Sue, thanks for these great tips on extending the life of cut roses! I've always taken a small pitcher of water out to the garden with me when I cut blooms for vases but for many years I didn't know about cutting stems at an angle, and it does indeed seem to help with allowing better water uptake, helping the blooms stay fresh and last longer. I never seem to have floral preservative on hand and a couple of times I used a pinch or two of sugar in the water but the majority of the time I use lemon-lime soda (Sprite) because we buy it by the case for my husband.
When I was purchasing a bouquet at a florist many years ago, I asked for tips on how I could keep the flowers fresh, longer. She told me that when I got home I should immediately put the cut flowers in ICE WATER and place the vase in the refrigerator for a couple of hours!! I was young then and figured she was the expert and knew what she was talking about but once I brought the vase out to normal room temperatures, the flowers seemed to wilt within 24 hours! I learned from that experience that lukewarm water doesn't shock the flowers like ice water does.