Irrigation and horticultural practices in ornamental greenhouse production

Abstract: Irrigation in greenhouse pot plant production is traditionally managed using a tactile perceptual method. This method, in this thesis called ‘the golden grip’, is based on the grower’s experiential knowledge where water requirement is determined by combining the estimated weight of the pot (both growing medium and plant) with factors such as plant age, developmental stage and size in combination with prevailing and future climate conditions. A large proportion of this knowledge is tacit making communication about this subject difficult. Implementation of scientific results into the experientially based knowledge demands specific attention. This thesis takes a new approach to improving irrigation - a triangular approach consisting of observations, experiments and implementation that bridges the gap between science and experientially based knowledge. The importance of irrigation for plant performance is, demonstrated regarding irrigation frequency and drought levels, confirming the role played by this growth-controlling parameter. To improve irrigation management skills, the degree of reflection on reflection-in-action by commercial growers has to be increased. Suitable tools such as high precision weighing scales and dialogue-inspired methods, discussed in this thesis, have potential in achieving progress.