Abstract: Improvements in cropping technology and the development of novel crop varieties allow growers to cultivate horticultural crops throughout a larger proportion of the calendar year. Some crops are now approaching all year round cropping where this was never possible before. Crops grown throughout the winter in passive greenhouses represent a particular challenge for the implementation of biological control. In this study we focused on improving biological control programmes in the southern Spanish region of Almeria. Using greenhouse climate data we were able to construct a model temperature profile representative of an ‘average day’ for various periods of the winter. In these conditions we analysed possible barriers to the successful implementation of predatory mites as biological control agents for Western Flower Thrips (Frankliniella occidentalis) and Whitefly (Trialeurodes vaporariorum and Bemisia tabaci). We show that the formulation of products is a key aspect in improving the control of these pests. IPM programme design and implementation strategies are discussed in-light of these findings and the wider relevance of the study is identified.