The makers of organic food can’t put artificial colors in their products. But they can use colors from natural sources such as beets, seeds and flowers.

The result can mean beets in ice cream, carrots in candy and vegetables in fruit smoothies — which may not sound appetizing but is supposed to make organic food more desirable.

To compete with mainstream rivals, the rapidly growing organic foods industry wants its pastas, cookies, cereals and other foods to appeal to the eye as much as the conscience of the average consumer.

“Food is a sensory experience,” said Kelly Shea, vice president of organic stewardship for WhiteWave Foods, a subsidiary of Dean Foods Co., one of the largest producers of organic products. “When we eat, we’re feeding our taste buds and our eyes and our nose.”

Organic colors come in a relatively limited palette. Yet the organic trend is to encourage the creativity to devise natural coloring agents.

Certain strains of beets and carrots — along with other produce, seeds and flowers — are harvested purely for their hue. And demand is growing, with companies persuading farmers to grow more crops for color.

The colors can be more than just a pretty sight. They’re also believed to be good for you, said Carlton Colmenares, research farm manager for Hibiscus Hill Plantation, a 277-acre organic research and production facility for hibiscus flowers in Texas.

Brightly colored crops are packed with disease-fighting antioxidants that are found in pigment, he said.

Hibiscus Hill Plantation sells a specially bred organic North American hibiscus for its antioxidant power, he said, and processors could easily use them to add a bright reddish tint to certain products.

But some people in the natural foods industry don’t see much demand for organic food coloring beyond a small market for children’s food, a fast-growing organic category that needs colors to tempt picky eaters.

“Food coloring doesn’t really jibe with the organic industry,” said Scott Simons, spokesman for Whole Foods Market , the nation’s largest organic retailer. “Our customers are looking for foods in their most natural, unadulterated state.”

The U.S. Department of Agriculture allows producers to use natural food colors even if they aren’t certified organic, although some purists argue that processors should do without until there’s an organic alternative.

Products that use natural colors can bear the USDA Organic label. But they would have to use all organic ingredients, including organic colors, to label their products “100 percent organic.”

That’s an attractive advantage, which is one reason why WhiteWave’s Horizon Organic dairy brand would like to find organic colors as soon as possible, Shea said.

WhiteWave, which lists natural colorings in some Horizon yogurts, smoothies and cheeses, uses two of the most popular natural colors: annatto, a reddish pulp from a tropical tree, and natural turmeric, a yellow spice often used for curry. The company is also testing an organic color, but officials wouldn’t say what kind.

WhiteWave experimented with coloring strawberry milk, but none of the current colors worked, Shea said.

So Horizon strawberry milk is white, unlike the bright pink nonorganic brands on the shelf. Shea said WhiteWave might reconsider adding reddish tint once there’s a suitable — and preferably organic — option.

“This is going to be a market-driven opportunity for suppliers,” she said. “If there’s enough of a demand, they’ll create the supply.”

Interest in natural food coloring picked up in the 1970s, when the Food and Drug Administration pulled the popular Red Dye No. 2 synthetic food coloring because of fears that the coal tar substance could cause cancer.

Artificial or synthetic colors are often made from petroleum-based substances and have been associated with health conditions such as attention deficit disorder in children. The FDA says its approved color additives are safe.

Food coloring manufacturers say they’ve already seen increased orders for natural colors and interest in organic alternatives, although the industry’s growth is hard to measure because many producers don’t specifically market their products as color additives.

Overall, organic products were projected to grow 14 percent from last year to almost $16 billion in retail sales in 2006.

This spring, the National Organic Standards Board is scheduled to devise a precise list of natural colors that can be used in organic foods until organic colors are commercially available.

Makers of organic caramel color say they can meet demand right now. D.D. Williamson, a color manufacturer in Louisville, Ky., offers an organic caramel color made from cane syrup and rice syrup.

Colas, breads, cookies, soy sauce, cereal and even pet foods use caramel coloring. It’s in “almost anything that’s brown,” said Owen Parker, vice president of research and development. Parker said the color is made by heat-treating the syrup.The difficulty in getting natural food colors varies by crop.

Beet farmers in Wisconsin are growing a variety of table beets chock full of deep red pigment for natural food coloring. Converting some to organic would be easy, said Irwin Goldman, professor of horticulture at the University of Wisconsin-Madison.

The beet color works well in yogurt, ice cream and candy, he said, but doesn’t hold up in baked goods.

Stabilizing color is a challenge with many natural sources, said Stefan Hake, chief executive of GNT USA, a Tarrytown, N.Y., company that produces natural food colorings.

Prime pigments can come from elderberries, cherries, strawberries, pineapple, pumpkin, red cabbage, orange carrots and even purple carrots, but understanding their chemistry is key.

Put blueberry juice into a glass of Sprite or 7Up, and it turns red, he said. Put blueberry juice in milk, and the color shifts toward the bluish side, and it’s gray by the end of the day.

“It’s not just how color works,” he said. “It’s how does it interact with what you’re adding it to.”