Extend the life of your flowers...

For floral arrangements

Keep the vase filled (or floral foam soaked) with water containing a flower food provided by your florist. Flower foods make flowers last longer but it is important to follow the mixing directions on the flower food packet. Most packets are to be mixed with either 2 cups or half a cup of water. Flower foods should not be diluted with more water than is specified on the packet.
If the flower food solution becomes cloudy, replace it entirely with properly mixed flower food solution. If possible, re-cut stems by removing one to two inches with a sharp knife. Be sure to use a sharp knife or clippers that will not crush the stems. Immediately place the stems into solution.
Keep flowers in a cool spot, away from direct sunlight, heating or cooling vents, directly under ceiling fans, or on top of televisions or radiators. (Appliances like televisions give off heat, which causes flowers to dehydrate.) Most flowers will last longer under cool conditions.

Keep your flowers in a cool place until you can get them in a flower food solution. Don't forget how important it is to follow the mixing directions on the flower food packet.
Fill a clean (washed with a detergent or antibacterial cleaning solution), deep vase with water and add a flower food from your florist.

Remove leaves that will be below the waterline. Leaves in water will promote bacterial microbial growth that may limit water uptake by the flower.
Re-cut stems by removing one to two inches with a sharp knife. Place the flowers in the vase solution you've prepared.