I bought five exquisite dahlias from Ayers Rainbow of Dahlias (580-5236) at the Umpqua Valley Farmers Market. Unfortunately, I broke the stem of one before I got home. Ever resourceful, I simply trimmed the stem short and floated the giant flower in a crystal bowl on my dining room table. I added fresh water every day or two and it lasted all week.
The remaining four dahlias made a stunning centerpiece on their own. I was holding the fresh flowers while I was buying peppers and beans from Jim Leet and a kind, elderly woman gave me this tip: to make the dahlias last longer, trim the stems at a sharp angle and hold the ends in scalding water for about 30 seconds. Then put them in a vase of tepid water with some 7-up soda mixed in or a penny in the bottom. Repeat the procedure every two days. She said they would stay fresh for up to ten days this way. I did as instructed (using 7-up) and mine looked good for 6 or 7 days, longer than my dahlias have ever lasted before.