how much perlite to add....please give some input

[budblower10]

I have dug 2' by 2' by 2 foot deep holes. I am replacing native soil with Scotts Garden Soil mixed with regular potting soil (I took miracle gro garden soil back, i heard it burns roots). My question is: i also bought some perlite and spagnum peat moss. How much should i add to a 2'x2'x2' hole full of garden soil to give sufficient drainage? How much perlite should i add? How much peat moss? It seems like the bags are smaller than i thought they would be, but nonetheless, how much should i add? It doesnt really say how much to add. It does say its for containers, but i guess that doesnt matter right? perlite is perlite? I dont want to add too much or too little. I also bought some composted leaf humus that i will add, is this a good idea? Should i add one bag per hole? or what.... Also, with some containers i am using, how much perlite, peat moss and humus should i add? I dont want to over do the perlite or really any elements of the mix. Should i add gravel to bottom of 5 gallon bucket? I dont think i will but i want to know yalls opinions. thanks alot for the help.