Soil, water, and tea questions

Quick(er) note; when mixing THAT volume of stuff into the cement mixer, making sure to get the items mixed thoroughly requires manipulating the angle of the mixer, whether wet or dry, thus the NEED for the visqueen patch over the opening being held in place by the bungee..

Also, adding the liquids (I use milk jugs for several reasons), requires alternating the barrel of the mixer side to side, and pouring controlled amounts at a time, as well as creating a 'pit' in the center of the mix, or it'll run all over the place... and others nearby will know it, as they'll likely hear extensive profanity coming from the general work area. Word.

The mix just written today fills ~17 Classic 600s when transplanting from 3" cubes (*Part of the objective over time, <as a matter of both convenience and lethargy> was to have ONE batch fill ONE box/cabinet. It unfortunately only does about 7 Classic 2000s, however. So I'll either need to be more patient, or buy a bigger mixer. This being America/the U.S., I suspect that tug-of-war will be won eventually by the 'bigger mixer' concept). ;^>)

Moose, I found this method to be helpful for me...and I realize you do not reclaim your soil, so please adjust my method accordingly. I reclaim 10 gallons of grow medium and add about 2.75 gallons of "new stuff" with each batch making about 2 cuft of reclaimed grow medium.

1. Load fresh aggregates: peat, compost, bark, perlite, calcined clay, earth worm castings, vermiculite, etc (about 2.75 gallons) ....

2. Load 5 gallons of used grow medium (1/2 the amount).

3. Mix thoroughly (1-2 minutes)

4. Load dry powdered amendments (fertility, nutrition, liming, mycos, etc)

5. Mix thoroughly (2-4 minutes). Stop mixer and with a scoop, reach inside drum and pull grow medium that is stacked at the back forward the front.

6. Load remaining 5 gallons of used grow medium (1/2 the amount).

7. Mix thoroughly (2-4 minutes). Stop mixer and with a scoop, reach inside drum and pull grow medium that is stacked at the back forward the front.

8. Add 1/2 liquid while mixing (8 ounces or so at a time)

9. Mix thoroughly (2-4 minutes). Stop mixer and with a scoop, reach inside drum and pull grow medium that is stacked at the back forward the front.

10. Add remaining liquid while mixing (8 ounces or so at a time)

11. Mix thoroughly (2-4 minutes). Stop mixer and with a scoop, reach inside drum and pull grow medium that is stacked at the back forward the front.

12. Mix thoroughly (2-4 minutes), stop and do the "squeeze test" (grab a handful of grow medium and squeeze it, verify that it holds it's shape with a little bit of ribbon action. Add more fluids if needed and repeat Step 11.

13. I store my grow medium in 20 gallon Brute trashcans and stick a section of 3" perforated drain down the middle to provide aeration while the grow medium "cures" for about 10-14 days.

BTW, I use a big aluminum food service scoop with a 38 ounce capacity, something like this--


It is easy to thrust the scoop inside the mixing barrel and pull out a good sized sample...do it a few more times and if each sample looks like the other--then you are good to go, imo.

A grow medium that cures with too much moisture is no bueno...not enough is no bueno. It's the Goldilocks method at this point.

Thanks Doc.

Despite the order of my ingredients, I typically would lay down a thin base layer of the Pro Mix, then add all of the heavier stuff (EWC, FFOF, etc), then add the perlite to the middle, and the remainder of the Pro Mix up top (Pro Mix helping to contain some of the airborne dust from otherwise exposed perlite), then the lime and nutes, etc., on the very top, but spread out nicely, and more concentrated over the area of greatest volume in the mixer. So the balance of the tumbler more or less stays in the position I started in (*Hopefully at a time I was clear-headed enough to keep the beater paddles inside the tumbler off to each side nicely.

