When growing cucumber seedlings in heated greenhouse, growth parameters (temperature and humidity) are optimal. However, planting in unheated greenhouses may result with abiotic stress and temporary termination of growth. Aplication of biostimulants on plants increases assimilation, usage and translocation of nutrients and decrease stress effects. This experiment investigates specific biostimulants ('AminoVital' and 'Phylgreen') effects on morphological traits and yield of cucumber cultivars 'Q smart', 'Touareg' and 'Paraiso' compared to untreated control. The harvest period lasted from 21. of May to 30. July and 23 harvests were done. During harvest, number, weight and morphological traits of marketable fruits, and the share of unmarketable fruits were determined. It was determined that there was no statistically significant difference between the observed parameters and there was no positive effect on the applied biostimulants. However, cultivar 'Touareg' treated with 'AminoVital' developed the highest number of marketable fruits per plant (29) and achieved the highest yield (6737 g/plant). The highest mass of marketable fruits (250 g) was determined on the control plots without treatment at the same cultivar. At least (11.6%) of unmarketable fruits were harvested from the 'Touareg' plants treated with 'Phylgreen'. Based on the results obtained, it could be recommended to repeat the research in a greenhouse with better regulation of microclimatic conditions, with a higher number of cultivars and biostimulants, and more frequent use of biostimulants.