Opting for flowers that haven't bloomed means you'll be able to enjoy them for longer, but it can take some varieties (like the hybrid tea rose, the class most commonly found in grocery stores) up to six days to fully open, says Beth Smiley of the American Rose Society.
While putting flowers in a sunny window will speed up the process, Waga Perez says it can make the petals soft and cause them to wilt. It's best to keep the stems in warm water that contains Floralife (the powdered flower food that comes with most bouquets) and put the arrangement in a cool place away from direct rays. For bulb varieties that follow the light (like tulips), she recommends placing them directly under a chandelier or tall lamp to prevent the heads from drooping and to keep the plant growing straight up. If your flowers have woody stems (like forsythia), a vase containing equal parts seltzer and tap water will maintain the pH these varieties require, says Mead.
You know to cut about an inch off the bottom of each stem when you get a bouquet home, but to extend the shelf life of your arrangement, each day following, recut about a quarter of an inch off the stems and change (not just top off) the water.