Theresa Carter was upbeat and hopeful on Dec. 26 when she and a small group of supporters, with a group of media trailing behind, arrived at Target Corp.’s downtown Minneapolis headquarters with a petition asking it to stop using plastic bags at stores.

Now she’s wondering why the retailer isn’t complying with a Minneapolis ordinance that took effect on Jan. 1, requiring all businesses to charge customers 5 cents for plastic or paper bags.

“Certainly Target knows how to have a 5-cent line item in the checkout lane,” said Carter, a self-described Target shopper who launched an online petition at Change.org that has drawn more than 480,000 signatures. “It’s the opposite of leadership on this.”

The city of Minneapolis said it has sent an advisory notice to Target and Whole Foods after receiving complaints through its 311 line. Linda Roberts, the city’s assistant manager of business licensing, said the aim of the letter is to educate, not penalize. Businesses have a six-month grace period before officials will give warnings and levy fines.

“The spirit of the code is to change the behavior of the consumer,” Roberts said. “We want the consumer to be bringing their own bag. Making that behavioral change is going to take some time for us all.”

She added, “It’s also going to take time for our retailers to develop training and to update point-of-sale systems and implement this.”

Target said in a statement that it plans to implement the fee beginning Feb. 1.

Whole Foods has not offered plastic bags at checkout since 2008. The company said it will begin charging customers on Monday.

“We’ve seen that guests can be frustrated by the change and appreciate having some time to get educated on the need to bring their own bag,” Target said in a statement.

“Because our guests’ satisfaction with the overall shopping experience is our top priority, we’ve been taking time in Minneapolis to educate our shoppers on the new ordinance.”

Executives point to efforts Target is taking to reduce plastic use, particularly with packaging in its supply chain. Target’s plastic bags are made with 40% recycled content, and recycling kiosks at stores keep unwanted bags and other items out of landfills. Target offers a 5-cent discount for shoppers who use their own bags.

Minneapolis is one of a growing number of cities and states to take action to try to curb use of plastic. Supporters hope the new rules will reduce litter and persuade customers to use reusable bags. Retailers keep the money collected.

In April, Duluth retailers will begin collecting a fee of at least 5 cents for most plastic bags used to carry food or merchandise.

At least eight states — California, Connecticut, Delaware, Hawaii, Maine, New York, Oregon and Vermont — have placed an outright ban on single-use plastic bags, according to the National Conference of State Legislators. Americans generate more than 4 million tons of plastic bags, sacks and wraps each year, according to the U.S. Environmental Protection Agency. About 13% is recycled.

Minneapolis retailers such as Cub, Lunds & Byerlys, CVS, Walgreens, Kmart and Holiday Stationstores have started charging for plastic. Best Buy doesn’t have any stores in the city of Minneapolis.