I also grow outside in containers. Start with veg ferts until you see the first flowers, then switch to bloom ferts. Last two weeks befor harvest STOP and flush just water. Important advise : don't be to paranoid with fertilisers , I have ruined many plants by over-fertilise them. It's better to have an under-fertilised than an over-fertilised plant. Cannabis is quite a tough plant, needs little care, just don't neglect.
Last two years I follow this (in my opinion) very effective technique : I plant them in an already , kinda of a super soil, mixed up media which is basically soil enriched up with some organic "good" stuff such as guanos (seabird and bat) some worm castings, some sea weed, some coco soil and so. Actually you can find millions of recipes in RIU and then maybe inspired and create your most effective one.
Cannabis needs quite a little care and much more true interest in get to know really into her. And Ofcourse love & respect.