With ever-smaller yard sizes, high gas prices and fears of global warming, Americans are ready for earth-friendly push mowers, right?

Dream on. Sales of lawn tractors are growing healthily, along with the size and power of the machines themselves.

Most noticeably this spring, the venerable John Deere Co. has begun selling its prestigious tractors at the Home Depot, breaking with its longstanding practice of retailing exclusively through a dealer network.

The deal has been accompanied by a full-bore TV advertising campaign by both companies in commercials that play up the cachet of the brand, with its distinctive green and yellow livery and reputation as the hallmark of American agricultural technology.

But the agricultural connection, once a selling point for suburban lawn tractors, has been supplanted by a different metaphor: the modern automobile, particularly the indulgent Sport Utility Vehicle.

Sleek and muscular bodywork, padded seats and steering wheels, cup holders, cruise control, automatic transmission, all are pretty standard fare for machines that once were so ugly they had to be veiled to company. This spring, the Home Depot has set up special display areas in 1,200 of its 1,550 stores where customers will find two of the John Deere models equipped with a 12-volt power port to plug in a cell phone or CD player, conceivably even a laptop.

As with SUVs, the other marketing pull is pure horsepower. Top-of-the-line lawn tractors now exceed 20 horsepower, and the largest machines — called garden tractors and designed for attachments such as snowplows and rototillers in addition to mowing — have enough power to send whole stables out to pasture. John Deere’s G100 model has a 25 horsepower gas engine. The biggest model at Sears is propelled by a 27 horsepower motor. By comparison, early versions of the four-seater VW Beetle buzzed along with a 36 hp engine.

Do you need such might to scythe your grass?

“When I was a kid, we had lawn mowers that were 3 1/2 horsepower,” said Bob Mackey, Sears’ buyer for tractors and lawn mowers. “It cut my grass.” Today, the mentality is “the more power, the better.”

John Coffman, the product manager for tractors for Sears’ Craftsman tools and equipment, said there is another force at work: Horsepower envy. “We hear: ‘The neighbor has a 15 (horsepower), I want a 16.’ “

This might be understandable if the domestic greensward were getting bigger, but the once-generous suburban and exurban spread is shrinking as land values soar. Nationwide, the median size of the single family home lot is now a modest 9,000 square feet — less than a quarter acre. In the 1970s, it was closer to a third of an acre, said Gopal Ahluwalia, vice president for research at the National Association of Home Builders.