To avoid obscene and unhelpful buildups of specific amendments or aggregates (esp. perlite) in the bottom rear of the mixer, I have the visqueen placed over the mouth of the tumbler with the bungee, and, trying not to temp gravity too terribly badly, while the mixer tumbles (dry or wet), and not tipping it -too- far forward, I tip it forward to ~ level, then back again, several times, 'spinning' the tumbler for several minutes in various positions.

When adding the liquid, I'd found that leveling some of the mix in the rear to the front and creating a small dammed pit in the center, similarly to your process, was helpful for the first addition of a gallon or so of mixed H2O. After that I would manually rotate the mixer to perhaps a 45-60 degree list to one side, creating a natural void or pit to the side of the material with a 'nest' lower than the mouth of the tumbler, & add the H2O to the extent that it was not able to flow enough to spill, let that soak in, then rotate the mixer the other way about the same angle off of plum, and repeat.

The heavier the mixer becomes with the liquid and soil, the more tension in holding the thing at an off-angle to pour another jug to the next side. It's at this point that the lip on the tumbler may render paper-cut-like injuries to the insides of the fingers if a person hasn't done this before and isn't wearing gloves.

Yes, my mixer has 'bit me' before...

I'll try recycling with something resembling your process a time ort two. I rarely let my soil cook, thus the use of the FFOF and the Amazon Bloom for more immediate nutrition, though recycling will allow some of the benefit of 'cooking' to occur by virtue of the living soil concept..

Holding back a bit of recycled soil mix would help a number of issues, including the wallet, not having to find creative methods of tilling soil into the ground, or burying it in the field when the outside temps are well below 0, etc.

Thanks again.

...or you could mix two batches...Overfilling a mixer. I keep it at a low angle and let it spill into a wheelbarrow, then just shovel it back in, throwing it to the back. For a good mix, it should be rolling around the barrel and not clumping up.
Actually I think I would premix the amendments, half them, then mix in half my peat.

Another option may be to rent a full sack mixer for around $65.

I thought mixers were supposed to make it easier?

I just throw about a half a bale of peat in a container with a few gallons of water let it sit for a few days, then mix it with a stick...

I add oyster shells first, cause you can see it mix into the media better, then I add my other goodies

Save the perlite for the last, cause once the perlite is in its hard to see how well everything else mixed....

if you are going thru the trouble of mixing soil, why are you buying already blended stuff like ffof to add in?

premier peat is only 10 bucks for 3.8 cu ft at home deep pockets

MrBungle said:

I thought mixers were supposed to make it easier?

I just throw about a half a bale of peat in a container with a few gallons of water let it sit for a few days, then mix it with a stick...

I add oyster shells first, cause you can see it mix into the media better, then I add my other goodies

Save the perlite for the last, cause once the perlite is in its hard to see how well everything else mixed....

if you are going thru the trouble of mixing soil, why are you buying already blended stuff like ffof to add in?

premier peat is only 10 bucks for 3.8 cu ft at home deep pockets

Click to expand...

A lot depends on volume and a lot depends on age. I have a mixer sitting here, but I just mix on top of a hard service using a flatbed shovel. Often it is a lot easier than using a mixer. If I was doing more than a bale, I'd probably do a lot of small batches in the mixer, throwing them all in the same pile.

I've used preblended soil before to add variety. Some growers prefer the coco base, I think especially if using nutes along the way. I don't like the coco, but it's a matter of style and I can't argue with many of the results they have.

Thanks h.h. and Mr.Bungle.

The FFOF is for an immediate boost to carry the mix through (as is the scant amount of Dyna-Gro Grow or other more immediate liquid amendments) until the slower-to-release organics kick in, as I don't have space or time to let the mix sit and activate/ferment.. BUT, I make sure to add extra Perlite and Pro Mix to the 'blend' in order to tame down the stout nutes in the FFOF a bit.

I think I get a pretty even distribution of amendments using the method described, though years ago I would tumble everything BUT the nutes, then tumble dry again a second time, -with- nutes, then add the H2O mixture, and tumble wet for a third time... Always ph-testing after the wet tumble, before dumping.

