Flower food comes in small packets and is used to keep cut flowers fresh as long as possible. Flower food does two things. It keeps bacteria from growing in the water that the flower is set in, and it feeds the flower so that the flower can stay alive as long as possible. Flower food can be substituted as long as the ingredients used have the power to kill bacteria and feed the flower.
Fill a vase three-quarters of the way full with water. Let it reach room temperature.
Add 2 tbsp. apple cider vinegar to the water. This inhibits bacteria from growing in the water and killing the flower too early.
Mix in 2 tbsp. of sugar to the water in the vase. This will replace the part of the plant food that feeds the flowers.
Cut your flower stems at an angle so they they don't get any air bubbles. Then immediately place the flowers in the vase of prepared water.