They are logged out in the Mirror Orchard/Lake House where Morgaine the Sly spawns in Elwynn Forrest. (http://www.wowhead.com/npc=99)
You can message/in-game mail this toon, or either of the "Mogs" in the Star Onion Brigade (Mogknight/Mogtaru) and I'd be happy to help you out with setting up a meeting with them.
For this achievement you do need to have the Spring Flowers item, but it can be completed outside of the holiday time. So if you saved them from last year you can do this before the holiday starts.