You can mix it in with your soil per the label. Your soil sounds like a great blend.
Why don’t you water from the top? Bottom watering does insure against no dry channels if you wait for the level to be seen at the top as it rises thru the mix, but it’s also a PITA.
I work about a small handful into the top inch for a 2-3 gal. pot.
Good luck,
Uncle Ben
The “testers”? I have to laugh. Sheesh, with each new crop of newbies… LOL.
Been using Osmocote on all kinds of materials for 50 years. It’s nothing new.
UB
like OUB said it should say on the label, but here’s the data sheet straight from the website
personally I wait for seedlings to stop being so delicate and wimpy before top watering, just so I don’t accidentally float them around.
say @OldUncleBen I had a question for you. I was looking at the micros on the indoor-outdoor plus and I noticed it doesn’t have any calcium. Not a problem for people with hard water but mine is very soft. Do you have any recommendations for a slow-release calcium source to add on to the osmocote for those of us with soft water and and no obvious need for lime? Would gypsum over do it on the sulfur?
Their root radicle is 4" long by the time they pop the surface. Decades ago I did the experiment by germing a bunch of brick weed seeds and when they popped dump them out to inspect what’s going on.
That’s what I use. No, won’t be too much sulfur. Am half ass with it, adding a cup or so to a tractor bucket of mix I’m making. However, I reckon that cannabis is indigenous to NON limey soils, volcanic rich. Way to find out exactly what pot likes is to find a tissue analysis posted somewhere. For example, citrus tissue analysis reveals that it uptakes, processes the ions, in a 3-1-2 NPK ratio.
Dyna-Gro foods have Ca.
Here you folks go, this is a sample test result from a consultancy run by Jennifer Martin, famously of Harborside Dispensary and creator of the Bubbleberry strain:
And here’s the Ag Schools:
And here’s an Advanced Nutrients study on it:
PhosphorusMyth.pdf (1.0 MB)
Excellent! Thanks @Dirt_Wizard
Based on Table 1 essentially the NPK is around 4 - 0.5 - 2
Backs up what I’ve been preaching for years, cannabis doesn’t need much P.
Uncle Ben
I’ve recently recommended this to a coworker to whom I will be giving some plants. I might give it a go here real soon too. 
thank you both for the insight
I’ve been giving it to everyone that I give veg, flower, or cannabis seeds and plants to, I really think there’s no simpler way to get folks past the fear of killing plants than telling them the magic beads do everything and they should just water regularly and occasionally add the stuff I give them in old spice shaker jars, which is mostly Recharge, Maxicrop, or some micronized rock from a local place called Stoned Dust.
I’ve been giving people a $120 container garden recipe all spring from Lowe’s and Walmart:
Lowe’s:
$35 6cf bale of Sunshine 4 Pro Aggregate mix with mycorrhizae
$5 bag of river sand
Wal-Mart (online, free shipping)
$25 Wiggle Worm castings 30#
$12.50 for 4# Dr Earth Tomato and Veg 4-6-3
$14 Osmocote Plus Indoor-Outdoor 15-9-12 with micros 2#
$12 Alaska Fish Emulsion 5-1-1 32oz
$12.50 Earth Science fast acting gypsum 2.5#
$6 Bonide Insecticidal Super Soap (potassium salts with Spinosad 16oz RTU spray
$7 Bonide Bt Thuricide 16 oz RTU spray
And then either pickle/olive/etc 1-5g white buckets drilled out with some gravel in the bottom, or those panda film grow sacks that are dirt cheap. I keep telling people to just get this shit and mix it up and they’ll have no problem growing a buttload of produce or cannabis with it, with no issues and a soil mix that’s ready to use again next year no worries.
If they want more volume I just tell them to add some good double milled black mulch and a $6 30# bag of composted cow or chicken manure, and a bag of landscaping pumice, or just find leaf mold and more sand, or just double the Sunshine. Lots of options but I figured that having a basic recipe just over $100 that fills a patio or garden is a good start for a lot of people.
If they really want to go for it with a mineral-based living soil I recommend they add smectite clay like bentonite or Montmorillonite which are also known as Fuller’s Earth and are very cheap. And some greensand for glauconite, landscaping or aquarium pumice for silica and to aerate the mix back up, and basalt/granite rock dusts.
