For longer lasting and better looking floral arrangements
Place your flowers in a cool place
Cut flowers like to be kept in a cool place between 18 to 22" Celsius or 65 to 72 degrees Fahrenheit.
Keep the water clean and topped up
If the water that your flowers are in or the flower food solution becomes cloudy replace it with fresh fluid, at the same time re cut the flower stems by removing the bottom one to two inches of the stem.
Try to keep your flower container topped up and use floral foam soaked with water containing a flower food.
Try to avoid placing your flowers on top of electrical appliances and other direct heat sources such as direct sunlight and heating, you should also note that overly cold breezes will also adversely effect the life of your cut flowers.
For loose bunches of flowers
If you can't get your flowers into a flower food solution right away, keep them in a cool place.
Fill a clean, deep vase with water and add flower food.
Remove leaves that will be below the waterline. Leaves in water will promote bacterial growth and turn you flower solution prematurely cloudy.
Re cut the stems underwater this will allow the stems to draw in water instead of air, then place your flowers in the vase solution that you've prepared.
If you purchase loose flowers for your own arrangements you should also consider these tips:
When selecting flowers
Look for flowers with upright, firm petals and buds beginning to open. Yellowish spotted and drooping leaves are signs of age. When using woody stems and branches, cut the flower stems with pruning shears, then place them in warm water containing fresh flower food to promote flower opening.