One of the most important cut flowers, is Gerbera ( Gerbera jamesonii ) and belong to Asteracea family. quality of cut flowers is one of the valuable factors. So color and number of flowers, stem flower thickness and length, head diameter and vase life of gerbera, much attention has been paid. In this research, the effect of seaweed extract was evaluated in order to investigate the qualitative and quantitative characteristics and vase life of gerbera" Rosalin" during both pre and post harvest experiments. The experiments included 5 concentrations of seaweed extract in two harvesting times in a split plot in time, in the first experiment (before harvest), the experimental design was based on a completely randomized block design. The second experiment (post harvest) was based on a completely randomized design and executed in four replications. Seaweed extract was applied spray every two weeks and in 5 stages, and the harvesting time was considered 2 weeks after the fourth and fifth spray application.The results showed that the 0.2% concentrations of seaweed extract derived from Ascophyallum nodosum increased number of flowers, length of scape, anthocyanins content before picking up, calcium levels and the vase life cut flowers, 65.5%, 12.7%, 17.6%, 79.7% and 45.8% respectively compared to the control. Also, The Concentration of 0.15% improved calcium content and fresh weight of flower, chlorophyll b, total chlorophyll and relative water content, 25.6%, 8.3%, 19%, 10.8% and 10.6% respectively compared to control. After 9 days, the highest weight loss was observed in the control.The mean Comparison of results between harvesting times showed that the highest number of flower, flower fresh weight, chlorophyll content, anthocyanin, calcium and the most extended Gerbera vase life was observed at the time of the second harvest which have been after the fifth spraying Gerbera. The most percentage of weight loss after 9 days and the highest EC was at the time of the first harvest or after the fourth spray. In general, for increasing the vase life and number of gerbera flower, it is recommended to use five-time spraying of seaweed extract at a concentration of 0.2%. Keywords : Gerbera jamesonii , Seaweed Extract , Vase Life, Anthocyanin