I had a "Secret Garden" in a storage room in the basement of my house. It was a hydroponics system growing leafy greens and herbs. You can see an hourly photo of it below:
Click the above photo for a larger version.
There's usually kale, spinach, cilantro, parsley, and green onion growing. Sometimes dill and basil. It's currently not active this fall of 2024 because I'm planning travel.
Nutrient Film Technique
The garden uses nutrient film technique (NFT) to continuously deliver a shallow stream of nutrient solution to the plants growing in 2" ABS pipe. A submersible fountain water pump sends nutrients up 1/4" irrigation hose to each of the four pipes. The nutrients flow down the slope passed all the roots and return to the ~40 L reservoir. An air stone oxygenates the water. Two computer case fans ensure adequate airflow.
The nutrients are kept in a reservoir underneath the towel, which helps block light and limit algae growth:
Previous Garden
My previous system Helios Alpha could grow up to six plants. It's designed around a single 102 L plastic tote. It holds enough water to harvest lettuce once before refilling. After the initial setup, the system can be ignored for weeks.