University of Hawaii researchers are poised to start their first harvest of industrial hemp in Waimanalo, while crop advocates explore opportunities to tap into the multimillion-dollar demand for the plant’s products in the United States.

Advocates estimate some $600 million in hemp is imported into the U.S. annually.

“Our small little plot is the beginning of what I believe will be a major agricultural crop for Hawaii,” said state Rep. Cynthia Thielen (R, Kailua-Kaneohe). “These plants are amazing.”

Researchers are expected to initiate the plot’s first harvest on Thursday.

Thielen, a leader in promoting hemp farming as an agricultural mainstay, said industrial hemp has thousands of uses, ranging from health products to fuel sources.

One of the major firms looking at hemp as a potential commodity is Hawaiian Commercial & Sugar Co., with 36,000 acres under cultivation on Maui. Biologist Harry Ako, the chief scientist involved in the cultivation at Waimanalo, said the sugar company is looking at growing hemp for hemp seeds and as a building material to make blocks called “hempcrete.”

Hempcrete is made by combining the hemp fibers and lime in a mold. Ako said hempcrete is termite-resistant and provides better ventilation than various other building materials.

Ako, a retired University of Hawaii biochemist, said as part of the project, those involved in the hemp project in Waimanalo plan to make samples of hempcrete.

Three varieties of hemp were planted on less than a quarter acre of land in Waimanalo: subtropical hemp, which grew to almost 10 feet in 15 weeks; seed hemp that topped out at 3 to 4 feet, with half of the plants bearing seeds; and a third crop from Italy that grew to 1 feet to 2 feet before flowering and dying.

Noting Hawaii already grows corn and soybean seed that’s sold worldwide, Ako said hemp could be an additional crop. “There’s a lot of interest,” he said.

Although hemp is part of the cannabis sativa plant species along with marijuana, it contains a small fraction of the amount of tetrahydrocannabinol, or THC, needed to get a user high. But in 1957 the U.S. Drug Enforcement Administration began interpreting the Controlled Substances Act to include prevention of industrial hemp growing.

The university project took shape when Hawaii’s Legislature passed Act 56 after the federal Farm Act in 2014 allowed industrial hemp to be grown as a state or university initiative.

The National Conference of State Legislatures said 13 states, including California, Oregon and Colorado, have statutes establishing commercial industrial hemp programs.

Thielen said researchers had had difficulty getting authorization from the DEA to get hemp seeds.

Thielen said she will be meeting with members of Congress, as well as the assistant secretary of agriculture in Washington, D.C., to talk about passing national legislation to accelerate the farming of industrial hemp.

The DEA in Honolulu was unavailable for comment.