Blair Blanchette was halfway through her demonstration on growing underwater grasses indoors when she stopped midsentence, assessing her audience.

“I’m getting faces from everyone that say, ‘This isn’t gonna work,’” said Blanchette, the Virginia grass-roots coordinator for the Chesapeake Bay Foundation. “But we’ve had 2,500 participants in this program, and they’ve all grown grasses.”

She didn’t dwell on the fact that most of those participants over the program’s 17-year history have been school-age children who are used to such science projects — not diplomats representing their countries at embassies in Washington, DC. But, an organizer from the U.S. State Department was quick to point out, there will be prizes for the embassies that grow the tallest and densest grasses come June.

The U.S. State Department’s Office of Foreign Missions thought the diplomats from 14 countries, such as Costa Rica, Iraq, Malta, Pakistan and Somalia, might benefit from a five-month lesson in submerged aquatic vegetation that — as a bonus — would benefit the Chesapeake Bay. Their crash course in grass-growing, which took place in a restored chapel on the former Walter Reed Hospital campus in Bethesda, MD, is part of the department’s Greening Diplomacy Initiative, a program in its third year aimed at engaging other countries in environmental issues.

Last year, the program deployed diplomats in a half-dozen U.S. cities to remove more than two tons of trash during a one-day shoreline cleanup, said Cliff Seagroves, acting deputy director of OFM at the time. The year before that, diplomats helped plant 40 trees on a government campus in DC.

This year, the agency wanted to do something specific to the Washington area environment where many of these embassy staffers will spend a few years before returning to their countries. The foundation’s Grasses for the Masses program emerged as the best option, despite the group’s lack of underwater-growing experience.

“We’ve never grown (underwater) grasses at the State Department, and we doubt you have, but we look forward to a bountiful crop,” said Seagroves, who took four grass-growing kits back to his agency’s office.

In case sheer optimism wasn’t enough inspiration, Seagroves also mentioned the prizes his office would be awarding to embassies: one for the tallest and one for the densest batch of grasses come June 5. That’s when the diplomats will roll up their pant legs to permanently plant the fruit of their labor into the Potomac River at Mason Neck State Park in Lorton, VA.

“This is what your grasses could look like then,” Blanchette said as an underwater photo of green, swaying strands filled the PowerPoint screen.

More than a friendly competition between embassies, Blanchette explained how growing the footprint of grass beds in the Bay is also ecologically important work. These beds of submerged aquatic vegetation serve as “coastal canaries of the ecosystem,” she said, requiring relatively clean water to thrive while doing their part to filter out pollutants and provide habitat for various species wherever they are present.

Decades of pollution have caused algae blooms and sediment buildup that can block the sunlight that grass species like wild celery (Vallisneria americana) — which this group would grow — need to survive. Surveys estimate grass beds in the Bay are at 50 percent of their historic levels, Blanchette said.

Bay grasses have been coming back of late, and covered more than 92,000 acres in 2015, the most recent year for which data are available. But the Baywide goal is to get back to 185,000 acres by 2025 — and every seedling counts.

The Bay Foundation may be a regional nonprofit focused on the Chesapeake, Blanchette told the group of diplomats, “but these are global problems that are relevant to you. No matter where you are from, seagrasses probably grow there.”

“Except in Switzerland,” a diplomat from the landlocked country noted with a grin.

After learning why these water-filtering, shoreline-protecting, oxygen-infusing plants are important to local ecosystems, the diplomats wanted to know — in no shortage of detail — how to get them growing in their offices.

They left after the one-hour lesson that day with a black plastic basin filled with all of the supplies they’d need, including a water pump, a heat lamp, sand, compost and a small bag of seeds. The kit was so bulky it took two people to carry.

Blanchette suggested the novice growers find a sturdy table space where their plants could grow for the next five months at a stable room temperature, with an electrical outlet and a window nearby, if possible.

Then the troubleshooting questions began: What if the embassy turns off the power — and the heat — each evening after workers go home? What if there is no window? What if your office is so cold that water in a cup once froze on your desk overnight?

“Do what you can to experiment, and try to keep the water temperature around 78 degrees,” Blanchette said in response. “Maybe you buy a moving blanket to put around the bin or cover it in Saran wrap. We suggest you run the heat lamps 24 hours at the beginning until your seeds sprout.”

Once the grasses have gotten a good start, caretakers need to do little more than maintain the water level, clean out any algae that builds up and rinse the filter, Blanchette said. They can use tap water for refills, she told them, but only if that water sits out for a day beforehand to allow chlorine to evaporate before it is added to the bin.

Anggarini “Ririn” Sesotyoningtyas, a third secretary of economic affairs with the Embassy of Indonesia, said she was optimistic about her team’s growing prospects as she picked up her kit after the demonstration.

“We have so much emphasis on maintaining biodiversity, especially in the water, because we are an island country,” she said. “This is a nice example that we can replicate in our home country, too.”

The Indonesian embassy had reserved only one grow kit before the demonstration — and before they found out other countries had purchased more than one to increase their odds of success. Sesotyoningtyas later emailed that she was working to get a total of four bins — the maximum — so she could display a pair of them at both the embassy and ambassador’s residence buildings.

It would also increase her odds of beating China. A pair of secretaries from that embassy carried out four bins after the demonstration, during which they’d taken copious notes.

“We hope to win,” first secretary Ning Wei said.