Besides the basic elements N and P, also K (Potassium) is crucial for every cultivation. Potassium makes for the sturdiness of cells (water household), and prompts the blooming. Potassium also plays an important role in the forming of cells, the osmoses regulation and the carbohydrate household. Furthermore, potassium is important for the opening and closing of the stomata, which enable the drainage of excessive heat. A deficiency of potassium manifests itself when the plant does not open the stomata sufficiently for vaporization in order to cool down. This results into the development of chlorosis at the rims of the leaves which develops into necrosis (death) in a later stage. In case of an excess of potassium the plant will be curbed in its development and subsequently turn dark. An excess also hampers the absorption of other cations (Ca and Mg) which is caused by antagonistic effects.