The mixer I'm using is at least a 5-cu ft. mixer on a portable wheeled stand. (*Made by Imer <??>. I'd have to dig out the manual from the filing cabinet to see exact volume, but the lbs. capacity rating is on the side of the motor, and is in the neighborhood of 275. It'll handle, I think(??), a couple 60 to 80-lb. bags at one time. Last time it was actually used for concrete was the ~18 bags I put into the foam-insulated-and-rebar-reinforced floor of my 5'x7' walk-in, wood-stove fired fish and meat smoker, probably well over 14 years ago... Perhaps longer. Another exercise in my tendency toward over-kill).

I've typically tumbled the necessary number of minutes (at least several minutes) in each phase, then dumped into a LARGE rectangular tote with a removable plastic-hinged lid that holds just slightly more than the full mixer (though not too much more), with minimal spillage (*Again, the bungee-retained 6-mil visqueen 'patch' over the tumbler's opening allows the tilting of the tumbler up to level and back to its normal mixing position, without it ejecting much more than mere flecks. Though a tiny bit more sometimes gets spilled when dumping).

Lately I've been dumping into a slightly-less-than 4' diameter kiddie pool. But the pool can't sit where it gets dumped into for long, without becoming an inconvenience. It does, however, provide a place that can handle the initial full mix, and a partial, incrementally adjusted second mix, to bring the volume of the pool up to being sufficient to do the 9 Classic 2000s. Then, just in case of any minor discrepancy in the two mixes (full and partial), I keep a point-tip spade nearby that's been dipped in a bleach solution in the utility sink, and do a minimal hand-mixing in the pool with that.

The contest has been to get the correct amount of soil for ONE batch for ONE full cabinet/box, and still have a good distribution. Achievable with 16 Classic 600s. Not yet achievable with the 9 Classic 2000s, other than as described immediately above..

Often times between tumbles, or when removing the visqueen 'door' to check the mix, I've reached in and combed through the mix with my fingers, finding any clumps of EWCs or peat, and breaking them up more finely. They're often near the front of the mixer, under no more than an inch or two of the mix.

I'll do that a couple times, and it comes out a pretty good consistency, though some of the items will try to clump a bit after being wetted, even if they were properly mixed & broken up.

I try to keep ONE variety of plant to a cabinet/box, so that as they achieve similar size after pruning, etc., (number of branches/primary colas, etc.), then the drying/cycling between feeding/watering for each of the plants in -that- box is relatively in synch with each other.

Much easier to test a few pots and note the relative moisture overall, then water the whole box, than to test each and every plant in there, from 'X' number of different varieties, for which the needs are often different.

The (mostly past) exception to this segregation of varieties has been when testing prospective strains.

Once upon a time, with 6"x6" pots, and 21 different seeds, it was just too much to sort through and tend to at once. A real pain in the ass in a smaller area. Different water and food needs for that many plants in one smaller area was NUTS!!

And testing 21 different seeds more or less at the same time was an exercise in futility. At the end of a week of post-harvest smoke testing, trying to answer my own questions about the properties of any given strain/hybrid/cross became nothing shy of ridiculous... .

Also, with poor technique years ago, I would sometimes get gobs of perlite, or caked EWCs in the bottom of the mixer, at the deepest pocket in the rear, around/below the tumbler's inside center, all gobbed together. The amount of tumble time, the order in which additions are/were made, and the manipulation of the tumbler's angle during mixing, all helped to solve that problem.

Now that I'm using the pool, I could probably convince myself to reduce the mix into fractional amounts, retaining the ratios, and mix smaller batches for more mixing room. I'm often less-than-rationally stubborn when it comes to changes in routine.

Moose, imo, your media is too wet if it is not mixing well.

