Data are presented showing grass productivity as grammes per 100 square centimetres under four different nutrient treatments (water, nitrogen, phosphorus and nitrogen & phosphorus combined). An experimental hillslope in the Conwy catchment was selected in August 2016. Three transects, were identified across the hillslope. Along each transect, a 1 x 1 square metre quadrat was used to delineate randomly selected sampling areas. Within each quadrat 5 individual 10 x 10 x 10 centimetre (cm) swards were collected using a spade and transported to the laboratory in Bangor University for the nutrient addition. Three different harvests at different stages (initial cut, first harvest, second harvest) were conducted in order to measure grass productivity. Harvest included removal of all vegetation within the quadrat down to approximately 1 cm in height. The data were collected to identify the nutrient limitations within the hillslope by trained members of staff from Bangor University and the Centre for Ecology & Hydrology. The data were collected for the NERC project 'The Multi-Scale Response of Water quality, Biodiversity and Carbon Sequestration to Coupled Macronutrient Cycling from Source to Sea' (NE/J011991/1). The project is also referred to as Turf2Surf. Full details about this dataset can be found at https://doi.org/10.5285/6e395915-ab5c-43f4-b4de-c9a3c5c1b956