Digging out a nice hole, and adding things like fresh, neutral soil, mixed proportionally with correct amounts of perlite, vermiculite, mabye a lil pea gravel (depending on how hard it is to treck in and out, and tote all this shit, which is a job in and of itself for the guerilla grower), dolomitic lime, greensand, a pinch of epsom salt, and a lil peat mulch will wok wonders for an outdoor ops that dont see daily, or even weekly visitations due to stealthy guerilla tactics... Peat helps to buffer surrounding pH, which outdoors, shouldn't be an issue, but the dol. lime also helps with this, as well as micro nute defs with CA and MG, and the small smount of epsom salt will help with any potential MG issues, as well... If u can just leave it vegging with a good pile of worm castings and fish emulsion(not the stinky kind), and some N-rich bat guano, and these other things, and then when seasons change and flowering approaches, u can drop by and add some P-rich bat guano, rock phosphate, and bone meal to the "pile" around the base, and MABYE repeat it once again before harvest time, you will have it made...