Dry medium mixes easily, especially if you do things in "1/2 batches". That is, add 1/2 of your dry bulk aggregates, mix thoroughly, then add the remaining and mix thoroughly.

I stole pages/lessons learned from the kitchen, especially baking. When bakers make complex breads & pastries--they start mixing dry ingredients first (sometimes adding 1/2 first, mix well, then add the remaining 1/2) before adding liquids, a little at a time.

Maybe the moisture in you Fox Farms bag is causing the problem. But I do know this, mixing wet aggregates with dry aggregates is problematic and can cause things to clump up (EWC).

Two days ago, I mixed just over 80 gallons of my custom grow medium, requiring 8 batches (about 12.7 gallons each) and it took me 4 hours (including setup & breakdown, and a few beer & bong breaks). Of course that does not include the time to weigh out the 2 dozen nutrient/liming/fertility products I use. Instead of buying bags of "mixed fertilizer", I mix my own from individually sourced ingredients.

Good luck man!

Thanks Doc.

The Pro Mix and other dry mixes hydrate at different rates. Despite knowing the tricks for faster/more uniform peat hydration (i.e., drop or two of 'safe' phosphorous-base dish detergent per gallon of H2O), I've typically simply waited for the ingredients to arrive at a relatively equal level of moisture. Much/some of this hydration and equitable moisture distribution is accelerated by the tumbling.

The 'balling up' of the EWCs is limited (not the bulk of that aggregate or others, but a few chunks, ranging in size from 2-1/2" diameter, to little nuggets.). The rate at which the H2O is added likely contributes to this, as the peat takes a bit longer to absorb.

In the finished product, I test hydration via one of the classic moisture test methods; squeeze the finished product into a ball in the palm of the hand, and limited to no drops of water should fall (i.e., it should -not- perform as though wringing out a wet wash cloth), but when pressed lightly from the side, with a single digit, the formed ball should break apart/disintegrate cleanly with very limited pressure, while still feeling wet to touch.

The FFOF is not really wet, nor even damp to touch in the bag, but -slightly- more hydrated than bone dry. (*Long ago I once made the mistake of buying components from outdoor-stored pallets that had been left uncovered in the rain, and, especially with the poorly-stored EWCs, brought home a whole bunch of fairly expensive and unusable material that amounted to fungus-infected garbage. I didn't even put it into the veggie gardens outside, as it was likely healthy for nothing, so I dumped it at the base of one of my least favorite aspen trees in the woods; the balsam poplar I battle with. They'll win eventually, as I age and they continue growing at frightening rates, but I'll go down fighting the buggers.. chainsaws, meat smoker grease pans, infected garden aggregates, etc.).. ;^>)

I'll try breaking the mix into two or more parts, despite the factors of impatience, time and energy, and see what transpires. At this point, using the Classic 2000's, I'm beyond the capacity of the mixer to do a full 9 in one batch anyway, so aiming for 4-1/2 (+/-) per each will simply balance out the size of the batches, rather than one large and one fractional batch.

In the interim, I changed my mind and went with micro-dosing of the boron, mixing about 1/8 of a 1/8 tsp (about a 64th of a tsp), and added that with 1/8 to 3/8 tsp of the Sea90 (depending on variety of plant, with GTH#1 receiving less Sea90, and SLH receiving more). WB received neither of these items yet in her feeding.

* I concluded early in my reading and the above exercise re. boron, that a coke spoon for such additions might again find itself useful in my life, but for entirely different purpose than it did in the early '80s. ;^>)

In the case of the two that -did- receive this varying tx, there was a minor reduction in odor from the blooms. Not a vanquishing, mind you, but rather a notable but minor lessening.

Thanks again.

Two observations--

1. Limit your mix to be not more than 1/2 the mixer's barrel capacity. The capacity of my barrel is 5 cuft and I limit my batches to be not more than 2 cuft.
2. Reduce your moisture. Moist small clumps attract more particles and like a snowball rolling down a hill...small clumps become larger clods. Small clumps that drier (or not as moist as you have described) breakdown and crumble apart.

