Large head Light Blue Hydrangeas.
 
Please note: 

All cut flowers do better in clean water, so it's important to change the water every two to three days, particularly if it starts to look cloudy. Cloudy water indicates the presence of bacteria, which will prohibit the hydrangeas from taking in water.
 
Follow the same instructions you used when originally preparing your hydrangea cut flowers.Empty the vase, clean it out and refill with warm water enhanced with sugar, floral preservative and bleach as previously noted. Smash the stems open, place in warm water and then put the hydrangea in the vase.
 
Hydrangeas love hydration.