I am so bad at those things I usually just do not attempt any new things like mixing soil, or even fertilizer. If it ain't already mixed and in a bottle or bag, forgetaboutit.
I have just started doing a Cubits Database and that takes time. I have all my plants listed here on ATP so now it is time to work on Cubits. You may want to take a look at what I have been doing.
http://cubits.org/JBsPlants/
That is my home link and you can check out the database and store from there. Enjoy. Must get to work.