Chamaenerion angustifolium is generally considered to be a nitrophilous plant species. Field observations suggested that reproduction from seed within rather dense populations is only occasionally achieved. It was considered that in such populations competition occurred, especially for mineral nitrogen, between the existing vegetation and the young seedlings. This assumption has been examined in a greenhouse experiment. Seed germination and seedling survival as a whole were unfavourably influenced by the presence of vegetation and addition of fertilizer nitrogen (separately or in combination), although another factor must have exercised an even greater influence.