A hand trigger (not twist) hose nozzle works wonders when mixing. Use it in short, hard spurts to spray towards the top, the back, and the sides to keep stuff from sticking. If you just pour the water in, it will tend to clump.

For comparison purposes--I only add 64 oz of liquid (nutrients, inoculate with some pyrethrin to control unwanted soil critters) to each 2 cuft batch. The starting reclaimed medium is not bone dry...but neither is it "moist" (it will not hold shape when squeezed...whereas my end product will not only hold shape but will also show ribbons). So I dribble it in (8 oz or so) at a time...no hose action here.

It has been a while since I verified my air/water porosity ratios--but the last time I checked the air capacity was over 25% (on purpose) with higher than normal water holding ratio around 40% (due to the high water absorbancy aggregates I use). Air/water porosity ratios seem to have a way of changing when the selection and ratio of aggregates also change.

Thanks h.h. I can probably reach a hose to the mixer, though doing the H2O directly from the hose bib will mean not letting the water settle, or warm up any. I can allow it to warm in the tub, but the particulates (dead iron bacteria, etc.) will get past. We'll see.

Doc, what is the method for testing porosity?

I'll break my mixes into slightly more than half of the existi9ng volume, and do two equal batches.

But the ratio of amendments is what I -think- is causing at least some of the issues. That, and the changes in water and nute quality.

I dosed the WB with the sea90, mild dose of Thrive Alive B-1, and ~1/64 tsp sodium borate.

Like the GTH#1, there's a noted premature darkening of pistils this A.M. that may or may not be related. Les reduction in scent. And the GTH#1 is regaining any scent lost after that process. The SLH still has very limited prematurely darkening to pistils, and while the scent moderated a bit after the micro-nute sources above were added.. she's more or less as she was; perhaps mildly more developed in growth.. Though in the case of the SLH, unless her growth rate changes, I'm a bit concerned, in contrast to past efforts with her.

Mind you, the micro-nutes referenced were added about 3 to 4 weeks later than I recall reading of them being applied.

Overall, despite her early rebellion to the soil mix and higher N than typical, the GTH#1 shows the most impressive bloom development, despite spacing/leggy-ness, which was more profound earlier on.

Next feed for all three varieties will be the yucca extract to diminish salts..

Thanks again.

How to measure air/water porosity in containers is an easy process that will take a couple of days to complete.

There are several guides on the internet, but this one is the one I used...since it uses weight (instead of volume) in some of the calculations.

https://njaes.rutgers.edu/pubs/download-free.asp?strPubID=FS881

Essentially, you determine the following:
1. Bulk Volume (amount of water to fill empty container).
2. Total Porosity (combined air and water porosity).
3. Water holding capacity (amount of water held by medium)
4. Available Water capacity (maximum amount of water the plant can extract from grow medium).
5. Calculate Air Porosity (total porosity - water holding capacity)

Smart guys say the ideal properties for container medium should be:

Total Porosity: 60-75%
Water Porosity: 50-65%
Air Porosity: 10-20%
Available Water: > 30
Net weight: 70-90 lbs/cuft

And remember, when comparing different sized containers filled with the same grow medium, the perched water table at the bottom of the container will always be at the same height. Which means the air/water porosity ratios will change when using the same grow medium in different sized containers. It is not "one size fits all".

Thanks Doc.

Staked the SLH last night. She is still nice, re. stem structure, and not so much staggering at the mid or upper length of stem for that reason, but the stems were starting to get heavy enough overall that the bases were swaying over in a few cases.

The GTH#1's already staked due to stretching early on.

The WB needs staked next. Thinner stalks at the bases just above the roots than the other two, but still good structure overall. And only slightly behind the SLH in terms of leaning over a bit, but the trends has begun. The WB is especially pungent now, despite receiving the later-than-optimal micro-nute dosing.

