You are talking about making a self-seeding patch. First you must determine whether cannabis seeds will be killed by the winter cold in your area, which as I recall is more frigid than the stony gaze of a certain stern Secretary of State...
Look to commercial outdoor strains from the far north, ones with fat seeds and tough husks. If you are really serious about this as a long-term project, getting seeds from feral industrial hemp from a cold midwestern state and breeding a drug grade strain into it might be an option. And consider mulching your area very heavily each fall with a thick layer of leaf litter or hay.