The American Chemical Society's Reactions series is here to help. Here's everything you need to know to science your flowers into submission.
1. Cut those stems
Flowers use transport systems called xylem to bring water up through their bodies using capillary action. There's a lot going on in there, but you can basically think of the system as a straw. But plants don't suck — they rely on the surface tension of the water to make it climb up the narrow passage as molecules stick to the sides.
Because plants use a passive method of water collection — and rely on water to stay perky and fresh-faced — you want to make the journey as short and easy as possible. Flowers will have an easier time getting water to their petals and leaves if their stems are on the shorter side. Plus, trimming the stems of your flowers right before you plunk them in a vase will ensure a fresh, healthy opening for that water to travel through. If you cut the stem at a slight angle while holding it under water, you can minimize air bubbles in the xylem, which make it harder for water to make its way up. Be sure not to crush the stem, and plunge the bouquet into water immediately after trimming.
And make sure to remove any leaves that slip below the water line. These can decay and rot, encouraging bacterial growth.
2. Make the water as floral-friendly as possible
Just turning on the tap and filling a vase isn't good enough. Instead, clean out your vase with soap and water. If you can minimize the number of microorganisms living alongside your flowers, you can help keep them healthy for longer.
Then, fill the vase with warm, filtered water and let it sit for a few minutes. This will let the water de-gas a little, limiting the air bubbles that can gurgle into your flowers' plumbing.
Finally, add plant food. This stuff contains sugar (the actual food part), some citric acid (to make the water more acidic, which plants are into) and some kind of bleach or other antimicrobial (to keep the water clean).
Don't bother putting a penny in there — that's just an old wives' tale. But you can actually make your own plant food very easily. Just remember to use a complete recipe — one with all three of these components — instead of just dumping sugar in, since that's likely to attract bacteria.
The best way to give your flowers a long life is to change the water every single day, which kind of sounds like more trouble than most flowers are worth.
3. Be smart about storage
Leave your flowers in a cool place, because this will slow down their metabolic processes and keep them going a bit longer. If you're going out of town for a while and won't be home to gaze upon them in all their splendor, stick them in the fridge until you get back.
But not next to fruit! You know how fruits give off gases that cause other fruits and veggies to ripen? Those same gases (ethylene) will make your flowers "ripen," too — and that means a quicker death.
There you have it, folks. Whether you're buying mom a special bouquet, fielding endless bunches of flowers from your flock of romantic admirers, or just picking wildflowers for your own amusement, now you know how to keep them from dying — at least for a week or so.