hav dirt around once a yr for outdoor clones. although many of these nutrient regimens work jus the same in hydro as soil, jus different applications. but the sources for this information are credible in many ways. and u can use all the chems u want as long as u flush and cure correctly.
Hell yeah, I know RC Clarke (where rev got the info) wrote the MJ Botany bible way back when.

I just went 100% organic maybe 6 months ago, so I'm learning new things every day. Rev uses white rice in his soil....talk about a cheap additive. :lol: I'm gonna do some searches on this.

You def made my day bro! :eyesmoke:
 

squ1rrely

Well-Known Member
well i'm elated i could help man. i too hav never ran straight organics and was thinking about running a few strains i hav through with them to see how they react. i dont kno much about organics so i'm going to overload myself with information before i begin to run any tests jus so i kno i hav everything i need to kno.

and like i said. keep ur eyes our for the potssium thread coming in the next couple of months.
 
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