GTH#1 is still the most content in appearance, as far as mid-green color, and minimal to no signs of either mag, calcium, or nitrogen discontent at the lower leaves. If I can get her dialed in re. soil, I strongly suspect she'll not only be the killer smoke that her test mother was, but a satisfactory producer as well. The variables (along with quality of stone) that many seek in a plant. Potent, productive, and a -good- quality of high.

All 3 varieties are now staked, with good spacing of colas.

Trichome presence, scent, and pistil-cluster density is good across the board, though the SLH has yet to achieve any length to her pistils that would convince me she's as happy as she might be. Her trichs, as stated, are among the best ever in being a specimen of crystalline crustiness.

There are minor amounts of mag and N def. which I assume is calcium-sourced, a product of phase of growth, as well as the relatively stout NPK, making themselves available beyond current rates of absorption.

None have put out incredible healthy looking pistils like GTH#1 has. Period.

I would guesstimate that I'm ~ 3-1/2 weeks (+/-) from chopping the first of any of the varieties in this throw.

I am overwhelmed by the options and ideas currently. I have -some- of the technical info from Slownickel's CEC Lounge thread (though haven't completed reading, let alone taking any notes from that), ideas from Dank Frank's water-only organic mix, thoughts and approaches from commenters in this thread and elsewhere, and ideas for tx-ing nute and other issues from other web pages that are relatively solid. I have also spoken briefly with organic gurus elsewhere, though those were less in-depth discussions than what can be found in the other listed resources.

I cannot take all of these 'roads' at one time. Some approaches can be combined safely; some not so much.

I am wondering about the wisdom or risks in (extremely) mildly top-dressing the plants with (langbeinte/sul-po-mag), and gypsum, in an effort to address ALL of the mild to moderate issues outlined and extend health right across the finish line to harvest.... 3-1/2 weeks to the finish line.... Seems dicey to me, but... who knows? Someone does.... I'm sure.

I've never done such a thing this late in the game, and I'm inhibited, though some of that is based in past experience, and some in not letting loose of old patterns/habits very easily.

Any well-founded and knowledgeable feed-back re. this query would be welcomed.

When I see mag def. now'days, despite an urge wo feed with Cal-Mag, I instead am more prone to feeding with straight fulvic and humic acids, maybe a mineral addition, and waiting to see if the absence of primary and secondary ferts lessens the symptoms, thus giving valuable clues.

As it stands, a finish without addressing the issues described, will still provide a goodly amount of some very nice herb. Then there's always the 'what ifs' of trying to reach a better end closer to perfection..

Meanwhile my mothers call for new soil and larger pots, and I'm in a minor quandary as to what to mix up for them. Modify the older moderate soil recipe and add some gypsum, while decreasing dolomite a bit, as well as slightly decreasing K, EWCs, and N at the out-set, then adding some langbeinite after a couple weeks or so? Probably the route I'm considering taking at this point.

I miss the days of having an unspoken, undefinable Zen-like relationship, wherein the plants are as content as I am, or more even, and the science and art of growing merged without struggle. But each struggle is also an opportunity to get beyond the ruts of sticking to old knowledge, and expanding.


Some times learning new stuff is just too taxing..... dammit!! And my mind doesn't work as well as it once did either.. ;^>)

Well, in the absence of any feed-back re. top-dressing with fairly minor amounts of gypsum and langbeinite with 3-1/2 weeks or so left until harvest, I took to the internet ... again....while drinking a beer and tending a smoker with a bacon-wrapped pork shoulder roast seasoned with minor amounts of thyme, garlic, white pepper, and a drizzle of honey, before adding the double layer of bacon to the top of the roast, pinned with wooden tooth-picks.. Made more necessary by the meat dept that took nearly 100% of the fat cap off the roast.. Ignorant bastards!!!

