Gonna take the time to repeat a discussion we're having on plant nutrition at another site, something which I've been preaching for years. Here are the posts:
UB opines:
- "Found the same experience HB, that every time I hit them with a high P food during flower, bang, there goes the leaves. I stopped that practice a long time ago."
REJ opines:
- "i just have to re post this one more time: from
http://forums2.gardenweb.com/forums/load/contain/msg0412411532471.html
Some of you may recall that I have long maintained that high phosphorus(P) fertilizers are pointless.
I also am a fan of Dyna-Gro fertilizers for container usage.
I was asked recently 'If high P fertilizers are so useless then why does Dyna-Gro make and market them?'
My answer was simply to have a product that people wanted, but that was just my opinion. I decided to ask the company (Dyna-Gro) about this. At first I got a very brief response from a representative that wasn't at all satisfying so I asked that rep to forward my question to someone responsible for deciding what their formulations would be. I ended up getting a response from the CEO. Here it is, I think you will find it interesting.
*******************
You are correct. We market a high P (Liquid Bloom) "believe" they need this. As you have noted, our Foliage-Pro does a great job start to finish. However, it is simpler to give the market what they think they need than to try to reeducate it. There is some evidence to believe that low N helps to convince a plant to stop its vegetative growth and move into its reproductive phase (flowering), but environmental factors are probably more important. P is typically 5th or 6th in order of importance of the six macronutrients.
There is little scientific justification for higher P formulas, but marketing does come into play for the vast majority of users who lack any real understanding of plant nutritional requirements. Therefore, the market is flooded with a plethora of snake oil products that provide little benefit and can actually do harm. For example, one exhibitor at a hydroponic trade show had a calcium supplement with 2% calcium derived from calcium chloride. Can you guess what continued application of 2% chloride would do to plants?'
I hope this answers your question and am sorry for Zina's inaccurate response.
Cordially,
Dave Neal, CEO
Dyna-Gro Nutrition Solutions
2775 Giant Rd.
Richmond, CA 94806
800-Dyna-Gro, Fax: 510-233-0198
[email protected]
www.dyna-gro.com"
Editorial comment - I've been trying to educate the cannabis forum community going on 15 years, and with every new crop of noobs, they fall for the same old snake oil crap....with such low N products ironically working against the grower because they WILL induce leaf necrosis, not maintenance.
Discussion continues........
Lumi opines:
"Sounds just like UB AND RM3. They have been saying this repeatedly. And most of the dumbasses argued on and on without ONE SHRED of evidence to support high P. now I did find good response from P-K boost last week to two weeks of flower. But one needs to keep in mind that it is a stress response not a health response
Also I feel it is the added mag and sulfur that helps in flower from mag pro not the increased P"
HB opines:
"There is a table on the second page of this paper that shows mineral elements in crop plants and their concentration levels on a dry weight basis. Sure enough, P is basically last out of the big 6.
http://www.pnas.org/content/91/1/11.full.pdf "
UB opines:
".....and so goes the cannabis growing community. Been saying it for years. It's refreshing to hear it come from the manufacturer themselves.
I had this same discussion with Jack Peters a while back. He admitted that the <30> in their bloom food, the 10-30-20, was functionally too high....just wasn't
required by the plant, but it's what people perceive plants needing.
UB"
UB opines:
"Nice job. If one was to analyze the dry matter in that PDF chart, on the low end of macro nutrients (and playing games with the decimal point on all 3 macros) you'd have a 5-1.5-8. At the high end of that range you'd have a 6-.5-8"