you can do hydro outside.
Instead of using soil use a soilless mix like peat moss, coco fiber, a 50/50 mix of perlite and vermiculite, or any other soilless mix U can find...that means something that doesnt say "potting soil" in the title (ie. Miracle Gro Potting Mix has no soil in it, its peat moss, perlite, ocomote, and forest compost.) Just check the ingredients when U go shopping for a medium.
Also make sure that whatever you have doesnt have "Time Release" fertilizer or "slow release" fertilizers in it. (ie. Miracle Gro says it continuously "feeds up to 3 months" right on the label so you'd want to stay away from that bcuz it will take the control of feeding your plants on time away from you.)
But if you do plan on being away from your plants for days or maybe weeks at a time then you'd want to consider a slow release mix.
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But as far as building NFT, E&B flow, bucket systems - that will be kinda hard unless you got a location outside that has electricity and enough space for the systems.
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I really dont understand people who'd go thru all the trouble of planting outside if they are only growing 5 or less plants. It just seems to be a waste to take such a risk over a few plants. I wouldnt do it, its to cheap to buy the lights and fans you need for indoor growing to risk doing it outside.