1, The growth of Sphagnum fallax was studied in a glasshouse experiment. Capitulum diaspores of S. fallax were cultivated on five different types of bare peat core, representing a gradient of increasing disturbance. Increases in length and weight were measured. Three microclimates were simulated by protecting the bare peat with a shading mesh and a plastic cover in combination with two water levels. 2, Significant differences in the growth of S. fallax were observed in relation to microclimate changes. Protection techniques such as shading mesh and perforated plastic film allowed a better development of the diaspores compared to bare peat. A plastic cover caused the best growth and compensated for a low water table level. 3. Feat properties are critical when diaspores grow in direct contact with decomposed peat. The porosity, and especially its vertical pattern in the peat profile, proved to be an important factor. A particular combination of microclimate conditions at the surface of the bare pest, and physical properties of the upper. peat layers, may favour the growth of S. fallax diaspores even where there is a low water table. 4. Restoration of Sphagnum species on cut-over bogs needs to consider both the microclimate conditions at the surface of the bare peat and the peat properties themselves. These factors are important for the diaspores, particularly in periods of climatic and hydrological stress. In such situations, commensalism with some vascular plants may be a useful trigger for Sphagnum growth.