jwildeboer, My balcony has a new mini remote fusion energy collector (solar panel) that charges the water pump unit that in turn automagically waters my plants. No app, no Bluetooth, just a simple standalone solution to a simple problem :)
The pump unit that charges its (removable and replaceable) 2400 mAH battery with the solar panel and pumps water to my plants on a predefined schedule, on top of the 25 Liter water reservoir.
Two tomato plants with drip units connected to the pump