Marian Garden

One of my "wants" is to have a nice flower garden planted in the rock bed just outside the side entrance of my home. I've been looking through some plans, and I like this one. I want it to be a Marian Garden and I've looked into that. I'm hoping this Fall to be able to get out and get it started. I'm not very educated in gardening, although I love the thought of it. I wonder if I can plant flowers in the Fall? I suppose certain types can and certain ones can't be planted that late in the year. Research!!