Introduction: Mini-forests are structurally and species-rich plantations of densely planted trees and shrubs in small areas, usually less than 1000 m2. There is an increasing demand for miniforests as an innovative solution for promoting biodiversity, improving the urban climate and creating green oases in densely populated areas. Nevertheless, there is a lack of documented evidence on the effects of mini-forests. We address this issue and set out guidelines for recording the ecosystem services of urban mini-forests.Methods: Attractive design with 30 different species in 1)mixed planting and 2) planting in groups of tall trees, smaller trees and shrubs. Additionally, various provenances are being tested for climate fitness.Activities: Regular plant growth and vitality monitoring and assessment of biodiversity. Air temperature and humidity at 50 cm height. Soil temperature and moisture at 10 cm depth. Root collar diameter and height measurement to calculate the above-ground biomass. Soil samples for soil carbon, bulk density, chemical and physical parameters. Surveys assessing public views.Objectives: For the first time, scientifically validated data from Austria, regarding the climatic suitability of the plantings, the impact on microclimate and particulate pollution, above and below ground carbon sequestration, plant and animal biodiversity, and social issues such as community acceptance and use of the miniforests as green recreational and educational spaces.Overcoming hurdles in practical implementation, like:- How dense? 1 or 2 plants per m2?- Mixed planting, random or in small groups?- Climate suitability of native vs. non-native woody species?- How much and which care is required, and for how long?