It was easier during the Middle Ages when only medals of St. Joseph were "buried" to seek his saintly intercession.
How it came to pass that using his statue instead is "more effective" seems vague to Church historians! And "burying" it upside down led to the invevitable joke that St. Joseph eventually lost his hair as a result thereof!

At any rate, whether it is supertitious or not, some people avow getting help from St. Joseph in selling their house!
(I think it becomes more efficacious if one recites the Novena to St. Joseph!)
Good luck!