Does moss grow pretty rapidly?

Question:I just bought (6) small potted 'sheets' of it for under a huge ugly bush in the backyard. It was trimmed somewhat underneath so has partial sun--to strong lit sun area's this particuliar moss grows in FS>but was wondering if it REALLY WILL SPREAD FAST?!
Good soil here, and good drainage
bought from spring nursery
says to space them out like 10 in.
in ur exp. does it grow rapidly? And how far out does it 'spread' around?
thx

Answers:
Not a real fast grower. Moss likes acid. Try using Mir-acid made by Miracle Gro.