Upside-down planters are cool. The major weak point has always been keeping the plants hydrated, especially during the peak of summer while producing fruit. In the first year, with no special consideration for watering, my plants suffered due to my unwillingness to schlep water to the porch and lift it all the way to the top of each planter. I mean every day?!?! Come on. It was never going to happen.
Last year, I tried drip irrigation. I suspended a tank of water above the level of the top of the upside-down planters and ran a thin hose across the tops of the planters with drip nozzles. The problem was that I could never get the water balanced so the first planter would get the same amount of water as the last. I also had problems getting them to drip slowly enough to last all day. Most of the time, I would be able to keep them hydrated but there was a lot of waste as the the water would run through the plants after an hour or less. Going away for the weekend meant severe drought damage.
I made my own planters in the style of the planters named after a popular planet and marketed by a company with at least one trademark attorney, and that was the best thing to happen to my balcony. I could be relaxed about watering and my vegetable plants thrive. This year, I finally figured out how to give the hanging tomato planters a reservoir without adding weight to the planters and losing dirt volume. After setting up this system, 100% of the water is going into the plants. There is absolutely no run-off waste.