"There's very little waste, and we're able to give them just what they need at every different stage of growth," she said.

Tomatoes with names like Kellog's Breakfast, Hawaiian Currant and Brandywine bloom in colors ranging from marigold to purple. They're also experimenting with purple carrots and striped radishes. Romo said most vegetable growers breed for such desirable characteristics as sugar content and resistance to pests, but their latest project is to try to breed for vegetables with higher nutrition content for humans.

Over in the lettuce houses, supervisor Susie White showed off rows of baby lettuces floating on rafts with their roots in water ponds, plus a watercress that, instead of being long and leggy, is a tangle of sweet, peppery leaves. She's even invented a trio: three types of lettuce planted together, so that they grow into a multicolored bouquet. The challenge is balancing the variables: light, water, water temperature, air temperature, nutrients and oxygen content of the water.

Actually, he figured it out by accident. Frustrated with his lack of success at growing the mushrooms indoors — as he does with oyster, shiitake and other types — he stacked the racks of unsuccessful starts outside the back door of his Hamakua facility. Heavy rains fell, and the next thing he knew, the fungus was growing like crazy. Now the crinkled ears sprout from plastic jars of sawdust in a shade net tent. Not yet on the market, the mushrooms are being tested with chefs, including Alan Wong. Stang says they work well in stir-fries and sautes. He likes to shred them into poke, too.

"Green tea is something Americans want for the antioxidant health benefits, but they don't like the taste, the astringency and bitterness," he said. The Mealani team is working with four varieties and, on the day when Alan Wong's group visited, served two very different brews. One was mild and sweet with just a hint of bitterness in the finish. The other was like drinking pikake, very floral and perfumed.

Making tea is a painstaking process: Just the top two leaves and the bud are used, and they have to be hand-picked. There follows a series of steps — aging, drying, roasting, tumbling and pressing.

"It's amazing, at the different steps, how things can change," said Yamasaki. "We're still learning."

A number of farmers have already started cultivating tea around Volcano and Waimea (tea likes the misty conditions in both places).

HAMAKUA MUSHROOM POKE

Mushroom grower Bob Stanga invented this vegetarian poke, made with his Hamakua Exotics meaty and slightly crunchy oyster mushrooms.

Reach Wanda A. Adams at wadams@honoluluadvertiser.com.