Follow these simple guidelines to ensure the longest possible vase life for your flowers:
Whichever vessel you choose, it should be as clean as possible. In other words, your vase, glass or cup should be clean enough to drink from!
Ensure that no leaves are below the water line.
Change the water on a daily basis.
Use flower food when you first put the flowers in a vase and again four or five days later.
Trim the flower stems as needed.
Finally, keep your flowers away from fruit. Ethylene gas produced by bananas, melons, apples and other fruit can cause flowers to expire prematurely.