I recently decided to build a green wall to decorate one of my bedroom walls. Before I got far on that project I had the idea of building smaller green walls to go in my kitchen. Except these would be used to grow herbs and greens instead of ferns and other decorative plants. So instead of mounting felt pockets on a backboard, I've put together a design for a vertical hydroponics system.
I've looked at a few of the many hydroponics designs available and I think a nutrient film system will work best in my kitchen. I've constructed a few inexpensive prototypes and I've settled on a combination of off-the-shelf pipes, fittings, and framing that will hold 10-20 plants in ~1m² of wall space. The idea is that that space includes the lighting, the watering, everything.
Prototype v1 put plastic pipes into a wood frame, with adjacent pipes connected by hoses and 3d-printed fittings. The main reason I printed fittings instead of using off-the-shelf parts was that COTS pipe fittings are very large and heavy (and expensive). It wasn't long before I decided to ditch most of the printed parts and just drill and glue pipes together. I threw on an aquarium pump, some inexpensive energy-efficient grow lights, and some printed fittings to hold net cups in place, and I had 15 herbs growing in prototype v1.1.
This worked pretty well, with herbs growing slowly but surely, but I really wanted the system to be highly automated. When you're turning lights and pumps on and off and adjusting water chemistry manually, it's easy to forget for a day or two and damage your plants. And who wants a garden that requires you to be at home all day every day? So first I put together a power control board that turns lights and pumps on and off per a timed schedule. For the herbs wall I have lights running 16 hours per day and pumps running for five minutes every 3 hours. I'll adjust those as needed as the plants grow. The pump I have is obnoxiously loud so I'll need to find a quieter solution before I increase that duty
For chemistry control I bought some inexpensive conductivity and ph sensors and some small peristaltic pumps and connected those to another microcontroller that will automatically maintain chemistry when the watering pump are running. That should keep system v1.2 stable for a week at a time. (currently I'm replacing the water weekly)
Next up, once this has been running successfully for a few weeks and all the bugs are worked out, I'm going to build a more permanent, better looking v2. For starters, I need to change the spacing between plants. Then I need to build a structure that will contain everything, water, pumps, chemicals, control boards, inside a single object. And then clean that up and paint it so it can hang on the wall semi-permanently and have nothing but a single power cord coming out of it.