Summary:

The study aimed to determine the differences in lawn irriga-tion needs resulting from the topographical heterogeneity of the city of Bydgoszcz and surrounding areas. To gather the data, me-teorological measurements were carried out in the period from May to September 2012-2014, in areas diversified in terms of the degree of urbanization and land cover: the center of a large city, urban peripheries and rural area. Based on the calculated water needs of the lawn, the range of rainfall deficits during the lawn growing period was determined. It was found that seasonal rain-fall totals in the compared locations were at a similar level, but a large temporal variability of this indicator was observed in indi-vidual seasons. In terms of evapotranspiration, clear differences were noted between the analysed locations. On average, the high-est amounts of potential evapotranspiration were found in the city center, which may be the result of the urban heat island phenome-non forming over this area. However, the lowest water loss due to evapotranspiration took place in the rural area. As a result of these, the analysis showed that the lawn's irrigation needs were characterized by both temporal and spatial variability. By far the greatest irrigation needs occurred in urban space, lower in rural areas, while the lowest on the outskirts of the city, in the Fordon district.