The effects of winter green manure crops on organic cucumber production were determined in unheated greenhouse conditions in order to integrate soil building and conservation practices, which are critically important in greenhouse production without crop rotation. The study was conducted between 2006 and 2008 to compare (1) pea (Pisum sativum L.), (2) Italian rye-grass (Lolium multiflorum L.), and (3) common vetch (Vicia sativa L.) as winter green manure plants. These treatments were compared with a control without green manuring (4). All of the plots were divided into halves, and poultry manure was applied as 0 (-PM) and 0.75 kg m(-2) (+PM) to each. Cucumber (Cucumis sativus 'Sardes') was grown as a spring cycle production after winter green manure plants were incorporated into the soil. Treatments were evaluated in terms of yield, fruit quality parameters such as electrical conductivity, pH, titratable acidity, total soluble solids, and dry weight. Soil fertility and pest/disease incidence were also determined. It was found that cucumber yield varied between 9.7 and 16.3 kg m(-2) and between 10.0 and 13.6 kg m(-2) in the first and second spring growing seasons, respectively. Green manuring improved the organic matter and nitrogen contents of the soils. Other available nutrients in the soil were also analyzed and found to be sufficient. Additionally, the nutrient status of the cucumber plants was found to be sufficient. Pea and vetch proved to be efficient as winter green manure crops for vegetable production in greenhouses. Poultry manure also produced positive effects, in particular on soil total N content. Therefore, it could be used with green manure crops according to the N content of the soil.