My grandfather used to put the seeds in damp spagnum moss. Place paper towel on table. Put dampened moss and seeds on paper towel. Roll up paper towel and place in snack bag. Close bag and place in fridge. We would start checking on them in about a month, and would check about every 10 days thereafter until the seed had sprouted.
I don't remember ever doing black rose seeds but there all different colors and types of roses. He was a hybridizer and held several rose patents. I hope this helps you.