This study was conducted to investigate growth and flowering of hydroponically-grown carnation as affected by substrate and planting date, Three substrates, coir, perlite, and coir＋perlite(1：1. v/v), and two planting dates. May 1 and September 1 were used. Plant height and stem diameter at harvesting time of cut flowers were greater for the September 1 planting than for the May 1 planting. The plants planted on May 1 produced flowers with weak stems and short stem lengths. In addition, flower weight and blossom width were gloater for the September 1 planting than for the Mar 1 planting. The planting date had no significant effect on the number of petals, The carnation planted on May 1 flowered 50 days earlier compared to those Planted on September 1. Plant height and number of petals were the greatest in the plot of coir substrate. The results indicated that for commercial production of cut carnations in a hydroponic system, planting on September 1 is better than May 1. In addition. the results confirm that coir is the superior substrate for the production of cut carnations in a hydroponic system compared to either Perlite or coir＋perlite mixture.