Strip the roses of their leaves. Clip the thorns off the stems with floral scissors. This will allow the stems to rest against each other in the vase so the blooms can be closer together.
Cut the ends of the rose stems to the appropriate length for the vase. Do not cut all the rose stems to the same length. Add or subtract an inch or two to different stems for variation.
Arrange the roses in the vase. Place the taller roses in the vase first, then add the shorter roses. Move them around until you achieve the look you want.
Lift the bouquet from the vase, holding the arrangement in place with your hand. Wrap floral tape around the roses about halfway up the stems. Add another length of floral tape around the roses about two-thirds of the way up the stems. This will keep the roses together.
Place the bouquet back into the vase. If you need to make any adjustments, remove the floral tape to rearrange the blooms. Fill the vase with water to complete your arrangement.