At that point you’ve got a nice peat base just packed with lots of nice clay, sand, and other minerals, with a time release salt fertilizer and a pretty complicated organic structure from the worm castings and Dr Earth mix (which is a lot of fish bone meal and alfalfa and other stuff all conveniently mixed and spiked with beneficial microbes and fungi) with a bunch of fish guts for microbe breakfast whenever you toss some in. Plus “forest floor products” from your (hot mulched) black bark and shit, and leaf mold if ya scraped some up from the woods. Pretty nice, powerful mix that should be lightweight but nutrient-packed, since oxygen plus water plus microbes and decay/weathering equals plant food, and the Osmocote is going to take things to the next level like some anabolic steroids.
Nobody’s gone for it that hard yet but I’ve basically drawn myself a plan to reboot my soil mix if I ever feel the need to do it, and it’s been a good thought exercise for getting my own garden together this year.
I was wondering if you only use the 15-9-12 and not the 14-14-14.
Also, how long does one application last?
I’m still trying to figure out a method which I like to use. In the past I used synthetics and they worked great. ATM I’m dialing in organics and I’m deciding on what I like better.
the 14-14-14 doesn’t have any minerals/micronutrients, just NPK. The 15-9-12 is loaded with micros (except calcium). The store variety indoor-outdoor plus lasts 5-6 months while the manufacturer sells big 50lb bags of various time tables
It seems like the indoor-outdoor plus is very organics friendly, lots of aquarium forums have old threads talking about using it because it doesn’t shock their fish
Yea like he said the one we use (consumer Osmo+ Indoor-Outdoor with micros) is a six-month release, but they make all different schedules up to a year plus release for commercial ag. The consumer one is great because of the micros and the NPK is a good universal/base nute and it plays nice with organics from the slow release (and maybe the micros?) but it’s also the right slow release for a season of growing cannabis or garden veg. Or you just reapply 2-3 times a year for perennials and houseplants.
There are two different commercial 15-9-12 Osmocote formulas with different release schedules:
The second one is what we buy on the consumer market as Osmo+
This post gives some research numbers on nutrient release if that helps:
I’m also trying to get into a mixed regimen of Osmocote for synthetic nutes as a boost to a healthy organic soil, thinking it will get me the best overall results. So far so good on the one that I have been trying it with, she’s outpacing everything else in the tent, but it’s hard to tell objectively because the genetics are definitely stronger/bigger.
And the thing that catches my eye is that we actually need more magnesium than phosphorus, and more calcium than potassium. Maybe for cannabis we should call it N-Mg-Ca?
@Dirt_Wizard thanks for even more info. lol
I think I’ll give Osmocote a try in a few grows, on both my cannabis and my veggie garden.
I think it would be a cool experiment to run a few clones all using different nutrients to see what the
differences would be. I’m sure someone already has done this in some way.
I’m trying the 15-9-12 out this year myself. I need to do a runoff test to see what I should ph my r/o water to….any tips?
Not sure! The manufacturer says it’s not effected by pH from what I can find, but here’s your rabbit hole:
“Osmocote controlled-release fertilizers are not affected by salinity, pH, microbial activity, water quality, or rain. Only soil temperature and coating type and thickness influence the longevity and release of nutrients.”
Thank you sir, you’re quite the info hound! Much appreciated buddy! 
I just got a bunch done this morning so here’s a research paper sweep up for y’all:
Osmo+ 15-9-12 for cultivating agave:
e.1431-ENG.pdf (1.1 MB) e.1431-SPA+.pdf (1.1 MB)
Osmo for feeding bioremediation microbes:
1-s2.0-S2666049023000026-main.pdf (654.4 KB)
@buckaroobonsai I’m in prime form this morning, buddy! So I think your answer might also be in here, my earlier post with the infographic that I just referenced about release rates and stuff? This is the Masters thesis that those research conclusions were drawn from, it’s available through the university’s digital commons:
Optimizing the Physical and Nutritional Environment of Unleached.pdf (3.6 MB)
