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ajacstern2324 karma

It is still a mostly non-nutritive medium so nutrients can be fed in plant soluble forms which don't have to be decomposed by microbes like in organic soil / super soil / no till mixes (which I think is the exact opposite of the spectrum). Peat/verm can also be fed organically with microbes, but I was curious what role microbes played, if any, in a media where the nutrients are already soluble.

ajacstern2323 karma

Hi Dr. Bugbee,

Many nutrient manufacturers have separate nutrients for vegetative cycles and for bloom cycles, some use entirely different base nutrients, others use a different ratio of their base nutrients, and still others recommend adding a PK booster to their base nutrients. Some nutrient companies recommend using their enhanced PK nutrients for just a couple weeks during the transition phase, others recommend starting after ~4 weeks in flowering, some recommend to use their bloom nutrients as soon as preflowers form. Have you found a benefit from using enhanced PK formulas for flowering? If so, what application time and rates did you find the most effective? For reference, I am in hydroponics, coco coir specifically, so I have significant control over root zone nutrients. My current nutrient schedule is Jack's 321 which has an NPK of 3:1:4 with 50ppm phosphorous at full strength.

From my understanding, these plants accumulate P during their vegetative stages and can then move it into the flowers as necessary, I can see that this may cause a problem with plants that are sent to flower after a very short veg cycle, perhaps causing a need for enhanced PK fertilizers in those conditions.

I suppose this also depends on what the purpose of nutrients in plants are. Are we just trying to provide enough nutrients to avoid any deficiencies so as to not limit plant growth, or can providing additional nutrients above required amounts accelerate plant growth?

Thank you for doing this AMA!

ajacstern2322 karma

Ah I see, interesting. Thank you. It sounds like my fertilizer line up wastes some P during vegetative growth but provides a sufficient amount for late flower in that case.

If you don't mind me asking a follow up question, have you found that high microbial activity is important for non-nutritive mediums like hydroponics? I know you mostly use a peat / vermiculite mix so not sure how close / far that is to hydroponics. There is an argument between keeping a sterile reservoir (h2o2) or a reservoir with beneficial bacteria. My belief is that microbes are not that important when you are feeding with plant soluble nutrients as they plant can take them up as they are in the water without any bacteria needed.

I suppose kelp and fulvic acids also fall into this question somewhat, as they are often touted as chelators that make it easier for plants to uptake nutrients. However, kelp and fulvic acids may have other benefits than just chelation, most of the research on them is done by the companies that manufacturer them so it is tough to determine whether they are worthwhile additives or not.