Hi Robyn. I order some of my dahlia tubers from Swan Island Dahlias. They have over 40 acres of dahlias & have been in business for 80 years. They're tips for cut flowers
are the following:
1) best time to cut dahlias are in the cool mornings
2) place cut stems in 2 - 3 inches of VERY HOT WATER (160-180 degrees)
3) allow to cool at least one hour
They say this sets the blooms and makes them last 4 - 6 days.