Four layer strawberry cultivation

In 2018 a vertical farming system was developed in a section of a glass greenhouse at Research Centre Hoogstraten. This system consists of 24 gutters: 6 rows with each 4 layers of gutters. In this system, the plant density increased by 350%. To compensate the light loss due to shadows of the upper layers, assimilation lamps (255 µmol m^‑2 s^‑1) were hung above each of the lower 3 gutters. Temperature, relative humidity and light quantities play a key role in proper functioning of the system. In spring 2020 this vertical farming system was tested for the first time with the assimilation lamps. Differences in light quantity and temperature on sunny days led to differences in the fruit pattern, yield and grading on the 4 layers. Layers 1, 2 and 3 where respectively 36, 35 and 24% lower yielding compared to layer 4. The proportion of small fruits was 7 to 15% higher and the number of misshapen fruits was 27 to 49% higher on the underlaying layers.