Anyway, it was in the midst of that, following the 9% abv brown ale that I said, "screw it" and mixed up a test batch of 2:1 gypsum and langbeinite.

If a guy's gonna' mess his plants up, he may as well be eating and drinking well, right??

Anyway, and being a bit more serious, I used 3/4 tsp of the mix to top-dress the WB, meaning about 1/4 tsp of langbeinite, and 1/2 tsp of gypsum. I believe when applying experimental approaches, especially better than half-way through flowering, it's best to tread lightly.. Though this application may be light enough to make very little difference.. we'll see.

I applied perhaps a quarter of that amount to a couple of mothers in much smaller pots last evening, and perhaps it's mere subjective perception, but I believe the H2O processing, (and therefore feeding/fert absorption) would appear to have stepped it up a notch or three; the one that was watered with the minor top-dressing (WB) is darned hear dry today...

I may be onto something.. or maybe -on- something.. but thus far, I haven't killed anything, so it's a decent day.

SLH's buds are improving in size ever so slowly, and still pungent and crystalline. WB is being her fussy self, putting out nicely elongated pistils, perhaps 5% of which show abnormal pre-mature darkening, thus the reason for choosing her as the initial guinea pig in this top-dressing experiment among the three varieties...

GTH#1 is still increasing in size, trichs improving daily, and the pungent nature is waxing and waning with the light and watering cycle.

Aside from those mysteries and experiments, it occurred to me the other day that it's been since last October or November that I last changed my Merv 8 pre-filter and carbon panels in the filter box, yet the area near the grow smells clean, despite the plants having a nice odiferousness to them when sniffind in the room itself.

Mysteries and questions abound.

I guess I'll check the smoker's wood supply, have a puff or two of GTH#1, and take a nap.

Any objections?

I didn't think so....

There probably are as many "top dressing" techniques in the world of Cannabis--as there are growers.

I operate on a principle of timing...determine how many days it takes for a particular input to breakdown/decompose completely, and then time it's application accordingly.

Since most organic inputs with a nitrogen level greater than 6% will usually decompose fully in 75 days or so, while those under 6% may take 2 growing seasons before they are fully decomposed (meaning there will be residual after harvest for us container gardeners).

Ask yourself, "what is the purpose of my top dressing?". For me, it is to replace some of the nutrients that were consumed while the plant was "vegging" (again using the 75 day rule) and to provide additional flowering nutrients, such that on harvest--the grow medium will have given its all (little to zero residual).

I apply my topdressing on flip day and fully anticipate that by harvest (70-80 days later) all fertility will be consumed. So when I reclaim the grow medium--it basically lacks all fertility, but still loaded with nutrients.

Now the $64,000 question...what fertility needs to be replaced, and what "flowering" fertility/nutrients need to be introduced. Since I incorporate many sources of calcium in my grow medium (gypsum, dolomite, oyster shell meal, calphos, bone meal, crab/lobster shell, etc), calcium is something I do not include in my top dressing.

Things that I do include are: Jamaican Bat Guano (1-10-0.2), Neem Seed Meal (6-1-2), Feather Meal (12-0-0), Linseed Meal (6-1-1), Soybean Meal (7-1-2), Potassium Sulfate Fines (0-0-50), Indonesian Bat Guano (0-7-0), Blood Meal (12-0-0), and of course Rock Dust (0-0.13-0.11).

As you can see, my top dressing is designed to replace what was consumed in veg and introduce a bit more "PK" for the flowering mode.

As an equalizer, I can feed a bit of liquid fish for an immediate N boost for flowering plants that need it...but, 36 days before harvest I stop all fertility and enzymes, 21 days before harvest I stop using all enhancers, and for the last 10 days or so, the plants receive a significant water deficit. On harvest day, most of my containers are light as a feather.

That's how Doc does it.

Natto.
Bacillus subtilis fermentation of soy meal.
https://www.ncbi.nlm.nih.gov/pubmed/25062659