The demand for roses, the traditional flower for Valentine's Day, reaches its peak this week -- and so does the price, which is $45 to $75 for a dozen long-stemmed roses from Washington area florists. That is $10 to $30 over the January price.

Flower sellers say that the annual increase in the Valentine's Day rose prices here and elsewhere in the nation is the result of supply and demand factors.

"A month ago, in the middle of January, there was no demand for roses," said Steve Snyder, manager of Pennock, a Washington wholesale flower company. "So the market demand and price really dropped." But prices go up, he said, as the flower industry begins responding to the demand of Valentine's Day, and the supply tightens. He said that the nature of the rosebush adds to the pressure for price increases at Valentine's Day.

"The rose is a flower you have to keep growing all year; you can't increase production for Valentine's Day -- at least not significantly," he said.

"So the price drops in January, after Christmas, when there is no demand for roses, and in July and August, when people have roses in their back yard.

"It goes up in February for Valentine's, when roses get scarce due to demand. Then, after Valentine's, when demand drops and roses start coming back, the price drops."

Retail florists offered a similar explanation for the annual rose price fluctuations.

"It is supply and demand, absolutely," said Tom Powell, owner of the Flower Gallery, 1700 L St NW. He said his best long-stemmed roses are $65 a dozen, up from $41 last month.

Blackistone, one of Washington's oldest florists, has roses for $60 a dozen boxed and $65 a dozen arranged, compared to $45 a dozen in mid-January, said Marilyn Evanick, manager of the H Street Blackistone. The increase was necessary, she said, due to increases in grower prices. "We probably could mark up our roses even more, but we don't believe in gouging our customers," she said. "We like to keep them coming back."

Washington area prices for roses generally are higher than in other parts of the country, according to Drew Gruenburg, spokesman for the Society of American Florists. He said that a recent survey found that a dozen roses were selling for $33 in Pennsylvania, $35 in Texas, $43 in California and $60 in North Carolina. That compared to about $40 to $70 for a dozen roses in the D.C. area, he said.

"Prices are a little higher here in Washington," he said, "because of the demand and the life style and the economic standards. People in Washington are more willing and have the funds available to pay a little more."

In an informal check of area florist shops, the lowest price found for roses was at Behnke's Flower Shop in Beltsville, where a dozen roses were $45, up $10 from a month ago. The highest price found was at Clark's Flowers in Silver Spring, where roses were $70 a dozen boxed and $75 a dozen arranged, up from the January price of $30 to $45 a dozen.

Susan Mauck, one of the partners in Clark's Flowers, said the increase reflected the higher wholesale cost of roses.

In recent years, as rose prices soared, Mauck's store has shifted its emphasis away from roses and toward fresh flowers in reds and whites, she said. As a result, she said, only about 20 percent of her store's sales now are for roses.

But the trend nationally is toward increased rose sales, particularly at Valentine's, according to Jim Krone, executive vice president of Rose Growers Inc., a Michigan-based rose producers' association.

He estimated that about 60 million roses will be sold this Valentine's, up from 58 to 59 million last year.

He said that the Valentine's Day sales of roses generally account for about 10 percent of the annual rose sales.