1. Give Them a Snip
You’ve probably heard that you keep flowers fresh by cutting the stem as soon as you get them home. Here’s why it’s a good practice: Flowers have a vascular system in their stems that draws up water and nutrients to feed the blooms. If you neglect to cut them, air that has been drawn into the stems while they were out of water can block water absorption. Use very sharp scissors or pruning shears, and snip at least one-half inch off the bottom of the stems to be sure you’re cutting above possible air bubbles. Schleiter suggests doing this if your flowers are delivered in a box or tied with a rubber band.
2. Place Them in Water Quickly
To speed the process, you can cut stems under water to prevent air bubbles from forming in the stems. It’s also okay to put the flowers in a vase of water right after you make the cut. Just don’t dillydally, Schleiter says. Arrange your bouquet first, then cut the stems and put them in water.
3. Watch the Water Temp
Placing stems in hot water will cook them, Schleiter says. Room-temperature water is best, with one exception: Blooms from bulbs that flower during cooler months, like anemones, daffodils, and tulips, will do better if the water is below room temperature. “Using cool water will help them last longer,” Schleiter notes. If you have unopened flowers and want to speed blooming along, perhaps because you plan to use them as a table centerpiece in the next day or two, use warm water to help them open up more quickly. (The trade-off, of course, is that they’ll also die sooner.)
4. Remove Below-Water Foliage
Any plant leaves and flowers you leave in the vase water will rot quickly, which will spread bacteria that will kill your flowers before their time.
5.Keep 'Em Cool
Heat will hasten your flowers’ demise, so place arrangements in cool spots, away from heating ducts and vents. You can also keep flowers fresh by avoiding direct sunlight.
6. Change the Water
As we said, bacteria are the enemy, so wash out the vase and refill it at least every three days, Schleiter advises. Trim another half-inch off the stems while you’re at it.
7. Make Your Own Flower Food
Those little packets that come with many floral arrangements help to keep flowers fresh because they contain sugar to provide a little nourishment; citric acid to keep the pH low and acidic, which helps water move up the stems a bit faster and may reduce wilting; as well as antibacterial powder. If your arrangement didn’t include a packet of food or if you’ve used yours up, you can make your own each time you change the water or before you give the stems a cut. Here’s how: Mix together a few drops of bleach or a clear spirit such as vodka or gin to help fight bacterial growth, add a few drops of clear soda or superfine sugar to feed the flowers, and then crush a vitamin C tablet and add it to lower the pH.
Source: Mandy Walker