When planting cucmbers early in the unheated protected area, there is a risk of low temperature occurances, which can have a stressful effect on the plant itself. Research has shown that the use of biostimulators affects the assimilation, use and translocation of nutrients, thereby reducing the impact of stress on the plant. This paper explains how biostimulator affects the constituents of cucumber yield in the spring-summer growing season. A study was carried out to test the effects of Actiwave and Biopex biostimulators on morphological properties of fruit and cucumber yields cv. Corinto in hydroponic breeding compared to untreated control. In the period from 30 May to 26 June, there were nine harvests. In each harvest, the number and weight of marketable and non-marketable fruits were determined. In addition, the morphological characteristics (length, diameter and mass) of the marketable fruits during the fruiting were monitored. The study found that there was no statistically significant difference between the observed parameters and there was no positive effect of the biostimulators. Based on the results obtained, it is 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 with a purpose of getting more accurate results.