Tony - MMeOw has made an excellent guide about Hedge Maze as a part of the Lotro Spring Festival. There are 5 different quest givers, all of which want you to do something different within the maze and one of the possible prizes you can get is the fish slap emote, /fishslap.
Also you can decorate your garden with a new garden dwarf or hobbit statue (screenshots made by zick).
Visit our Hedge Maze Gallery and enjoy!