The traditional Derletalfest is the biggest open-air spectacle in the borough. It has been taking place since 1985 and is organized annually by the district administration office. Since 2018, it has also included the "Rock im Tal" music festival (see "Forms and links").

The Derletalfest offers a good opportunity to get information about the work of the associations and Hardtberg's diverse club life at numerous stands.

Clubs and organizations from the district that would like to participate in the Derletalfest are welcome to contact the Hardtberg district administration office.

The next Derletalfest with "Rock im Tal" will take place on Saturday, June 21, 2025.