What works better than sugar, too, is cornstarch check your flowers everyday and shake it so the cornstarch rises from the bottom to at least the middle (if your flowers are a little short).
The reason sugar works is not to nurish the flowers s but that it’s ntibacterial! Sugar and Honey are natural anti bacterials and used to be used as pastes to speed healing of elderly patients bedsores.
This website gave me some good imformation for my science fair project. I’m doing it on what kills flowers quickest when submerged in 3 drinks: diet coke, coke, and water. Finding out that sugar keeps them living longer, that totally changes my theory. :) :0) :O
I read that using a vase that was short and squat to hold a fair amount of water helps. Since water high up on the stem deteriorates the stem. I have a weird little vase like affair that has a cluster of pins in the bottom that the stem sticks on and it seems to keep the flowers fresh longer, but maybe it is the low level of water in the short squat container. It looks like a flying saucer with a hole in it where the stems go. Just a though.