Flowering plants have an increasing need for phosphorus and potassium. With HESI PK 13/14 we fully meet this need. The flowering phase is the culmination of a plant's life. The metabolism then works to maximum and large amounts of enzymes are provided for flowering. The specific substances that are particularly needed now are phosphorus (for the enzymes and the genetic material) and potassium (for transport within the plant). To be sure that the plant will not, unnecessarily, be over-stressed too early, HESI PK 13/14 will not be used until the second half of the flowering phase until one week before the end of the cycle.