Usually: Late August to early September
Zeltfestival Ruhr
Bochum
Over two weeks of concerts across the genres in and around the tents at the Kemnader See, on the border of Bochum and Witten.
Evenitto's guide · Live music in Germany
From Summerjam at the Fühlinger See in July to Juicy Beats in Dortmund, the Zeltfestival Ruhr at the Kemnader See and the Wave-Gotik-Treffen in Leipzig: the summer's music festivals, with dates as their organizers announce them.

The festivals people plan their summer around, with the time of year they usually take place. Dates change every year, so check the festival's own site.
Usually: Late August to early September
Bochum
Over two weeks of concerts across the genres in and around the tents at the Kemnader See, on the border of Bochum and Witten.
Usually: Late July
Dortmund
The summer festival in Dortmund's Westfalenpark, with several stages and dance floors over one or two days in July.
Usually: Early July
Köln
The big reggae festival at the Fühlinger See in Cologne, three days of music by the water.
Usually: Whitsun (May or June)
Leipzig
The gothic scene's big annual gathering: concerts, readings, theatre and parties at venues across the whole city, the Felsenkeller among them.
Mon 19:00 · Volksbühne am Rudolfplatz · Köln
€39.90

Tue 19:30 · Erholungshaus Leverkusen · Leverkusen
From €38.00

Wed 19:30 · Erholungshaus Leverkusen · Leverkusen
From €43.00

Wed 20:00 · Scala Club · Leverkusen
From €37.00

Thu 19:30 · Erholungshaus Leverkusen · Leverkusen
From €51.00

Thu 20:00 · Theater im Gründungshaus · Mönchengladbach
From €29.60

Fri 19:00 · Erholungshaus Leverkusen · Leverkusen
From €41.00

Fri 19:30 · Theater im Gründungshaus · Mönchengladbach
From €38.50