The potential role of soil pH in modulating plant productivity was assessed on the basis of dry mass, harvested in the form of 0.25 m 2 quadrats, in two low-productivity upland grasslands of northern Greece subjected to annual factorial nitrogen (N) and phosphorus (P) fertilization (15 g N m −2 year −1 and 10 g P m −2 year −1) over a minimum period of 3 years. It was hypothesized that under these particular conditions, a positive relationship would exist between soil pH and plant productivity and, further, that N or P fertilizer application of a nutrient limited system, would result in a weakening of this positive relationship. A significant positive relationship was confirmed between soil pH and plant productivity in one of the two study areas and a positive trend in the other. Moreover, plant productivity increase, following fertilization, appeared to have a detrimental effect on the soil pH-plant productivity relationship. Findings support the original hypotheses and strengthen the idea that plant diversity-mediated soil pH-plant productivity relationships are a result of the more intense plant speciation that occurred under the more “typical” soil conditions of higher pH in temperate as opposed to tropical regions.