Griffiths, 19, said: "All I knew about Gretna before I came here was that it's where people get married. But I now know they have an SPL side too.
"While I'm here I want to prove I can play at this level. Loan moves can kick-start a player's career and hopefully that will happen for me.
"My chances at Blackburn were limited but I'm sure they'll send someone to watch me while I'm here and it's up to me to impress.
"But first and foremost I want to keep Gretna up."