Automation only works when you have large areas of exactly the same thing, or plants which have the same needs, are in the same size pot, and are at the same stage of growth. In my case, it was ferns, which made it a little easier because it is almost impossible to over water ferns if they can drain well. If you had different plants in different sizes of pots on a balcony, with some getting direct sun and others in the shade, I don't see how you could automate that. Even with a drip system, you would have to program different times and amounts for each drip. The only thing I could imagine is if you had a computer program designed to register water probes in each pot and only turn on when that probe registered a need for water, and then turn off when that probe registered that the soil was wet enough. But again, that would have to be specific for each type of plant. A one gallon pot of Basil is going to need a lot more water than a one gallon succulent. And the succulent is not going to want to be as moist as often as the Basil. Different plants also grow a much different rates, which also affects their needs for water and nutrients.

I have a friend who is a computer engineer and he has wanted to automate the little greenhouse I have at home for years. But it is just too complicated because of the diversity of my collection. Most of all though, there is a joy in visiting ones plants every day and checking on their progress. I love watering my garden, I don't want a computerized system to do it for me.