In summer 2016 after first time on Pinterest, I found an article pinned by Prof. Dr. Willem Van Cotthem Bottle tower gardening: how to start.

We do not have a garden, but a balcony and so I started collecting bottles. After all, it took a while, since we do not need to be bottled water in Tirol (tap water is mich better) and my kids are usually also not drinking soft drinks - except that time they had a lot of Almdudler.

I took what I had: Some leftover wood plank, screws, and the newly collected bottles and rigged it up.

After that, I bought eight lettuce seedlings and planted one in each bottle filled with soil.

PICTURE

Watering at the top edge of the balcony is a bit adventurous. But the salad grew well and after about a week we harvested our first salad - just the outer leafs, so it can continue growing.

Eight plants were not much for a household of 5. It was more about fun than to farm.

After two month we went into holidays and our neighboor watered our other plants, but not this construction. So after the holidays we had a vertical desert.

I planned to collect more 2l Almdudler bottles over the winter and plan a watering system. This may work with a simple timer, but hey, we’re in 2017: What about using a microcontroller?

So the requirements:

  1. grid autonomous system: I have no power outlet outside
  2. pump out of a water reservoir: there no water tap outside
  3. water only when needed: so I need a soil humidity sensor
  4. switch off pump in case of an empty reservoir and signalize this (red light, buzzer, …)
  5. do not pump at night in order to not disturb neighbors