Smart Garden: Build a hydroponic irrigation system with an ESP32 controller

Makers who dream of home-grown vegetables and herbs despite little space should look at a vertical structure on the wall. With a photovoltaic cell, the system can be supplied with energy independently, while a connection to the house WLAN offers control options. Simple hardware store materials are sufficient to build such a hydroponic facility.

When designing the system, one is initially guided by nature: Plants only need light, air, water and a few nutrients so that they grow and build up biomass. As a side effect, sometimes fruits, leaves or seeds sprout that we can eat. Classically, growth occurs in the earth. It gives the roots a support structure, stores moisture and supplies the plant with nutrients with the help of microorganisms. Since this system is not closed, however, water can seep into the soil or wash out nutrients, and cultivation in soil is very space-intensive.

Photo of a flowering plant on the ISS.

Hydroculture experiments in weightlessness on the International Space Station

(Image: NASA)

Hydroponics therefore tries to create a closed water and nutrient cycle. Here the plants grow in an inorganic substrate such as gravel or expanded clay, which primarily serves as a support structure. The supply of nutrients and water is provided by a nutrient solution that washes around the roots. The nutrients are only introduced in the required amount and do not get into the environment. Since the water does not seep away, the water requirement is also considerably lower. Only the part that is withdrawn through evaporation and plant growth needs to be replaced. With the help of artificial lighting and heating, plants can be grown under extreme conditions, such as on the International Space Station or the Neumayer Station in Antarctica.

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