Fill a large buck with warm water. Add a floral preservative at the rate specified on the package. Mix the preservative into the water with a spoon until it dissolves completely.
Fill a sink with warm water. Remove the leaves on the portion of each rose's stem that will be underwater. Hold each rose stem under water in the sink. Use a knife to cut off the bottom 1-inch of stem. Make the cut at a 45 degree angle to expose more fresh stem tissue. Move each rose immediately from the sink to the bucket of water.
Place the bucket of roses in a dark, cool room. Leave the roses to soak for one hour to allow them to re-hydrate.
Move the bucket of roses into a refrigerator if you do not need them immediately. Leave the roses in the refrigerator until needed.
Clean a vase with warm soapy water. Rinse the vase and fill it 2/3 full of lukewarm water. Mix in a floral preservative at the rate recommended on the package. Remove the roses from the refrigerator.
Cut off the bottom 1-inch of stem on each rose while it is still in the bucket of water. Move the roses from the bucket to the vase. Arrange the stems as desired.
Keep your vase of roses in a cool room out of direct sunlight during the day. Place the vase of roses back into the refrigerator each night. Change the water in the vase every other day. Re-cut the stems every two to three days.