You are walking home from work when you pass the loveliest hydrangeas. At $8 for two stems at the local shop they are a steal and impossible to pass up. You bring them home, plunk them in a vase with some water, and forget about them for a couple of hours. The next thing you know, the perfect little blue petals are curling in, the whole thing is drooping, and the perky flowers you bought just hours ago are rapidly dying.