In this thesis, ten recycled construction materials and four natural gravels were tested and evaluated for plant compatibility from December 2006 to January 2007. This research was conducted within the framework of the EU co-financed project “Green Concrete” whose goal is to research the applicability of recycled construction materials for the use in gravel turf. Companies from Austria, Germany and Italy have taken part in the project by providing crushed brick, crushed concrete, and mixed materials from building and road construction. The growth test with cress was modified from the Austrian ordinance on compost (BGBl-Nr.292, 2001, Kompostverordnung) and formatted to assess the plant compatibility of recycled construction materials. The evaluated parameters were fresh weight plant yield, germination rate, sprout length, plant colour and root growth of the planted cress. These values were set in relation to a reference substrate, consisting of sowing substrate and powdered clay, compared and classified. The modified growth test was proven to be applicable when defining the plant compatibility with recycled construction materials. The plant compatibility of the crushed brick was classified as “satisfactory”, the mixed materials also as “satisfactory”. The crushed concrete materials did not achieve good results and were classified as “semi-satisfactory” to “unsatisfactory”. The researched natural gravels consistently had “satisfactory” plant compatibility. The recycled building materials were also tested with an addition of 25 % compost. The adding of compost had a positive effect on all researched parameters.