I didn't like getting cut flowers because they always died after just 3-4 days and it seemed like a waste. So I bought a big pack of 'cut flower food' packets,

I didn't like getting cut flowers because they always died after just 3-4 days and it seemed like a waste. So I bought a big pack of 'cut flower food' packets, and now after changing out the water and adding a 9¢ packet every 5 days I can get a $6 bunch of flowers to last 2-3 weeks! Crystal is a common brand; I doubt the brand matters. My pack was so big I wouldn't use it up for years so I split it up and gave most of it away. I haven't tried but presumably you can mix up a batch of sugar and bleach powder yourself, be careful handling chemicals etc.