As of today, House of Blues (which also promotes Blossom events) has stopped selling tickets via Ticketmaster, and now sells online exclusively via livenation.com.
HOB's website redirects to Live Nation’s.
Tickets are also available via Live Nation's toll-free phone line (877.598.8703) and House of Blues' box office (216.523.2583), which offers lower fees than the online sites. —D.X. Ferris