Wal-Mart, Home Depot Go Green

Rothbort said that if he were an investor in these companies, he would be concerned that "they're spending more of my money to sell the same product."

Craig Johnson, president of Customer Growth Partners, said consumers are more aware of environmentally friendly products now than they have been in the past, so it is a good time to try and sell them. But he also said the two companies can benefit in other ways by going green.

"Both companies have had challenging public relations problems," he said, referring to the departure of controversial former Home Depot CEO Robert Nardelli and Wal-Mart's labor issues and lawsuits connected to the firing of a former marketing executive.

"Frankly, Wal-Mart has been outpaced in many ways by Target(TGT) and Costco(COST)," he said. "One of the classic PR strategies is to be seen as a good citizen in other areas."

Johnson said the move toward green products is of marginal importance to the investor.

"It's not going to change a $50 stock to a $75 stock," he said. "From an investor point of view, it's a positive, but it won't make or break them."

Shares of Home Depot were trading up 78 cents, or 2%, to $39.34, while Wal-Mart was slipping 11 cents to $47.96 recently.

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