Don't bother with all the 3 part, 12 part, super growth .......... stuff that you see on the intraweb. Go to HydroGardens and you'll be fine and dandy. www.hydro-gardens.com
You have to buy the Calcium separatly. Get your Magnesium from you local walmart. it's just epsom salt. They will even tell you that.
After chatting with them this week I am going to order some of the beneficial insects from them, especially Nemetodes. They can be used in your yard as well. They eat ant larvae (yay!) I don't know about Missouri but FL is eaten up with ants and for use in the yard, pots and hydro sounds like a winner.