Her yard might be weedy, but Meredeth Dash is trying to create beautiful underwater meadows in the James River.

Dash, a Hanover County homemaker, raises river grasses on her dining room table and plants them in the James.

A volunteer in the Chesapeake Bay Foundation’s “Grasses for the Masses” program, Dash started growing wild celery last year.

“People would come over to my house and be like, ‘What kind of science project do you have going?’ ” said Dash, 37.

Dash and other bay foundation volunteers planted their latest crop May 26 in the James at Westover Plantation in Charles City County.

Oysters, which filter pollution from water, get all the publicity — maybe because they taste better than grass. But aquatic plants such as wild celery, eelgrass and coontail are similarly important to the bay and its rivers.

The waving, green grasses absorb pollution, keep banks from eroding, add oxygen to water and provide shelter for fish and crabs. Ducks, geese and turtles eat the grasses.

The grasses also trap waterborne dirt. When Captain John Smith explored the bay region four centuries ago, scientists believe, he found waters that were much clearer than today’s, in part because grasses were so abundant.

The plants are called bay grasses, river grasses, and for jargon junkies, submerged aquatic vegetation, or SAV.

Grasses are key indicators of bay health, and right now the signs are not good. Scientists estimate that grasses grow on about 10 percent of the area they once covered.

Still, patches have returned in recent years to places such as the freshwater reaches of the Chickahominy River, said Ken Moore, an underwater grass expert with the Virginia Institute of Marine Science.

Grasses reflect the chicken-or-egg complexity of the bay. They improve water clarity but need clear water to thrive. That’s because cloudy water — darkened by algae and dirt — blocks sunlight the plants need.

Once covering an estimated 600,000 acres, underwater grasses grew on about 64,000 acres last year. Scientists with the Chesapeake Bay Program, the federally led cleanup effort, would like to see 185,000 acres in Virginia and Maryland waters.

As the bay cleanup progresses, Moore said, the waters should get clean enough in a few years to nourish a resurgence of grasses.

“It’s going to occur as a big leap. In some areas, it might be helped by having some founder beds out there.”

Those “founder beds” would provide seeds to produce even more grasses. That’s where the Chesapeake Bay Foundation, an environmental group, comes in.

Since the late 1990s, the group has enrolled about 2,000 volunteers such as Dash to grow tens of thousands of aquatic plants and put them in the James and other waters.

The effort is not creating vast new beds, but it probably “helps incrementally,” said bay foundation spokesman Chuck Epes. At the same time, the program helps people develop a conservation ethic.

“We hear all the time, ‘What can one person do?’ ” Epes said. “Here is something one person can do and make a difference.”

It takes about three months to grow grasses at home.

Dash lives in the Atlee area with husband Randy, also 37, a work-at-home computer programmer, and sons Simon, 6, and Drake, 3.

In the family’s dining room recently, Simon and Drake poured a few jars of water into a black tub holding two trays of feathery grasses about 4 inches long.

Simon and his mother used their fingers to dislodge tiny clumps of algae from the fragile sprouts.

“It’s like hair,” Dash said, “so you just gently and slowly work your hand through it.”

The children love watching the grasses grow, Dash said. “It’s connecting kids back to nature, which is so important right now.”

Dash said she has long worked to help the environment. Among other efforts, she and Randy don’t fertilize or put pesticides on their yard because rains can wash the chemicals into streams.

“You would know our lawn because it’s full of what I think are beautiful weeds,” she said.

Volunteers in the “Grasses for the Masses” program pay $40. In return, they get seeds, instructions and (on loan) a simple grass-growing setup. The volunteers provide sand, soil and a little maintenance.

Once the setup is running, with lights and a pump, you just add water occasionally and brush off algae.

“All you do is plant the grasses and let them grow,” Dash said.

Maybe someday soon, grasses will thrive like that again in the wild.