It is quite important to have more products at lower cost during production considering the environmental conditions. In this study, cucumber production was investigated and a fuzzy expert system was developed to determine water quantity based on the amount of fertilizer and fertility potential. As a result of the system, water quantity used during production was reduced by 7.61%. Thus, the same fertility rate was obtained by using less amount of water. In this study, low-cost product could be obtained by designing a fuzzy expert system that was not previously applied in cucumber production. © 2012 American Scientific Publishers All rights reserved.