A raised bed without any solid bottom is just the same as planting in the ground. So you need regular garden soil, aka topsoil, amended with compost or composted manure to your degree of preference.

And it is always a good idea to integrate the soil underlying the raised bed with what is used to fill it to avoid interface issues. Doesn't need much - just a loosening or a thorough scraping of the existing ground soil.

Ann, my rose have been growing in 11inch beds. I’m going from fence boards to landscape timbers, so just a two inch drop. I’m in zone 9b, around Houston. This is my 3rd year with my roses. My first year get we’re all in the ground in the hard clay and I never amended the soil so they all suffered. Last year I put them in the raised boxes and they have been much happier, but the boxes are only 2ft wide, onviously they need some more room. They do have access to the soil underneath the bed. :)

I probably shouldn't have commented, because I'm not much of a rose grower. I thought they'd like a much deeper root zone.

Ann,

The roots do go deeper, if the box was closed at the bottom they would definitly need at least 2ft of box height. raising them is just to help with drainage. My native soil doesnt drain lol. so 50/50 top soil and compost in stead of sand?

You don't need that much compost. More than 25% organic matter is considered excessive. And it will shrink down a lot as well. You can always mulch with more compost once the roses get established.

Okay thank you