Edmonton is asking citizens to take 15 minutes this week to pick up litter.

The 15-to-Clean Challenge launched its 2011 Capital City Clean Up Tuesday.

The city is hoping to out do last year's campaign, the most successful in its five-year history.

Nearly 1,000 block captains, 170 schools and 18 litter and anti-graffiti initiatives helped reduce litter by almost a third, earning Edmonton the 2010 national Communities in Bloom award for tidiness, said the city.

The clean-up campaign involves numerous city departments including transportation, parks and waste management.