Fill a clean vase with cold tap water. If available, mix in the water the preservative that florists normally include with cut flowers. Follow the instructions for the correct water-to-preservative ratio.
Prune all the leaves that will otherwise be under water.
Cut the bottom inch of each stem at a 45-degree angle.
Arrange your roses in the vase. Display them in a cool area away from direct sunlight.
Check the water every day and remove the roses from the vase whenever it becomes cloudy. Pour the water out, rinse the vase and add more fresh water to it. Prune the bottom inch of the rose stems and place the flowers back in the vase. Discard the flowers as they fade.