In Luoyang is there peony festival in April? When it starts and where?

Based on the lastest information, the festival wil be held from April 5 to May 5, 2017. You can make your travel plan according to this.
You can appreciate the peony blossom at the following places:
Shenzhou Peony Garden
Address: the opposite of White Horse Temple
Xiyuan Park:
Address: 250 yards northeastwards of the intersection of West Jiudu Road and Nanchang Road.
Have a nice trip!