Here's some helpful information when you receive a bouquet of cut flowers:
If the flowers are packaged in blocks of floral foam or water tubes, pull the stems out of the packaging. Remove any foliage that will be below the water line. Mix the package of fresh flower food in cool water as directed. Then cut about half an inch (one centimeter) off the bottom of each stem, preferably under water. Place the stems immediately in the solution.
Keep your flowers out of direct sunlight and sources of heat or draft (TV, appliances, radiators). If you can, put them in a refrigerator or cool room overnight. Check the vase daily and add flower food solution as needed to keep it full.