Provenances originating from French and German sessile oak seed sources were analysed 23 years after planting at nine different locations in Northwest Germany. In general, German provenances are better adapted to the prevailing conditions of the test sites showing a better survival. Differences between the provenances in measured growth characters (“DBH”, “height”) were less pronounced than in observed quality parameters (“form”, “crown”). Five of the German provenances showed a better stem form; only three French provenances exceeded the overall mean. Variation in phenotypic stability between provenances could be observed as well as rank changes of provenances measured at different ages. Observed variation in stability was mainly attributable to single provenances, however, no pattern of variation could be detected. Besides the German seed sources “Bundesgebiet”, “Spessart” and “Göhrde” some French provenances (“Reno Valdieu”, “Bertranges”, “Darney” and “Der”) can be recommended as substitute in low crop years.