It's like gardening, William Wilcox and Paul Bagnall explain, but with a twist. All the planting is done underwater.

Anxious to see eelgrass beds thrive in Vineyard waters again, staff members from the Martha's Vineyard Commission and town shellfish constables including Mr. Bagnall have gone to great lengths over the last five years to kickstart the restoration. From laying sod to sprinkling seeds, they are determined to help replenish eelgrass beds once prevalent in ponds such as Sengekontacket.

But it's a small price to pay, they agree.

"The reason you concentrate on eelgrass is that it's the keystone. If you can bring eelgrass back, all sorts of habitat can flourish here," said Mr. Bagnall.

Eelgrass, which looks like thick stalks of brownish-green grass, grows on the shallow bottoms of brackish or salty ponds and bays. Some creatures eat it; others hide in it. Bay scallops, the crown jewels of Vineyard shellfishing, cling to eelgrass blades as larvae and nestle in eelgrass beds as adults.

This plant has largely been depleted in North Atlantic waters from Nova Scotia to North Carolina. Several areas of the Vineyard are no exception, and officials and fishermen alike want it back. They are willing to experiment with Mother Nature to help the revitalization along.

Last Thursday, Mr. Wilcox and his summer assistant Tonya Jillek - with the help of Oak Bluffs shellfish constable David Grunden and Mr. Bagnall - began rolling out the third eelgrass gardening technique they have tested since 1999.

"With any luck, 10 per cent will stick, and it will be worth the effort," said Mr. Wilcox.

Four areas of Sengekontacket Pond, two in Oak Bluffs and two in Edgartown, were the testing grounds this year. Less than 20 years ago, eelgrass beds around Sarson's Island in Sengekontacket were so thick, a motorboat couldn't navigate the area, Mr. Wilcox said. Throughout the pond, except for some patches in Major's Cove, eelgrass beds have all but vanished. The last wave of depletion came in the early 1990s, when Mr. Wilcox suspects a background presence of the wasting disease reactivated. The wasting disease is blamed for wiping out much of the stock throughout the North Atlantic in the 1930s.

Friends of Sengekontacket, a nonprofit group dedicated to the health of this pond, is fronting the necessary $3,100 for the initiative. "This is short money if we can come up with a technique that works," said Mr. Wilcox. Much of the funding this year is needed to cover labor costs associated with Ms. Jillek's harvesting work.

Wednesday afternoon on the southeast shore of Sengekontacket, Mr. Wilcox and Ms. Jillek filled mesh bags with tall stalks of eelgrass while Mr. Bagnall fetched the shellfish department boat. The plants, with flowers newly budding on the blades, were harvested from Trapp's Pond just last week after water temperatures rose enough to trigger seed production. The holes in the mesh bags are just large enough to let the seeds slip through, small enough to prevent other creatures from sneaking inside to feed. These bags will drift with the currents in the pond, dangling from 40-foot lines affixed to buoys. As the waves buffet the bags, Mr. Wilcox hopes the nearly 40,000 seeds will fall away, germinating the pond's floor.

"This method is simple. You put it out there, then you forget about it and let nature take its course," said Mr. Wilcox.

This year's approach is more of a gamble, but the stakes are lower. They've invested much less money and manpower in the approach. They're counting on a 10 per cent survival rate, however, which could translate into a few thousand eelgrass plants in Sengekontacket next season.

Mr. Wilcox's biggest challenge is the spider crab - a foe he and Mr. Bagnall encountered in 1999 after spending weeks planting 40 to 50 eelgrass shoots and stabilized each shoot with a twig of bamboo.

"The crabs seemed to have a party with that. Even after we put up fences, they had a field day," said Mr. Wilcox.

How will they keep the spider crabs from feeding off the plants that will likely grow from these seeds?

"Hopefully just because of the sheer number we're putting out in four separate locations, the crabs will not be able to devour it," Mr. Wilcox said.

Eelgrass restoration efforts began on the Island in 1998 when officials mapped the eelgrass beds in Lake Tashmoo. They studied the health of the beds, paying particular attention to the presence of algae coating the blades. The deterioration of eelgrass health is thought to be an early warning sign of larger health problems for a pond.

The next year, in Sengekontacket and Farm Ponds, officials embarked on their first planting exercise - another effort apparently undermined by spider crabs. In 2000, officials tried a sodding technique in Edgartown Great Pond, where eelgrass beds had all but disappeared. About half survived. Algae badly fouled the survivors, however, an infestation they will not likely overcome.

"What works with eelgrass is just starting to be known. Mapping we've done over the years tells us that it comes and goes. That's why projects like this are worthwhile. If it works, it works in a big way. If not, we learn from our mistakes," said Mr. Bagnall.