The reason why the EC chose to conduct the poll in three phases, sources said, was that Anantnag was a serious security challenge. Anantnag will go to polls in Phase 3 on April 23, Kulgam in Phase 4 on April 29 and the “terror hotbeds” of Pulwama and Shopian in Phase 5 on May 6.

from Times of India https://timesofindia.indiatimes.com/india/3-part-anantnag-poll-due-to-serious-security-risk/articleshow/68366101.cms