Medium to small dahlias make the best cut flowers for arrangements. Avoid single-petaled dahlias, which tend to drop their petals. Large dahlias can be floated in a glass bowl.
Cut flowers early in the morning or in the evening.
Place stems in warm water (100°) for 1/2 hour, then place in cold water.
Display in a cool location to extend vase life (about a week).
Change vase water daily.