A so called plant factory is a closed growing facility which enables the grower to achieve year roung production of various vegetables. The plant factory utilizes artificial control of the climate, like light, temperature, moisture, wind and carbon dioxide concentrations for the plants. The plants growing without soil in hydroponic systems, which allowed the recirculation of the nutrient solution. The diversity of hydroponics and hydroponic area are increasing greatly worldwide. Inexpensive Low-Tec systems are available, using naturally available materials as substrate and the systems itself. On the other side expensive and highly sophisticated Hi-Tec systems are developed, using either inert substrates or advanced culture systems. Nowadays hydroponics are one of the most innovative crop production systems. Most of the systems are the basic for the new farming technique called “Vertical farming”, which allows sustainable plant production in multi-story buildings. The basic question is: What is the most suitable hydroponic system for a given situation? Hydroponics represents a self-regulated, sustainable food production system utilizing mechanisms similar to the mechanisms existing in natural ecosystems. There are many other convincin
