Her face lit up at the sight of the beautiful roses you gave her for Valentine's Day. But how's she going to make them last?

University of Georgia extension horticulturist Paul Thomas said it's not hard to keep your roses looking great.

"Clean water and vases are important to prolonging the life of cut flowers," he said. "Wash vases often, because microorganisms remaining in unclean vases multiply quickly."

Thomas said changing cut-flower solutions once a day and cutting one-fourth of an inch off the stems in a bowl of water prevents molds and fungi from clogging up the stem.

"It's important to use sharp scissors," he said. "Blunt ones will clog up the stem even more."

Treating the water in the vase can prolong your arrangement's freshness. "Add four or five tablespoons of sugar per gallon of water, or add floral preservatives available from your florist," he said. "Use preservatives according to the instructions. Too high a concentration may be harmful to the flowers."

Preventing the flowers from drying out is important, too.

"Flowers retain a fresh appearance much longer when the air humidity is relatively high," he said. "If they're kept in a room with dry air, they should be misted with water once a day or every other day. Putting the arrangement in the refrigerator at night will prolong its life, too, if the fridge contains 10 percent to 15 percent humidity."

Thomas said keeping the flowers out of direct sunlight or drafts of warm or cold air keeps them from being dried out.

UGA extension horticulturist Gary Wade said sagging roses can be perked up.

"When cut roses begin to droop or wilt, submerge the entire flower into a flat pan of warm water," he said. "Gently straighten the heads and cut off the stems, while under water, two inches from the ends. Allow the roses to stay two hours in the water to revive."

Once a flower dies, however, it's best to remove it from the bunch.

"Dead flowers produce ethylene that kills other flowers rapidly," Thomas said. "Also, remove unnecessary foliage below the water level, because it decays easily."

Wade said some of the quality and freshness of roses may be lost in their transportation.

"Roses sold in Georgia are imported from South America," he said. "The Georgia climate is too hot, and the heat makes for a high incidence of disease."