To evaluate the possibility of replacing natural compounds for chemical ones as antimicrobial agents in preservative solutions of cut flowers, a factorial CRD based experiment of three replications was conducted at the Department of Horticulture, Faculty of Agriculture, Tehran University. Three concentration levels of 50, 100 and 300 mgL-1 from Eugenia caryophyllata were prepared. Cut gerbera "Ecco" flowers were continuously treated with each concentration of the compound. Results indicated that longevity, fresh weight, vase solution uptake, number of bacteria in preservative solution and color change of stems were affected by essential oils and extracts. Mean longevity of treated flowers with distilled water was 3.5 days, while mean longevity of treated flowers with Eugenia caryophyllata essential oil at 300 mgL-1 was 8.4 days and mean longevity of treated flowers with Eugenia caryophyllata extract at
100 mgL-1 8.3 days. Also it was observed that all the treatments endured more longevity than control flowers. Maximum values of fresh weight were observed in Eugenia caryophyllata essential oil at 300 mgL-1 followed by Eugenia caryophyllata extract of 100 mgL-1 concentration.