Water usage is a vital issue for all agricultural crops as well as for ornamental crops. To obtain high quality flowers, it is essential to supply water when it is required. A problem which is common with cut flower growers are determining when to irrigate and the amount of water to apply. The effect of two irrigation intervals (I(1): 10 mm pan evaporation and I(2): 20 mm pan evaporation) and four pan coefficients (Pc(1) = 0.60 Epan, Pc(2) = 0.90 Epan, Pc(3) = 1.20 Epan and Pc(4) = 1.50 Epan) based on the amount of evaporation measured by a Class A Pan (CAP) on flower yield and flower quality of carnation (Dianthus caryophyllus L. cv. "Judith") plant grown in a plastic greenhouse and irrigated by a drip irrigation system under Mediterranean conditions was investigated. Irrigation intervals varied from 1 to 6 days in I(1) and 4 to12 days in I(2) treatments. Both irrigation intervals (I) and pan coefficient (Pc) significantly influenced carnation yield. Maximum yields were obtained from the I(1)Pc(3) treatment as 6.7 and 6.8 flowers per plant and minimum yields from the I(2)Pc(1) treatment as 5.6 flowers per plant in the first and second year of the experiment, respectively. Similarly, irrigation intervals and pan coefficient had significant different effects on quality parameters such as flower stem length, flower stem diameter, stem weight, flower diameter, and vase life. Better flower quality was obtained from the treatments of higher frequency irrigations with high pan coefficients compared to lower frequency irrigations with lower pan coefficients. In conclusion, I(1)Pc(3) irrigation regime is recommended for growing cut flower carnation in order to obtain higher yield with improved quality.