NPK Nutrients - What to buy?

Thanks for the responses all, I got something to work with!

Creepy Steve is always spot on with any questions like this or lighting Questions.

7-8-15 will do you good. Anything that comes out to a weighted average of those ratios is a good starting point... 6.0-6.5 pH, you'll want some sort of buffering additive.. then necessary ca/mg/s, which can vary by tap water... if it's relative to teh rest, the 7-8-15 will result in diluted ppms for a 1.3-1.5 mix - 128 N / 60 p / just under 200 k give or take + secondary nutes. dilution may vary, but always those ratios, if 1-part premixed. Might need a 10% drop in nitrogen in bloom. can try to boost p/k but probably see toxicities within 1 week of adding it. So, good to make soemthing with 2 or 3 parts you add separately... and MKP (monopotassium phosphate) can be used for p/k boost. Ca is problematic because it'll easily form a precipitate in high concentrations of it and S. This is why the order of how you add nutes sometimes matters. When diluted and typical concentrations for fertilization, it's not a problem to add some Ca. Calcium nitrate is a great, cheap option. Kills 2 birds with one stone in allowing you to easily manipulate N without impacting much else and providing a shit-ton of calcium that should be more then enough relative to an expected ebb and flow of N. Slightly isolating proportions of N and p or k can make modifying the recipe super easy. jack's, souther ag, masterbrlend, cropsalts, floraflex pro, ghe pro lin, etc all do it with N, but don't allow as easily modified p/k without a rising/falling tide on other components of mix. TSP mentioned above is an option, but i am apacing on the 'pure' K option... the TSP also adds 15% calcium or some large % near there. this assumes hydro/soilless context... add in soil's variable components, and you have to consider that when trying to guesstimate a weighted average of what you are providing relative to soil+fertilizer. As above, there are advantages to multipart mix. little tougher, but between trial and error experience and general gist of the math going on, makes for a shorter learning curve. first 10 days or so seed can power growth, but i like a half to 2/3rds strength charge and as the plant grows more vigorously, amp up to a 1.5EC mix, give or take. this along with 10% runoff waste will maitain steady equilibium in your substrate. If i go over this, i see toxicities. if i drop any component much lower, i see deficiencies... so, it's a well-ballanced on-demand mix relative to my environment, which will have a say in what works specifically for you. Observe and react rationally and you'll hone a mix that works on 95% of marijuana plants, if not more. I notice i have to drop N in bloom, but raising p/k just results in toxicities relative to the concentration i feed.. something i track religiously. It's a good starting point because any issues will be easily identified without coinciding problems muddying the waters. play mad scientist and see what happens.. don't assume because you add "product x" it actually did anything... without any comparison to baseline.. there is no such thing is a yield booster, for example.. you either feed it what it could handle or you impeded it with toxicities or deficiencies..

If you click on the drop down menu at the side of the page you will see a section that says nutrients. In there are all the different companies that sell products with half decent NPK ratios. For most people the grow schedules are to strong for autoflowers and sometimes photoperiod plants so they last a little longer then you'd expect. Beware some companies charge a fortune for their products just because the label looks cool, but you can pick the similar product from elsewhere.

@GrowingGrannie, is this not a common thing to do? Does everyone just buy pre-mixed and has a variety of NPK ratios? Thanks for the articles, I'll read them!

I don't know why you want to do this but ok... the BIGGEST thing you're not really going to be able to do is figure out how MUCH nitrogen or how MUCH potassium or how MUCH phosphorus you're actually adding unless you have a chem lab and can analyze the soil.... But... here are some articles for you: for adding more nitrogen: https://www.gardeningchannel.com/add-nitrogen-garden-soil/ for adding more potassium: https://growfully.com/add-potassium-to-soil/ for adding more phosphorus: https://www.gardenanalyst.com/gardening-how-to/soil-and-fertilizers/increase-phosphorous-in-soil/ Good luck!