Make a natural citrus soda cut flower preservative by mixing one can of the soda with three cans of warm water in a pitcher. To prolong the life of cut flowers, the Kansas State University Horticulture department recommends using warm water, 100 degrees F. Use filtered tap water---any kind of under-sink, faucet or pitcher filter will help, or use distilled water. Use tap water if you need to, but hard or alkaline water may limit cut flower life. It is not necessary to use the exact 100 degree F temperature. Keep in mind that 100 degrees F feel only slightly warmer than the inside of your mouth, and will feel warm and not hot on the inside of your wrist.
Create a natural citrus fresh flower preservative with fresh lemons or limes. Squeeze the lemons or limes to obtain 2 tbs. of juice.
Mix the citrus juice into a quart of warm water in a pitcher. Stir in 1 tbsp. of sugar. Most homemade flower preservatives call for ½ tbsp. of plain household bleach to kill bacteria in the vase water. Flower food without bleach will extend the life of cut flowers. The sugar feeds the blooms and the citric acid helps to protect the cut flowers.
Clean a vase with hot water and dish soap, even if it looks clean. Rinse it well. Add the natural flower preservative.
Use a garden shears to cut flower stems at a 45-degree angle. This gives the flower stem the maximum surface area for taking in water and nutrition from the natural floral preservative.
Arrange the flowers in a vase filled with the homemade floral food mixture. Place them in a cool area out of direct sunlight. Change the water and add a fresh batch of natural flower preservative every other day.