Hey guys, I'm having some trouble deciding what soil to use for my outdoor grow. Right now i have 5 young plants growing in miracle grow soil. I'd like to use another mix when I put them out on their own, because everyone talks to badly about MG. (seems to be working fine, although i know its not organic) I'm considering just buying some walmart soil and mixing in some extra perlite. Would it be ok to mix some seabird guano in with the soil to give the plants a little extra nutes? Is there anything else I should add? If i did decide to continue using MG, wouldn't the time release ferts be gone by the time they flower? On the bag it says they last 3 months.