Graduates: Throw that cap high, but think twice about tossing the gown.

College students' leftovers might be composted and their dorms partly solar-powered, but most students will still accept their diplomas wearing petroleum-based polyester gowns that they will then throw away.

Now, often at the urging of their students, more colleges and universities are greening their graduation ceremonies.

One big switch: Gowns that quickly compost or that are made from plastic bottles, which can be recycled.

Minneapolis-based Jostens offers gowns made of acetate -- which comes from tree and plant fiber and will decompose in a landfill within a year. Next year, the University of St. Thomas might go with gowns that were once plastic bottles, said Tony Erickson, the university's bookstore manager.

But some colleges, along with the Sierra Club, have argued that it is better to stick with a traditional fabric -- and then reuse the gown. Less convenient, but better for the Earth.

Carleton College's gowns are 100 percent polyester. They are returned to the provider, Oak Hall, dry-cleaned with environmentally friendly chemicals and then reused.

"At this point, we feel that reuse of the gowns is as 'green' as recycling or composting," Carleton spokesman Eric Sieger said by e-mail.

Other schools donate their gowns to be worn again.

Beginning with the 2008 commencement, a few Macalester College students started a system for seniors to donate their gowns to Minnesota Internship Charter High School.

Volunteers -- wearing, in a nice touch, green gowns -- collect gowns at the reception following graduation and place drop-off boxes on campus so students can drop them off the following week.

Of course, green also goes beyond gowns.

As they sat on stage at Winona State University's commencement last week, the president and her party drank from aluminum -- rather than plastic -- water bottles.

Jenna Ross • 612-673-7168