AbstractRunners of the cultivars Redgauntlet and Talisman produced in eastern Scotland were divided into three size grades and planted outdoors in spring or early summer after varying periods of cold storage. The percentage of plants in each size grade which flowered in the year of planting was proportional to the mean runner weight of the size grade, but initial plant size had no effect on the number of inflorescences per flowering plant. In a second trial, however, when runners (Cambridge Favourite and Redgauntlet) produced in the south of England (which were larger and therefore more complex than the Scottish runners) were grown, the number of inflorescences/plant increased with increasing runner size. Dissections of runners (Cambridge Favourite and Cambridge Vigour) from a range of sites in south-west England showed that axillary bud development, inflorescence initiation and the number of potential cropping trusses were positively correlated with crown diameter, i.e. with plant size. In Scotland mean runner size had no effect on cropping in the following year if planting took place before the end of May, but when planting was delayed until the end of June a decrease in runner size severely reduced the next year's fruit yield.