For many years, us growers have been taught that cannabis requires a shit-ton of P and K throughout their flowering cycle. Over the last few years, the laws around cannabis have been changing for the better across the world. This has lead to some large studies, funded by some deep pockets into the ideal nutrient requirements for specifically cannabis. So far its looking like we may have been wrong and cannabis doesn't require huge amounts of P and K throughout their flowering period.
Of course, as further studies are carried out and we learn more about this fascinating plant, the general consensus amongst the scientific community may change. My theory is that due to the lack of research targeting Cannabis, we've been left to figure things out for ourselves.
Fruiting crops require high levels of K to produce fruit and may also use higher levels of P as they transition into the later stages of flowering as P is required for fruit development. As we had no hard data, many just guessed that Cannabis must prefer a P & K heavy diet as they also produce large buds. That and Cannabis pulls a lot of P from the leaves as they finish their flowering stage.
The theory offered by Bruce Bugbee is that plants load up their seeds with P to ensure they have enough to begin life. Even if we're growing sinsemillia, the translocation of P from leaves and into buds still happen, but doesn't need to be supplemented.
Anyway, there's been a running joke around the Cannabis community for a while; CalMag for everything :). You got some yellowing, throw some calmag in mate
Considering that within a balanced system, Calcium is only required to be ~100ppm and plants shouldn't show signs of Mg deficiencies until Mg drops to around 15ppm, why do people seem to be sold on CalMag being the answer? To put the above into perspective, my tap water contains over 100ppm of Ca! Adding more won't harm the plants because Cannabis can tolerate much higher levels of Ca before experiencing issues, but I have all the required calcium to grow healthy plants straight from the tap.
If you've read any book around growing, you most likely have seen Mulder's chart? If not, here it is once again.
Mulder's chart shows the antagonistic and synergistic relationships between elements. So, let's checkout the above chart and follow the links.
P seems to be an antagonistic towards several elements including Ca. Hmm, so high levels of P could affect the availability of Ca. Notice that P also had a synergistic relationship with Mg. This is interesting for a few reasons, but focusing on the subject of this post, seems as if Mg is also antagonistic towards Ca. Now let's look at K. K has an antagonistic relationship between Mg, P and Ca.
Could we be causing more harm than good by adding PK boosters? Seems like by adding all that P and K, we might be throwing things out of balance? Then to correct those imbalance, we throw more salt at them
Could we just stop the PK boosters and the plants would be much happier? P is also very harmful to the environment so if we can reduce the use then it's a win win IMHO.What are your thoughts? Do you use PK boost? Have you noticed a difference between using and not using? I'd love to hear your thoughts.
I stopped using anything other than base nutes quite a few years ago and indoors I didn't notice any drop in density or weight from no longer using boosters , the only difference was my plants looked better without using them . The outdoor autos look so good but don't produce anywhere near what I can get with them indoors hence I tried pk this summer again, I don't think it made any difference so I probably won't use it again . With just base nutes the plants look happier so that's what I think ill stick to or maybe just using a small amount , easy t used .3 ml per litre on his last auto grow and his overall ec was really low something like .8 and his plant was bang on so I may try that on my next grow .
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