Billyboob

I found a 5lb bag of this stuff in my garage however it states that it's for acid loving plants so im guessing a pH somewhere between 3.5 and 5.5? So i was wondering, like you add basic to acidic and it comes out even when your dealing with water's pH, will it work the same for soil? I'll probably go to home depot or something and buy some good ferts if i get the chance but if im in a pinch would mixing pH in soil work?

It's between the holly tone (4-6-4), miracle grow ferts (28-8-16) which i'd rather not use, or something organic i pick up at a store. Plants are only 5 days old so im in no rush.