Cut flowers in early morning or after it rains, not when they are under water stress. Cut the stem about an inch longer than you need. After cutting, immediately place cut flower in warm water. If possible, with the stem under water, cut off the bottom inch or so of the stem at an angle. This keeps air from getting into the stem. Remove all foliage that remains under water and would just rot. Recut the stem underwater every day if possible. Some people add a small amount of bleach to the water to keep down fungus and bacteria. Sugar or soda can be used for food. Others use a commercial floral preservative.