How does everyone brumate theyr garters ?

Last year I brumated my marcianus after a month of not eating in december until he started getting active again in May. I had him in a quiet,dark and unheated room that was always around 8-10 degrees in a small box with wet oak leaves and a water dish. I opened the box every week to change the water, soak the leaves and check the snake.

I think it went well but If you think I was doing anything wrong please let me know before I brumate him this year