When the £500-million Cabot Circus opens next month Bristol's retail heart will be dramatically transformed.

With its department stores, 120 new shops, apartments, bars, restaurants and a 13-screen cinema, the development will focus attention back onto the city centre, delivering a huge boost to the existing Broadmead area.

Broadmead is already undergoing an £11m revamp with new paving, lighting, street furniture and signs, landscaping, upgraded store elevations and six new shops in a project partly funded by the traders themselves.

Now businesses are being asked to put their hands in their pockets again – this time to fund a five-year marketing campaign and regular cleaning regime to ensure Broadmead retains its appeal.

If traders in Broadmead agree to fund the project, cash will spent on developing a full calendar of events, street entertainment and various other promotions.

Cleaning and maintenance would be improved to include hourly sweeping patrols, removal of graffiti and chewing gum and prompt and efficient trade waste disposal.

Businesses say that although work to give Broadmead a facelift has been disruptive and taken too long, they believe that when the improvements are completed, customers will be flocking to their shops. And they have welcomed the idea of investing further cash and helping Broadmead thrive alongside Cabot Circus.

Paul Davis, owner-manager of Parsons Jewellers in The Mall Bristol (formerly the Galleries), said: "The groundwork has been done with the upgrade of the street environment, but we need to protect our investment, ensuring the standards of cleaning are maintained and are up to the high levels that will be set by Cabot Circus."

The funding for environmental improvements to Broadmead, which has 300 stores, came about through a Business Improvement District (BID) strategy arranged three years ago by the Broadmead management team.

A BID is a precisely defined area of a commercial district where business ratepayers vote to fund improvements over and above those funded by local councils.

Of the £11m raised through the first BID, £1m was raised from a levy on the retailers themselves, the remainder came from Cabot Circus developers The Bristol Alliance, The Mall Bristol, Bristol City Council, the South West of England Regional Development Agency and other property owners. If retailers vote for the second BID in October there will be a another pool of funding available for marketing initiatives.

Broadmead manager John Hirst said: "After the huge success of BID1 the challenge now is to ensure that the existing Broadmead stores benefit from this once-in-a-lifetime world-class opportunity."