This event has a website https://www.kirschbluete-bonn.de/, where you can monitor the current situation and determine when to go. The same information is available in the official instagram https://www.instagram.com/kirschbluetebonn/. Usually it is the middle of April - the end of April, our photos were taken on April 20. But in case of an early spring, blossom can start even in March. Note that the best blossom lasts only 3-4 days, so you have to check the information every day.
Blossom can found on the streets of Heerstraße (N 50 44.439 E 7 05.648) and Breitestraße (N 50 44.401 E 7 05.803). Considering that it lasts no more than 10 days, the place is quite popular with a lot of tourists.
Photos without tourists can only be taken early in the morning.
Getting there: The nearest tram stops are Bonn, Stadthaus or Bonn, Rosental. From Bonn Hbf Central Station is about 1 km on foot.