This study assessed the effectiveness of suburban planning in the field of sustainable land-use management. Poznań County was selected as the research area. The scope of the research concerns the changes in land-use purpose and their impact on the landscape and ecological values. The methods used included quantitative research, analysis, and a case study. The conclusions indicated systemic errors in the development of suburban areas, including discrepancies between the development strategies of larger areas (e.g., metropolitan areas) and local studies of spatial development directions. The proposed solutions included the legal empowerment of larger development strategies and promoting the valuation of ecosystem services as a balance for economic analyses.