Manutec Hydrangea Blueing Fertiliser is a specific fertiliser developed to maintain safe nutrient level and optimum pH values that are suitable for producing blue hydrangeas.
As soil pH determines sepal colour in hydrangeas, it is most important that pH of the soil or potting media is determined and adjusted prior to growing period. Any pH between 5.5 and 6.0 is acceptable during plant growth, but when forcing begins the pH for a crop of blue sepals must be 5.5 or lower. pH can be lowered by adding sulphur to the media and maintained by the regular use of this solution.