55gal drum of worms opened up here CD! I'll chew on this one paragraph at a time, and answer best I can...I may not be able to cite specifics, studies/research, etc but can speak to what I've seen here and experienced personally,... I think there's no definitive answers here, sweeping generalizations I avoid because they are often full of exceptions and conditional factors.... Furthermore, ALL the nutes are needed all the time, they all serve their purpose during the entire life cycle, some are just more important, in demand, etc. at different times as you noted...
The NPK ratios do follow a trend for genuine cannabis nutrients that I see. It's all about the ratio's, some wiggle room on this, but a veg' formulation is pretty clear, as is bloom... To the best of my knowledge most all veg' formulations will have significantly higher N content vs. P, K values, or near the same as N... I think much of this depends on how specific the nutes are made for target plants though... Dyna-Gro, a good co', has "Grow" that's so called all-purpose, and that's the key phrase there! That product is 7-9-5, which is OK for cannabis and a wide variety of other plants too... I use this for my orchids as a general fert. because it covers all the bases more or less evenly, best for most types that can bloom over several months. They do have other products much better for cannabis IMO, much more "biased" to the stages: Foliage Pro 9-3-6, and Bloom 3-12-6,... Years ago, there were a bunch of growers here using the Grow More brand Sea Grow all purp. 16-16-16 and it worked just fine (extra P doesn't seen to mess with things like extra N does in bloom stage), and switch to Bloom 4-26-26.. That is more like a bloom booster IMO, with such high numbers and big ratio differences, and always used diluted for both... Not optimal, but it worked!
Keep in mind, the plant can store quite a bit of the mobile nutes, so this lends some flexibility to formulations, and stability in the plants performance
within a certain range of course.... Also in play (for soil/soiless mainly, especially organics) the soil itself and the microbes are a reservoir, 'crobe's cycling uptake and release as well... So, this is why in part there's no specific right/wrong formulation for veg' and bloom
per se,...
This is why I love this place! We have many fine growers, and some of them are great nute line testers because their grows are otherwise consistent in other aspects, so minimizing those other factors,... Dabber comes to mind, though he's been a big GLN fan for a while, he has run other stuff, and will be with Prescription Brand nutes soon I think? And we know also that some folks do well with certain brands, not so much with others while another grower rocks that same brand... Variables, layer and layers of variables CD, makes for difficulty in assessing this,... There are scientific studies out there, but you'll have to fish for them and really understand the scientific methodology behind the models made for such testing, and analyzing the results... It's actually quite complex and difficult to keep all things apples-to-apples, to isolate individual aspects and test them against a control group (no small challenge on that either!)...
:smoking:
Now all this said, it's clear that nute co's are pushing marketing forces into the equation here! And as you've seen in Sick Bay, it's all too easy to botch things, juggling pH and trying to avoid defc's and/or toxicities! I'm not sure about these formulations and relatively low P numbers (like we see in MC)...are those two made for cannabis specifically? In any case, again it comes down to ratios, not necessarily total amounts (hence the need to dilute often depending on those NPK#'s).... I can't account for why MC has such low P, but I know from what I've seen here and experienced personally that low P at the wrong time will compromise both yield and quality (bud:leaf ratio), genetics and other factors aside... This is why many MC users are adding in PK boosters,
@Dabber I cited before elsewhere before...
Another example: I had a bad run with BioTabs, organic, outside photo's, when the Tabs had a sudden rapid breakdown pre-bloom, which burned tips, and then a few weeks later P defc. kicked in during initial bud setting... I noticed the flower clusters were smaller and kinda airy during this time, followed by the outward leaf symptoms of P defc. (plants will suffer defc. consequences well before they literally show it in the leaves)... I started up with synthetic
right-now available bloom nutes, PK booster actually (Open Sesame 5-45-19?) to try and fix that mess,... it was of limited help, some responded better than others, mainly according to their finishing speed; long term bloomers fared better than faster ones, and most ended up with inferior bud:leaf ratio's for what that given strain is known for....
I think all these variable factors are taken into account for most nute formulations, a shotgun blast approach to make sure that even with feeding errors, their product will still show well enough,... That said, don't go crazy with the K inputs, K plays entirely different roles in the plants vs P, one reason why you see all good formulations with plenty of K around... GLN is very heavy on K across their line-up! MC, BE, even Sweet Candy is loaded with it... Critical for terpenes like S, yes, but again too much is bad news as well; worse, the symptoms for defc. and toxicity are very close! I find I have to look closely at a growers total inputs first when I try to diagnose their problem plants... And this is why, anecdotally speaking, I recommend going to a bloom nute with even or higher P biased ratio than what BE offers,.. I think BE is better for finishing, after big P inputs are no longer beneficial... Those huge PK booster numbers, I'm dubious about how much effect they have past a point. Extra does help, but there's no definitive numbers to assign to this, as you have noted in frustration ! I use all of them at diluite rates regardless,.... Again, there are some peep's here who just fine with what seems to be off ratio feeds, and since I'm not a plant physiologist, I can't wrap it up in a nice ball of explanation for you, just offer some things to chew on...
you're welcome CD! I hope it made some sense,.. it's a mighty brainful if you want to dig for more dots connected and all that, but fortunately that level of knowledge is not necessary to grow fine buds! Truth be told, some of the best I know are actually quite weak on the science, but they learn the plants, nutes and all that plenty well to manage most things going sideways on them,..
