When I first got into growing I spent a lot of money on snake oil. I bought into the hype that I needed twenty different nutrients to grow great cannabis. Now I pretty much ignore anything that is specific to cannabis.
I read blogs by old ladies who grow roses and tulips. I pay attention to farmers who grow gigantic pumpkins. I look for the cheapest and easiest way to grow so I spend more time reading and enjoying life then tending to my plants.
I'll share with you what I use... To start seeds I get a dixie cup, fill it with MG seed starting mix, and lukewarm tap water. I add 10% worm casting powder that I get at Osh Hardware, and 15% perlite to help retain water and improve drainage. The worm casting isn't really needed but I did several tests with lettuce, peppers, cannabis, tomatoes, and weeds in my garden to know that worm castings make a significant difference. but 10% is all that is need. I also tried 15% and seen no improvement over 10%. At 20% my plants did worse.
After about a month in veg the bottom leaves start turning yellow, telling me I need nitrogen. I go to Home Depot and buy Alaska Fish Emulations for $5. Its nothing fancy but its 5-1-1 and has all the micronutrients my plants need until I flower. Knowing when to add your nutrients is more art than science. Each strain and plant are different so you want to learn the signs of nitrogen deficiency rather then going by a set schedule.
When its time to flower I go back to Home Depot and by whatever is on sale that has low nitrogen and high p and k. Yesterday I was at home depot and seen they had Alaska bloom feed. I've never tried it, but the npk looks right so I know it will work. Last year I used Kellogg fertilizer and was very happy.
Organic growing is easy. The only hard part is keeping your wallet closed and avoiding pesticides.