actually dude, using a compost, or organic soiless mix would be great to use for theoutdoors if its something your in to. N iMO, i would start prepping your grow area about a month before you decide to plant. Dig up all your soil, turn it all, and even take out as much as you want and replace with compost or soiless mix. the reason i say make it all out about a month before your ready to plant, is because it will make your mix blend in with the regular soil, and itll make the compost more rich with the natural nutrients of the earth. If you dont get much rain where your from, just water the compost every few days, and prep it, like you would your soil for an indoor grow, only for longer. make sure that you soften up the soil deep enough for a nice massive root system too.
The easiest thing to do when growing outside, would be to start from cuttings, not seed. thatll also give you something to do while your prepping the soil. just start your plants at the same time, top them once or twice during the month that youll have them indoors, and when your ready to plant, throw the bitch in there, and let the seasons pass.
i dont know much about outdoor growing, but i did read a 15 page article on it just the other day, n It was written by Marc Emery, pretty much step by stepping how he goes about setting up his outdoor grow ops. its a pretty damn good read man, its in this months Weed World mag. Go check it out if you want the play by play on how to prep, and grow outdoors.