How green is your yard?

On a rainy day this spring, a crowd of summer-starved nature lovers showed up at a Scituate garden center to hear an author talk about his new title, and 30 inspired souls bought the book. The draw? Paul Tukey's "The Organic Lawn Care Manual," which argues that homeowners' yards should be as friendly to the environment as they are to the people who enjoy them.

It was a telling start to a summer in which many suburbanites are rethinking what it means to have a good green lawn.

Across the region, garden centers report they are receiving more requests for environmentally sensitive plants and products, as residents worried about the effect of pesticides and herbicides on children, pets, and the environment seek alternative ways to make their yard attractive.

There has been a big jump in sales of organic lawn products, said Chris Kennedy, owner of Kennedy Country Gardens in Scituate. "People are much more conscious of the safety of the environment and ramifications of what they do," he said.

"My sales are three and four times what they used to be" for tall fescue grass seed, said Patrick Greggo, owner of the First Parish Nursery Centre, also in Scituate. Fescue grass is more drought-resistant and requires less watering than the non native grasses that traditionally cover New England lawns.

Customers are bringing Greenscapes guides with circles drawn around recommended plants into her store, said Claudia Lambert, the garden store manager for the family-owned A.J. Tomasi Nursery in Pembroke. It shows that a new wave of gardeners not already committed to organic gardening is embracing a "green" approach to landscaping and lawn care, she said.

"It means they are getting started," Lambert said. "They have started to educate themselves."

The new way of thinking advocates growing native, drought-resistant plants as alternatives to traditional lawns, using organic lawn care products, and reducing the amount of water lavished on thirsty lawns.

Those are the principles of the Greenscapes program, funded by state and federal grants, which holds workshops on topics such as lawn alternatives, low water maintenance, rain gardens, and composting and recycling. It also offers discounts on "green goods" such as sprinkler timers, drought - tolerant plants, and organic fertilizers, and runs a Greenscapes lawn contest.

More than 70,000 homes in the area south of Boston now receive the information guide published by Greenscapes. The mailing list expanded by 10,000 new homes this season.

The program drew 60 and 100 attendees to its first two workshops this year, said Julie Uhler, manager for the program sponsored by the North and South RiversWatershed Association. Most of the participants said they planned to put at least some of the ideas they heard about into practice, and more than 90 percent signed up to receive future materials.

That is a notable departure from decades of a different sort of yard practice.

A chemical lawn-care regimen has three parts: a nitrogen-rich fertilizer, an herbicide to kill weeds, and a pesticide to control grubs that feed on grass roots. For about $59, a homeowner with a 5,000-square-foot lawn can buy all the products needed for a year, apply them in four easy-to-follow steps, and end up with a pleasingly green lawn. The attraction, even organic devotees concede, is its simplicity.

But some of the components have drawn increasing scrutiny over the last decade or so.

Bifenthrin, the key ingredient in many grub- and insect-control products, for example, has been listed by the US Environmental Protection Agency as a possible carcinogen. Its use also has been banned in several counties in southern New York state. A common herbicide, pendimethalin, is also listed as a possible carcinogen.

Some studies link another weed killer -- 2,4 dicholorophenoxy acetic acid, or 2,4D -- to increased cancer risk, but the EPA has not classified it as a carcinogen.

Advocates of purely organic practices say that, with patience, a homeowner can create a beautiful lawn and garden without chemicals.

For weed control, the organic programs use two yearly applications of corn gluten, which forms a barrier around weed seeds and prevents them from putting down roots.

For fertilizer, an organic waste product such as poultry manure is used.

To control grubs, organic lawn-care backers use milky spore, a fungal disease that attacks grubs naturally. The green approach also relies less on heavy watering.

Towns have jumped on the green bandwagon, in part because high water use in dry summer months stresses municipal water systems.

According to the Greenscapes program, watering a one-acre lawn with the inch of water automated sprinkler systems are set to deliver uses 26,000 gallons of water. It's no surprise that towns such as Scituate, Duxbury, and Marshfield average almost twice as much water use over the five-month summer watering period than for the five winter months.

Areas with what the state terms "stressed" basins, including the Weir River (in Hingham and Hull) and parts of Norwell, Weymouth, and Pembroke, are required to impose restrictions to limit summer water consumption. Summer watering restrictions have become common.

State and local officials also attribute poor water quality in some regional waterways to stormwater that includes chemical pesticides and fertilizers. The city of Quincy has recently spent millions in an effort to keep stormwater out of its coastal waters and improve water quality at Wollaston Beach.

Environmentalists say green lawn care practices are also better for the surrounding ecosystem, resulting in less stormwater runoff and pollution of nearby waterways and wetlands.

Green lawn care advocates say their methods have a personal payoff, too. Marshfield nurse Virginia Elsenhans, the winner of last year's Greenscapes program garden contest, said spending time close to the earth outdoors "is essential to health."

Lambert agreed. Noting that plants use carbon dioxide and give off oxygen, she said people and plants have "symbiotic" relationships. "We need them."

Robert Knox can be contacted at rc.knox@gmail.com. Ralph Ranalli of the Globe staff contributed to this report. For more information on Greenscapes, go to greenscapes.org.