How To Look After Hydrangeas In A Vase. This will kill any bacteria in the vase before the flowers are put in it. Cut hydrangeas in the morning and choose only the most mature blooms.
Snip the ends of the hydrangeas again the same as in Step 2. You can use the boiling water trick again after you cut them to increase vase life or add in a little flower food or simple cane sugar from your pantry in the vase Make sure to keep your arrangement out of direct sunlight. Since the flowers are fresher they will last longer in your arrangement.
This will kill any bacteria in the vase before the flowers are put in it.
I have tried this trick and it works. Hydrangea creates a sap that can seep out after you cut it. According to Hale hydrangeas take in water through the flower petals as well as through the stems. Pour boiling water into a cup and place the stems into the cup.